According to the combining ability,heterosis,pedigree relations and morphological,physiological and genetic characteristics,as well as the practice of breeding,the maize germplasm of China were divided into five heterosis groups and nine sub groups,i.e.improved Reid,Lancaster (Mo17 and Zi 330 sub groups),Sipingtou,Ludahonggu and others (subgroups such as:germplasms from foreign hybrids;selected germplasms,Suwan germplasm and other low latitude germplasm).The limited availability of germplasm,the division and utilization of heterosis groups,and the improvement of germplasm were discussed.

The town of Nanshao, Changping county in Beijing has 264 hectares of land. One hundred and six soil samples were collected and analyzed for soil organic matte,total N,available N,available P and available K in 1993. The spatial variation of these soil properties was quantitatively analyzed by geostatistical methods. The contour of these soil characteristics was also drawn by Kriging method. The geostatistical method showed some importance in studying and estimating the spatial variation and changes of soil nutrient sona large scale.

The results of five-year test of no-tillage with maize straw mulching suggested that soil moisture content increase by 5.56% to 17.0% in treatment of NTMS(no-tillage with maize straw) compared with other treatments,soil bulk density decrease(0-10 cm soil layer) by 9.35% to 10.9% compared with other treatments,soil total porosity(10-20 cm soil layer)increase by 13.80% compared with NTN(no-till without straw mulching),soil water stable aggregate(≥0.25 mm,0-10 cm soil layer) increase by 104.5% compared with TN(tillage with no straw return).Also the results suggested that soil total nitrogen content in treatment of NTMS increase by 10.6% to 15.8% compared with other treatments,soil alkali-hydrolyzadle nitrogen content increase by 23.3% compared with TN(tillage with no straw return),and soil organic matter content increase by 29.0% to 33.8% compared with other treatments in 0-20 cm soil layer.Although the treatment of NTMS improved soil physicochemical properties,the significant higher yield of winter wheat corresponded with the improved soil was not found in the test.The further study on the question about how to increase winter wheat output in NTMS need to be carried out to exert its advantage sufficiently,then the soil sustainable use of land would be realized.

From 1988 to 1990, the ecological and physiological effects on root systems of wheat were studied under different soil water conditions. Results showed that the development of root systems could be inhibited by deficiency and oversupply of soil water. Drought might lead to the reduction of roots in the surface layer and the increase of the ratio of the roots in the deeper layer. When the relative soil water content was below 60%, the number of secondary roots of the individual plant decreased obviously. When it was below 50%,the root system reduced significantly.Less activity of root systems resulted from the higher severity soil water stress, and the least activity wax found in the flowering period. The wound sap flow of the single plant was in extremely significant positive correlation with the content of soil water. However, there existed an extremely significant negative correlation between the root-top ratio and the soil water content. It was found that the 40% relative soil water content was the lower limit index for severe drought in the later growing stage of wheat.

The genetic diversi ty of 23 maize inbred lines and one te osinte accession was analyzed based on microsatelli te (SSR) and AFLPs markers. With 40 pai rs of SSR primers, total ly 202 polymorphic f ragments were detected. Twelve AFLP primer combina tion (Pst/Mse ) were used, and total ly 444 polymorphic bands were produced. BothSSRs and AFLPs were highly polymorphic. The average of polymorphic informat ion content (PIC) was 0. 6 for SSRs. Percentage of polymorphic AFLP bands was 72%.The resul ts of cluster analysis showed that the acces sions asses sed could be clustered into five groups in both marker sys tems. This is partly in accordance wih the previous classi fication based on conventional methods but wi th some dif ference. It was suggested that both sys tem can be used to analyze the genet ic diver sity of maize inbred lines.

Based on national supervision base for aqu-i cinnamon soil fertility and fertilizer benefits in Changping,Beijing( 1991- 2004) , the effect of long-term fert ilization on crop yield and Soil organic matter. were invest igated. Themain results obtained are as follows: Compared with the check( CK, no fertilizer applicat ion) and single nitrogen fertilizer(N only) , combined applicat ion of N and P( NP) significantly increased both biomass and grain yield of winter wheat by400% and summer corn by 100% ; Compared with NP, treatment , N only, combined appplication of P and K( PK) , andcombined application of N and K( NK) , increased crop yield not significantly.The yield increament for winter wheat andsummer corn follows the following order: NPK+ pig manure( NPKM) or NPK + straw> NPK> NP. The content of soilorganic matter(OM) of NPKM treatment was higher than that of single chemical fertilizer treatment significant ly. In comparisonwith CK, soil OM with treatments of NPK+ Straw,NPKM, NPK, NP and N only increased by 7190% , 14156%,6151%, 5189% and 2156%, respectively. Therefore, balanced application of N, Pand K, and combined applicat ion ofNPK with Crop yield and organic materials play a very important role in improving soil OM status.

The object of this work was to evaluate the effects of conservation t illage and conventional tillage on soilmoisture dynamics, evapotranspiration ( ET) ,water use eff iciency (WUE) and winter wheat yield in long-term tillage exper-iment of North China plain.The tillage treatments included conventional tillage(CT) , conventional t illage with stubble incorporating(CTR) , rotary tillage with residue(RTR) , zero-tillage( ZT1) that direct drilled with standing stubble and zero-t illagewith residue( ZT2) .The results showed that no-tillage could increase soil moisture than conventional tillage in 0- 180 cmprof ile; and the moisture difference reduced as the soil layer increasing. Soil water storage showed with a wavy change in 0- 30 cm profile; and zero-tillage had a good effect on water storage. Soil water storage of 0- 180 cm profile was not signif-icance difference among the t illage treatments, but water storage of zero-tillage than that of conventional tillage; soil waterstorage with stubble incorporat ion was higher than that of without stubble incorpration. Evapotranspiration( ET) of ZT1 wasleast,which reduced water use 318, 3916, 5518 and 6118 mm respectively than CT, CTR, RTR, ZT2; however, the crop yieldand WUE of ZT1 was 5 13917 kg/ hm2 and 1319 kg/ (mm#hm2) , which compared conventional tillage( CT) respectively reduced29. 7% and 32. 4%.

Studies indicate that the disease is caused by a virus pathogen.The visions arc spherical shaped and enwrapped with double--layer capsule."I'he winter wheat plants with“dark-green dwarf" sy mptom and those stunted plants dou-ble-infected with GVheat Rosette Stunt Virus(WRSV) and MRDV are the ini-tial source of inoculum."I'he planthopper(Laodelphax Striatallus Fallen)is the vector of this visa:and the adul1 cf it:first er.eration is the main agent for distribution of this·irus causing dan;age to corn.The disease index caused by this virus varies greatly with the time of infection in respect to the grow-th stages of corn.1'he disease index is 55.0-67 for 9%seven leaves and a whorl,whorl stage and:y for eight Ica:and a whorl,id still copped to 2.8% for eleven or twelve leaves.The integrated program control is pried mainly on the rearrai:gctncnt of planting clai‘:and measures, such as WRSV disease prevention for demir:;shing-the source of inoculum,plan-ting tolerant cnlti、acs,eradication of[!isc sed >c,.dlinvs,favorable cultural practices and chemical control."I"he large de;;;on:tration area of.33ha has proved this integrated program to be effecti:e.The contrast is sharp.The per-ccntage of diseased plant is depressed from. 58.3% to 15.0% and the disease index from 29.6% to 4.4-5.3% cornparin; to the pre、ions culttmc nontreated. The comparison to the neighbouring fielc?:in the sane year non-treated shows that the percentage of diseased plant ana the disease index are depre>sed by 78.19%and 77.9% respecti、ely.

The chlorophyll content and corticoid content of Chinese Spring(CS)-Synthetic 6x substitutions and parents cultivars Chinese Spring (recipient) and Synthetic 6x ( cbnor) under the drought conditions and control treatments indifferent developing stages were measured. The results indicated that the chlorophyll content of SA,5B chromo substi-tution lines and the corticoid content of SB chromosome substitution line were significantly higher than Chinese Spring at0. OS or 0. 0l level from booting to grain filling stage under normal condition,while the chlorophyll content of 3A,4Dchromosome substitution lines and the corticoid content of 2A and 4D chromosome substitution lines were significantlyhigher than Chinese Spring at 0. OS or 0. 0l level under drought stress. It was concluded that the genes of controllingchlorophyll and corticoid content were probably located on SA,5B and SB chromosomes respectively under normal condi-tion,and that of controlling chlorophyll content and corticoid content were probably located on 3A,4D and 2A,4D chro-mosomes of Synthetic 6x respectively under drought stress.

With deep pots and non-weighting lysimeters,different soil moisture stresses are developed and maintained during turn green to maturing stage in winter wheat.The plant physiological and morphological status and development of root under different soil moistures are measured at all growth stages.It has been shown that the rational regulation of soil moisture can change obviously the ratio of root to shoot,suitable soil moisture stress (50%-60% of field capacity)promotes the development of root system and high soil moisture favors the growth of stem and leaf.The experiment results also show that leaf growth rate reduces when soil moisture content is lower than 60% of field capacity,which leads to total leaf area and solar radiation energy intercepted to decrease,and finally reduces the biological and economical yields in winter wheat.When soil moisture rises to 55% of field capacity from 46% of field capacity,photosynthetic rate increases slightly.However as soil moisture rises to 64% of field capacity from 55% of field capacity,photosynthetic rate increases greatly.If soil moisture is more than 64% field capacity of field capacity,photosynthetic rate almost remains stable.This indicates that photosynthetic rate has the threshold response to soil moisture and the threshold value is about 65% of field capacity.The transpiration rate for winter wheat increases with soil moisture.By considering the relationship among transpiration rate,photosynthetic rate and water use efficiency comprehensively,winter wheat has luxury transpiration to consume much more water under high soil moisture conditions.

Cell is the fundamental unit of living organism,proteins with different functions distributed in cellular compartments,including plasmolemma,nucleus,cytoplasm and organelles like mitochondria,chloroplast,Golgi,and endoplasmic reticulum etc.Protein subcellular localization is one of the key questions for functional genomics.The techniques used for subcellular localization of plants protein include fusion reporter gene localization,immunohistochemical localization,2D combined with mass spectrometry,marker enzyme-assisted localization and bioinformatics prediction.The development and application of high-throughtput protein subcellular localization technology stimulated the establishment of protein subcellular localization database.In model plant Arabidopsis thaliana,the number of proteins with localization data is over 4000.

Aiming to the status which grain yield of wheat wasn??t increase by increasing fertilizer and water quantity,a farmers fertilization inquiry coupled with soil and grain yield analysis was conducted to analyze the central factors influencing grain yield of wheat in Huimin county, Shandong province. The results showed that, the farmer applied about 424kg/ ha N, 226 kg/ ha P₂O₅ and 88 kg/ ha K₂O included organic fertilizer to wheat in invest igated sites, and the amount of N and P fertilizer applied was more than crop N and P uptake. Significant farmer-to-farmer differences in fertilizer ratewere found. Under farmers fert ilization and soil fertility condit ion, grain yield of wheat had close relation with soil organicmatter and spike number per acreage, weak relation with soil Olsen-P and seed number per spike and no relationwith soil exchanged K and weight per thousand seeds. Added increment of fertilizer didn??t increase grain yield of wheat with the farmers fertilization practice because of high N and P fertilizer applied and high soil exchanged K content.

The technique of SSR was introduced in detail through the test of four inbred lines using 137 primer pairs in maize.The results of the application showed that the SSR markers randomly distributed on the chromosomes. It could be used to study the genetic divergence of the inbred lines and the genetic dynamics of parents in pedigree efficiently.

The distribution and relationship of Olsen-P,CaCl₂-P,NaOH-P were studied in the profile of 0-100cM vegetable fields.The results showed that the content of Olsen-P,CaCl₂-P,NaOH-P was 123.8-399.6mg/kg,9.1-27.2mg/kg and 184.9-608.9mg/kg respectively in the profile of 0-20cM layer.The most of phosphorus in the soils was accumulated in the profile of 0-20cM layer and the content of Olsen-P,CaCl₂P,NaOH-P was decreased graduaily with the depth of soils.There was significant positive correlation between Olsen-P,CaCl₂-P and NaOH-P.The content of CaCl₂P was increased significantly when the content of Olsen-P was more than 55.6~63.0mg/kg.The content of Olsen-P was the "Change Point" of indicating the risk of phosphorus leaching.

A large number of soil fertility analysis and field trials were carried out in different regions of China.Results confirmed that soil nitrogen fertility in 20 tested soil types is low.The crop relative yield in N treatment is 69% in average,of which 65% accounts for"low nitrogen level",35% for"medium level",and none is"high"in nitrogen.Soil phosphorus fertility in these soils medium.The crop relative yield in-P treatment is 86.4% in average,of which 32% accounts for"high level"59% for"medium level",and 9% is"low"Soil potassium ferility in these soils is from medium to high.The crop relative yield in-K treatment 93.7% in average of which 41% accounts for"high level",56% for"medium level",and only 3% is"low".Soil fertility index for the 20 soil types have been worked out in accordance with soil test results and crop relative yields.

With the content of Cd2+ of 0, 5, 10, 20, 50 and 100 ppm, we grew wheat seedlings in knop nutritive solutions to study their effects on the growth and physiological functions of the wheat seedlings. And we found the effects. Under cadmium stress, both the growth of wheat seedlings and its roots were inhibited, and the inhibitions to the latter were more obvious| but 5 ppm-concentration cadmium could simulate the growth of wheat seedlings (Fig. 1 ).As the cadmium concentration increased, the proline and soluble protein contents in wheat seedlings also increased, and the proline contents would increase a lot with high cadmium concentration (Fig. 2 ). With high cadmium concentration, the electrolyte leakage increased obviously (Fig. 3 ), and this showed that cadmium could injure membrane. Cadmium could inhibite the activities of ?-amylase in endosperm, which intensified as the cadmium concentration increased, and which tended to abate as the wheat seedlings were growing (Fig. 3 ). Cadmium could induce the anode and cathode peroxidase isoenzyme bands of the roots new enzymatic bands,and also could intensify the activities of some original enzymatic bands (Fig. 4, Fig. 5). All these indicated that the effects of cadmium on the shape and physiological and biochemical functions of wheat seedlings has some relationship with cadmium concentration. Meanwhile, it showed that cadmium could do harm to the structure and functions of the cells in the wheat seedlings. The wheat seedlings had some adaptable protection to cadmium calamities.

Stress susceptibility index (1-Yd/Yp)/(1-∑Yd/∑Yp) used to determine drought resistance on the field is the alter form of drought resistance coefficient(Yd/Yp).The correlative coefficient above both is r=-1.Therefore，the former doesn't improve the defect of the latter.Using thirty winter wheat varieties as trial materials，after two years experim ents，the concept of drought resistance index in crops was put for ward，its expressing equation is:the yield in dryland x drought resistance coefficient/average yiell in dryland，it makes the drought resistance coefficient (physical index) correlate well with the yield in dryland (agronomy index) and is suited for breeder.

The flours quality characteristics of 28 winter，wheat variaties (31 wheat samples) were determined.Under laboratory conditions, the noodle making qualities of different variaties were evaluated by both instrumental and organoleptic methods, duality relationship between noodle and wheat was studied preliminarily, BreaKing strength of the dried noodles is posi-tively correlated with the protein content of flour and is strongly influenced by the gluten strength at the same time, The toughness of cooked noodles is positively correlated with the dough strength, and is influenced by the pro-tein content, The apperance quality of cooked noodles is negatively correlated with dough strength, bough weakness is found to be better indicator of the overall quality of cooked noodles.

Of 17 Chinese cabbage (Brassica campestris ssp. pekinensis) genotypes, 16 genotypes had produced microspore-derived embryos via isolated microspore culture. The production of microspore-derived embryos varied remarkably between these genotypes. The two genotypes with the highest embryo yield, T11 and CC11, produced 35928 and 34132 embryos per 100 flower buds, respectively. The growth environment (temperature) of donor plants obviously affected microspore embryogenesis. Average embryo yield of donor plants of CC11 grown in the greenhouse at 10℃/20℃ ( night/day) was 12 991.6 embryos per 100flower buds. But that of CC11 grown in the field at 10-15 ℃/0-40℃ (night/day)was 3,831.5, or 29.5% as high as the former.

Roots play an important role in water and nutrient uptake by crop. The investigation of root system development of winter wheat and the effect of nitrogen, phosphorus and soil moisture on its growth in the North Plain of China was made in 1990 and 1991. Roots were sampled by coring and the changes of root weight and length were determined in five development stages. The root weight growth rates were 0.845, 0.386, 1.921, 2.500 and 0.427g/m²· day and root length growth rates were 0.062, 0.0329, 0.310, 0.221km/m²· day in seedling, overwintering, jointing, heading and seed filling stages, respectively. The total root length and total root weight with time could be described by logistic growth function, and the exponential model was suggested for describing root system distribution with soil depth. N and P fertilizer application could promote the growth of winter wheat root system. Water stress reduced the root dry weight and root length, but root length and weight was greater in 0.3-1.20m depth under water stress than that of irrigated wheat. Irrigation could significantly increase roots in the stages of vegetative development and extend the root lifespan in the stages of reproductive development.

Water potential, ascorbic acid, proline, electrolyte leakage and wilting points in seedling leaves of 67 maize varieties were determined under drought conditions in the field and under water stress conditions in the laboratory,Results showed that these indexes were good for determining seedling drought resistance,The sensitivity sequence of these indexes to drought was ascorbic acid, electrolyte leakage, proline, and wilting points. The indexes determined in the laboratory can substitute those determined in the field.The Dormer could be used for variety drouhht resistance appraisal.

GA₁₊₄ and IAA contents of Wild-type and BT-type cytoplasmic male sterile lines of rice and their restores(Zhen 97A.B;Hua 76-49A,B)were detected with indirect enzyme-linked-immunosorbent-assay(ELISA).It was found that GA₁₊₄ contents in the penultimate lamina of Zhen 97 A and Hua 76-49A were lower than that of their restore lines since the beginning of spikelet-differentiation stage.From reduction-division stage,GA₁₊₄ content in young panicle of Zhen 97A became lower than that of its restore line,while GA₁₊₄ content in young pancile of Hua 76-49A was still similar to that of its restore line.It was also found that IAA contents in pancile and penultimate lamina of Zhen 97A were obviously decreased compared with that of their restore lines since spikelet-differentiation stage and the beginning of IAA deficiency in Zhen 97A was much earlier than that in Hua 76-49A.It was proposed that GA₁₊₄ and IAA deficiency would be the main physiological reason in rice cytoplasmic male sterility.

Fifteen high-yield wheat varieties were investigated. A new concept "Variety lodging index" (VLI) involving gravity centre, weight and machinery property of stem, was proposed and the results proved that the VLI could evaluate the lodging resistance objectively and accurately. The stem strength was closely related to variety lodging resistance. These varieties were divided into four types by systematic cluster analysis method based on the differences of their lodging resistance.

Preliminary studies on drought resistance identification of six maize varieties were made by testing water conservation ability of isolated leaves, membrane permeability, water potential, free proline content and root-cap ratio. Quantitation description of the tesing resuit was expresed in five level grade method.

When exposed to water stress induced by PEG, the activity of SOD in the maize seedlings with different drought-resistance lowered at the beginning and then increased and then lowered again; the activity of CAT went up (or almost did not change) at the beginning and then lowered in the strong drought-resistance genotypes but lowered straight in the weak droughtresistance genotypes; the activity of POD lowered apparently in all genotypes. At the sametime, the permeability of plasma membrane increased; the super-microstructures of chloroplasts and mitochondria in the leaves were damaged, and the damaged degree was lighter in the strong drought-resistance genotypes than that in the weak drought-resistance genotypes. The activities of SOD and CAT were negatively related to the damaged degree of plasmalemrna and chloroplasts and mitochondria membrane systems, but positively related to the drought-resistant properties of the genotypes, thus may be used as the biochernical appraisal indexes of drought-resistance of matte. However, the correlation between POD activity and the damaged degree of the membrane systems and the correlation between POD activity and the drought-resistant properties of the genotypes were not apparent.

In this paper,some of yield indices,morphological and physiological characteristics in determining drought resistance of winter wheat were studied.The results showed that drought resistance index was superior to drought resistance coefficient,drought susceptibility index and reducing indices of yield components in determining drought resistance of winter wheat.Index of drought resistance,which represented both the drought resistance and productivity of a cultivar,could be used as a reliable index of drought resistance for stable generation of hybrids.Such indices as length of coleoptile and LAI at elongation stage,which were predicted simple,easy,fast and accurate,could be used to determine the drought resistance of a bulk of genetic resources and segregated individual plant of hybrid progenies.Correlation coefficient was found not significant between drought resistance and leaf proline concentration at grain filling stage,which was not considered to be a suitable index in determining drought resistance of winter wheat.

The presented work studied the physiololgical base of repeated drought method.The paper illustrated that the repeated drought method can fully reflect the drough resistance of crops or varieties by physiological responses of drought resistant varieties in different degree,and the relationship between water supply and demand in soil and plant.The survival rate after undergoing the repeated drought is a comprehensive result of the drought reaction of crops or varieties.It can represent the drought resistance of the tested varieties.This paper also studied the appraisal of drought resistance of wheat varieties in later growing stages.The result of repeated drought method shows the same as that in the field.

Results of pot experiments showed that even slightly water deficit from jointing to flowering stage reduced winter wheat yield, while no yield reduction was found when mild water stress was imposed at turning green stage and milky stage. At different level of water deficit, the yield sensitive index (or coefficient) to water stress varies. After winter wheat undergoes a short term of water stress and when water supply resumed, its growing speed will increase, which is the compensatory growth effect. Then yield reduction is smaller compared with the decreasing in evapotranspiration. The stomatal conductivity and leaf water potential of winter wheat decrease with the decreasing of soil water content when soil moisture is lower than 60% of field capacity, otherwise they don't change very much when it was over 60%.

Heterotic groups were classified by cluster analysis with RAPDs based on 25 important maize inbreds utilised widely in hybrid maize production in China. Ten primers: F₃, O₂₀, A₁₉, M₂, M₆, N₁₁, N₁₂, N₁₉, C₇ and G₁₄, selected from 300 candidate primers from the operon A, to O₃ were used as polymorphic DNA (RAPD) markers for 25 maize inbred lines. Genetic distance among 25 inbreds was calculated and clustered with RAPD markers. The results showed that 25 inbreds lines could be classified into five groups. Groups I consisting of Huangzao 4, 853, Huangye 4, Sizi4, 196, 81515, 404, H21 is included in the Sipingtou heterotic group. Group Ⅱ consisting of 478, 488, 3189, 7922, 8112, Bijian 8, and 5005, is included in the Reid heterotic group. Group Ⅲ consisting of Mo17, Zao 49, and Duo 22, belong to the Lancaster heterotic group. Group Ⅳ only consisting of E28, belongs to the Lda Honggu heterotic group. Group V consists of P78, 9502, 178, P138, 007, and P17. They belong to a new heterotic group different from the above four heterortic groups. The five groups by cluster analysis with RAPD markers conforms to the pedigree method. The results of the study indicated that it is practical to group maize inbred line with RAPDs.

Diurnal change of water use efficiency (WUE) and net photosynthetic rate (Pn) are important processes on crop production and physiological mechanism.The paper analyzed the physio-ecology adaption of spring wheat (Triticum aestinum L.)and summer corn(Zea mays L.)under different water treatment.The result showed that WUE and Pn are markedly influranced by water shortage, the most markedly time stage is in the afternoon(12-16 hr).The main way of Pn change to water shortage in the moring stage is determined mainly by stomata, and in the afternoon stage mainly by non-stomata.Meanwhile, WUE and Pn reaction to water shortage condition not only related to water potential of leaf, but also to the environmental factors, especially to relative humudity(RH)and leaf temperature(Tl).

Three methods of cluster analysis based on phenotype characters,heterosis,and RAPD's molecular markers,were compared in terms of methodology of heterosis grouping with 15 inbred lines used dominantly in commercial hybrid maize production in China.The analysis of phenotype cluster influenced by environment remarkably did not fit with the pedigree of the 15 entries.The heterosis cluster fitted better with the pedigree.RAPD's cluster fitted best with the pedigree for this method is based on plenty of molecular markers without functional phenotypic and multiple effects and epistasis,which are not influenced by growing and development stages and environment.RAPD's cluster is a reliable approach to distinguish the heterosis groups for inbred lines.

The effects of limited irrigation on photosynthetic capacity and water utilization of winter wheat were studied in natural field and rainfall proof trough cultivation.The maximum water consumption by winter wheat per day was in the jointing stage and to flag leaf stage. Limited irrigation can inhibite decrease of leaf area in winter wheat in the period and decrease stomatal resistance of leaves and increase photosynthetic rate of colony and leaf,resulting in photosynthetic capacity was better,water utilization efficiency for economic yield was increased.

Tomato growth is sensitive to water stress.The stem diameter and leaf area were inhibited seriously by water stress.They were all significantly negative correlated with the value of stress.The height and leaf were not inhibited seriously by water stress on condition that it was cultivated in three spikes.The chloroplast content and stomatal resistance increase,and the plant moisture tensiometer,transpiration,photosynthesis and yield decreased with the increase of soil water deficit.According to the study,tomato should grow on water stress about 0.04MPa before the inflating of fruit on condition that it was cultivated in three spikes,then control the stress under 0.02MPa after the inflating of fruit.

Aimed to reduce lose of nitrogen fertilizer(NF)and heighten nitrogen use efficiency(NUE)in summer maize,effects of different application rates of three types of NF(common urea,coated urea and compound fertilizer)on growth and development,NUE of summer maize cultivars Zhengdan958 and Nongda108 were studied in 2004.The main results as follows:Yields of two cultivars increased obviously with the increment of N application rate from 0-180 (kg/ha).The increment effect to yield of compound fertilizer was best under the same application rate,but the difference between three types of NF was not prominent.Grain number per ear of two cultivars increased with the increment of N application rate,and its relationship with type of NF was very weak.1000-grain weight was affected any more by type of NF,and there existed difference between cultivars.LAI,dry matter weight and leaf chlorophyll content increased with the increment of N application rate,and they were heightened more obviously by compound fertilizer and coated urea than by common urea.Compared to common urea,NUE of coated urea and compound fertilizer was higher respectively,but their nitrogen harvest index could not be heightened correspondingly.NUE of three types of NF exist genotype difference.

The effects of different water treatments on the configuration, physiological characteristics and yield of winter wheat were studied. The results showed that the yield of the wheat variety with a higher ability of drought-resistance was higher under water stress, while that of the wheat variety with a lower ability of drought-resistance was higher under abundance of water. The osmotic adjusting ability of the strong drought-resistance wheat variety was higher. The adaptability of the winter wheat to water stress was realized by the osmotic adjusting mechanism. The decrease of the chlorophyll content of the wheat leaves was caused by water stress. but the chlorophyll content of the wheat variety which had a higher ability of drought-resistance decreased less. The sucrose content of the wheat leaves tended to increase with the decrease of the quantity of irrigation. The superoxide dismutase of the leaves of winter wheat that had higher ability of drought-resistance had higher activity under water stress, and its activity was enhanced with the intensity of water stress.

The Changes of four plants'endogenous hormones were investigated during winter periods. The results showed the big difference between the genotypes of the winter wheat and spring wheat, the higher ABA contents in more resistant varieties, the higher GA3 contents in spring wheat; and the higher IAA contents in the genotypes with more resistant to coldness before winter, the more stable Z+ZR contents in the genotype of spring wheat. Thus it could be concluded that there were close relations between the four plants'endogenous hormones and cold resistance in wheat. In addition, the active changes of the endogenous hormones reflected effective metabolism, which did not stop with coldness.

Contents of five kinds of phytohormones in different leaves were tested during filling period. The results showed that the contents of ethylene and ABA in the senescing leaves increased obviously, the contents of Z+ZR and GA₃ in the effective leaves also gothigher during the initial and middle filling periods, but the flag leaf showed complex. Therefore, the phytohormones can be divided into two parts, one was ABA and ethylene that induced and prompted senesce, and the other parts was GA₃ and Z+ZR that maintained the functional leaves and inhibited senesce. IAA showed double functions that maintained growth in the earlier filling period, and that promoted the senescing period in the later filling period. In addition, flag leaf was very special, perhaps due to its important function.

Genetic effects of maize yield component traits were studied by using four populations P₁,P₂,F₁ and F_2∶3 based on major gene and polygene mixed model.The results showed that ear length,ear diameter,ear weight and grain yield/plant were controlled by polygenes.Some major genes controlling kernel number,kernel weight,row number and bare tip length were found.Epistatic interaction between two major genes controlling row number was also detected.It was supposed that characters controlled by major gene and polygene model having lower heritabilities was due to dominant effect.Breeding strategies for yield component traits were discussed.

In this paper,twelve soybean varieties was selected., four physiological indexes related to drought resistance in flowering poding stage were studied in both normal and drought conditions.The results were as follows:The weighed average of subordinate function(D) values of four physiological indexes-relative water content(RWC),relative conductivity,net photosynthesis velocity (Pn) and the activity of superoxide dismutase(SOD) and drought resistance of Soybean was positively significant(r=0 877 3,P0 01).D value could be used to the evaluation of drought resistance for soybean varieties.At last,methods of soybean breeding for high yield and drought resistance were discussed.

The field experiment on ef fect of dif ferent nitrogen applicat ion on y ield, nit rogen distr-ibution and utilizat ion in water wheat under water stress has been processed in Hebei province where is serious dry area from 1997 to 1998. The results show that with the increase of N application, nitrogen utilization efficiency decreased, the treatment ( 225 kg/ha) arrived the highest y ield,and the yield of other treatments applied over the rate decreased. With the increase of N application, N absorbed was mainly distributed in nutrition orgens of plant s in which leaf had the biggestratio. At the same time the harvest index declined in turn.

The variation in morphology and physiology of root systems of wheat genotypes under phosphorus deficiency are very important in practice.The objectives of this study were to determine the early indicators related to phosphorus efficiency and establish a new method of fast and effectively selecting high phosphorus efficiency wheat genotypes.The results showed that the number of root axes and the length of lateral root of P deficient plant were significantly lower(P0.05) than P sufficient plant;The partitioning of assimilates to root was greater than to shoot at low P supply.The length of root axis and root system and the number of lateral roots were sharply increased under low P stress.The differences in number and length of root axis of the given wheat genotypes between the same or different levels of phosphorus supply were significant(P0 05).This suggests that the two traits are controlled by genotype and external factors.The difference in the characteristics of lateral root of the given wheat genotypes was significant only between different levels of P supply.It shows that the traits of lateral root mainly depend on external factors.The differences in root number and root length,and axis length,root angle and activity of acid phosphatase exuded by roots among 6 wheat genotypes were significant(P0 05).The linear relationships between relative grain yield and the interaction of the morphological and physiological tr

Effect of different basal dressing application methods on soil ammonia volatilization was studied by using forced draft enclosure in winter wheat fields.The results indicated that fertilizer placement considerably influenced ammonia volatilization.Surface fertilizer application favored ammonia volatilization.The daytime cumulative volatilization loss amounted to 46.08%,while fertilizer incorporation and surface fertilizer application followed by heavy irrigation both markedly reduced ammonia volatilization,the daytime cumulative loss hardly greater than 10%.The duration of ammonia volatilization with surface application lasted for twelve days,while that with the other two application methods did not exceed six days.

Under soil water stress,osmotic adjustment ability of wheat cultivars with strong drought resistant was 0.41MPa-0.60MPa stronger than that of wheat cultivars with weak drought resistant.Dropping percentage of rilative water content and dropping value of water potential were 6.39-10.74 percentage point and 0.19MPa-0.63MPa less than that of weak drought resistant cultivars.Meanwhile,Photosynthetic capacity was inhibited under soil water stress.However,the degree of inhibition of photosynthetic rate and stomatal conductance of strong drought resistant cultivars were 17.7%-22.5% and 21.06%-23.75% less than that of weak drought resistant cultivars,respectively.Ultrastructure changes of wheat mesophyll cell chloroplast F₂ cultivars were examined under soil water stress.The more severe the soil water stress was,the greater the changes of chloroplast ultrastructure were.The changes were negative correlation with cultivars'drought resistant and osmotic adjustment ability.The morphology of chloroplast under soil water stress changed into circlar.Thylakoid of chloroplast became swollen,matrix lamella became obscure,ultimately,the chloroplast were disintegrated.

The experiment was conducted to study the effect of polysaccharide from atractylodis macrocephalae (PAM) on proliferation of lymphocytes and signaling related molecules like NO, cAMP and cGMP in peripheral blood of piglet. Effects of PAM on proliferation of peripheral blood lymphocytes of piglet were tested by MTT assay. The production of IFN-γ in supernatant were determined by ELISA; the content of cAMP and cGMP were tested by RIA. The concentration of NO was tested by deoxidization assay. The results showed that PAM insignificantly increased proliferation of lymphocytes and the contents of NO, cAMP and IFN-γ in similar dose dependent manner. In conclusion, PAM might perform its immunoregulation functions via signal transduction system in immunocytes by activating immunocytes to release NO and cAMP/cGMP and raise IFN-γ.

The growth and yield of winter wheat were studied on field experiments under different tillage models in North China Plain. Based on tillage models, 6 treatments were set including plough, rotate and zero tillage. The results showed that the tillage fashions greatly affected the ratio of leaf emergence in wheat. The ratio leaf emergence in plough was 27.1%-46.2% higher than that in zero tillage. Because of mulching the soil temperature under zero tillage in turning green stage was lower than that of other treatments, which led to delay 7-10 days of wheat growing season and affect grain filling. Owing to less water evaporation and undeveloped wheat roots under zero tillage, it was easy to leaching of nitrate nitrogen below the soil depth of 100 cm. As a result, both the ratio of nitrogen utilization and the wheat yield decreased.

Rhizosphere and nonrhizosphere soils were sampled from winter wheat field at early growing stage.The total number and genus of the bacteria mineralizing lecithin or dissolving phosphate were measured.It was found that phosphobacteria in rhizosphere soil were higher than those in nonrhizosphere soil.However,the organic phosphobacteria were much more than inorganic phosphobacteria either in rhizosphere or nonrhizosphere soil.There were a lot of diverse genera of phosphobacteria in rhizosphere soil,but a few in nonrhizosphere soil.The main organic phosphobacteria were pseudomonas, and advantageous inorganic phosphobacteria were pseudomonas and Erwinia in rhizosphere.However,there were not any advantageous phosphobacteria in nonrhizosphere soil.

The study was carried out in order to explore the responses of photosynthetic performances of summer maize to nitrogen nutrition. Four treatments were designed as 0, 112.5, 225 and 337.5 kg/ha respectively. The results showed that P(n), chlorophyll content and soluble protein increased with the addition of nitrogen fertilization, but the degradation of chlorophyll and soluble protein delayed. Hill reaction activity and PEPCase activity of nitrogen treatments were higher than that of CK for all periods, and the more the fertilizer input, the larger extent the photosynthetic parameters increased. The influence of fertilizer on P(n) was similar to those on Hill reaction activity and PEPCase activity on the whole, which suggested that fertilizer regulated P(n) by affecting electron transport capability and the photosynthetic carboxylase activity.

Based on the soil fert ility and fert ilizer effect of Beijing brown chao soil in the way of micro-trial of winter wheat-summer maizer continuous cropping, the annual grain yield and the ten-year soil organic matter change show that the crops yield, soil organic matter and soil fertility can be improved significantly by using N P K chemical fertilizers together with organic material under lower soil fertility. The effect can be greater with organic material increasing. The effect of using organic material is best, the second is using wheat straw. The effect of maizer straw combined with chemical fertilizers is similar to that of chemical fertilizers.

Wheat population quality, root system distribution, grain yield and quality were studied under different fertilizer application treatment in the condition of super-high-yielding wheat cultivation. The result showed that wheat population and biomass increased by adding fertilizer application. The root length density decreased as the solum deepening. The root length density increased by adding fertilizer application. The mean root diameter was biggest in 0-10 cm solum, but it had little effect when adding fertilizer application. The root surface area was biggest in 0-10 cm solum, but decreased sharply with the solum deepening.Root area increased by adding fertilizer application and the effect was best when N:P was 1:1. The total root length differed very much in different solum and it was over 50% in 0-10 cm solum. Grain yield and quality increased by adding fertilizer application and the effect was best when N:P:K was 1:1:0.6.

Against a background of a series of serious problems of nitrogen environmental pollution and waste of residue resources in summer maize production in the North China Plain, China Agricultural University and Hohenheim University of Germany have engaged in the Sino-Germany co-operative project, the environmentally acceptable and sustainable agricultural production with high productivity level in the North China Plain since 1999.A part of the results of the research were reported on winter wheat in the Beijing experimental base in 2000-2001. The results were as follows: At the same measuring date, The difference in dry matter weight (DMW) between the three treatments was insignificant; from jointing to flowering, dry matter accumulation rate and DMW of the optimized fertilization were not less than that of the traditional fertilization, from flowering to grain filling, dry matter accumulation rate and DMW of the optimized fertilization were slightly less than that of the traditional fertilization; at the two stages, dry matter accumulation rate and DMW of the optimized fertilization of the optimized fertilization with crop residues were greatest. The difference in yield between the three treatments was insignificant. Nitrogen use efficiency of the optimized fertilization and the optimized fertilization with crop residues were remarkably greater than that of the unreasonable traditional fertilization.