Abstract:
【Objective】 To study the photosynthetic characteristics, dry matter accumulation, yield to drought stress in the hope of providing a theoretical basis for spring irrigation schedule of winter wheat.
【Methods】 A pot culture experiment was conducted with four soil moisture gradients containing full irrigation (CK), mild drought(T
1), moderate drought(T
2) and severe drought(T
3) in winter wheat at jointing stage in the study.
【Results】 The results showed that highest leaf water use efficiency of winter wheat at jointing stage was observed in T
2.The trend of net photosynthetic rate, transpiration rate, stomata conductance, intercellular carbon dioxide concentration and chlorophyll content decreased with increasing of drought stress.The rank of the effect of drought stress on fluorescence parameters including
Fv/Fm,
Fv/Fo and
Fm/Fo was that: T
1 > CK > T
2 > T
3.Compared with CK, dry matter accumulation of underground increased by 11.8% and 3.0% in T
1 and T
2, however, which decreased by 4.0% in T
3.The proportion of underground dry matter in T
1, T
2 and T
3 treatment increased by 4.0%, 6.0% and 11.0%, respectively.With respect to the performance of irrigation water use efficiency, it was the highest in T
1 and the grain yield increased slightly.In terms of grain yield, it was significantly lower than CK by 14.8% and 42.4% (
P<0.05)both in T
2 and T
3, in turn, which increased somewhat in T
1.According to the results of Pearson correlation analysis, leaf water use efficiency was significantly (
P< 0.05) positively correlated with total dry matter accumulation, grain yield and irrigation water use efficiency, furthermore, a significant(
P< 0.01) positive correlation was detected between leaf water use efficiency and dry matter accumulation of aboveground, but a significant(
P< 0.01) negative correlation was found between leaf water use efficiency and intercellular carbon dioxide concentration.
【Conclusion】 Under the mild drought treatment, the jointing winter wheat is adapted to the drought environment by regulating photosynthesis and increasing the underground accumulation of some dry matter and its proportion, thus improving the grain yield and irrigation water utilization efficiency.However, with the aggravation of drought stress, the photosynthetic rate of winter wheat decrease obviously, which lead to reducing dry matter accumulation and ultimately lead to the reduction of winter wheat yield.