Abstract:

In order to identify the differences in source-sink relationships among different types of barley and the main source-sink indexes affecting yield,four barley materials with large leaf area differences,GP6,GKP7,GK6 and C2-1,were selected to study the differences in photosynthetic characteristics,dry matter,soluble carbohydrates,and filling characteristics and their relationships with yield in 7—28 d after anthesis.The results showed that the length-to-width ratio of flag leaves of GK6 and GKP7 was lower than that of GK6 and C2-1,while the chlorophyll content,photosynthetic rate and soluble sugar of flag leaves and penultimate leaves were higher.The chlorophyll content of flag leaves and penultimate leaves of GKP7 decreased the most,while the decrease of GK6 and C2-1 was smaller.During the early stage of grain filling,the dry weight of leaves and stem sheaths in GK6 was the highest,but the dry matter decreased the most during the filling process.The dry weight of GP6 and GKP7 was lower than that of GK6 and higher than that of C2-1,but the decrease was relatively small throughout the filling period;the grain rapid weight gain time of GP6 and GKP7 was 7—21 d longer than that of GK6 and C2-1(7—14 d),and the average filling rate(R) and time of maximum filling rate(Tmax)of GP6 was the highest,and the soluble sugar content of stem sheath and grain was lower than that of C2-1 at the early filling stage,which was higher than that of other materials.GKP7 filling active periods(D) and maximum filling rate(Rmax)were the highest,soluble sugar content in stem sheath was lower than GP6 and C2-1 at the early grout stage,and higher than other varieties at the later grout stage of leaf and stem sheath.The soluble sugar content in all organs of GK6 was low,and the soluble sugar content in stem sheath and grains was the highest at the early stage of C2-1 filling,but the content decreased rapidly at 7—14 d and was lower at the later stage of filling.The number of thousand grains weight and yield of GK6 and GKP7 were significantly higher than those of GK6 and C2-1,and the sink capacity of GK6 and C2-1 was smaller.Grain weight per spike/leaf area was GKP7>GP6>C2-1>GK6.Correlation analysis showed that the ratio of flag leaf length to width was negatively correlated with yield,and the stem sheath and leaf dry weight,leaf soluble sugar content,number of grains per spike,grain weight per spike/leaf area were positively correlated with yield at maturity.The chlorophyll content and photosynthetic rate at 7 d after anthesis,the grain dry weight at 14—28 d after anthesis,R and Rmax were positively correlated with yield.In summary,GKP7 has the most reasonable source-sink relationship,with GP6 ranking second,C2-1 source and sink are small,and GK6 source is large and sink is small.The ratio of flag leaf length to width,chlorophyll content and photosynthetic rate at the beginning of filling,grain dry weight,maximum filling rate and average filling rate can be used as the main indexes for high yield breeding.

Key words: Barley, Source-sink, Photosynthetic characteristics, Grain filling rate, Yield