Abstract: 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.

Key words: Soil moisture, Photosynthetic rate, Transpiration rate, Threshold response, Root/shoot ratio

CLC Number: 

• S512.101