Effects of drought stress during flowering on post-flowering dry matter accumulation and transfer and yield of different maize cultivars

【Objective】To analyze the influence mechanism of drought stress during flowering on post-flowering dry matter accumulation and transfer and yield of summer maize, and provide reference for summer maize drought resistant cultivation.【Method】Conducted a field study under a rain exclusion shelter from 2018 to 2019, investigated the effects of drought stress during flowering stages on plant morphology, leaf area index, dry matter accumulation and distribution after flowering and grain yield of maize. Two maize cultivars(ZD958, a drought-tolerant cultivar, and WK702, a drought-sensitive cultivar) were subjected to four drought stress treatments respectively, including CK(control, well watered during the whole growth period), T1(drought stress before flowering), T2(drought stress after flowering), and T3(drought stress during flowering). 【Result】The results showed that drought stress before flowering inhibited the growth of plant height, ear height, stem diameter and leaf area, while drought stress after flowering had less effect on plant height, ear height, stem diameter and leaf area, but had greater effect on the decline of leaf area index in later growth period. Drought stress during flowering not only significantly reduced the dry matter accumulation(P<0.05, the same below), but also inhibited the transport of dry matter from vegetative organs such as stems and leaves to grains, reduced the transport amount and transportrate of dry matter from vegetative organs as well as their contribution rate to grain yield, thus reducing the proportion of dry matter distribution in grains at the maturity stage. The effect of drought stress before flowering on ear length, ear diameter, grain number per ear and 100-grain weight in summer maize was greater than that of drought stress after flowering. Drought stress during flowering significantly reduced grain yield of summer maize. Decline in grain yield was the largest under drought stress during flowering, the decline in grain yield under drought stress before flowering was larger than drought stress after flowering. Compared with the control, the grain yield of T1, T2 and T3 in drought-tolerant cultivar ZD958 were 20.1%, 15.6% and 35.9%, respectively, while were 32.3%, 19.3% and 51.3% in drought-sensitive cultivar WK702, respectively.【Conclusion】Drought stress during flowering affects plant morphology, effective photosynthetic area, dry matter accumulation and transport of summer maize after flowering to various extents, which causes significant decrease of maize yield. The inhibition of dry matter accumulation and transport after flowering in drought-sensitive cultivar WK702 is significantly higher than that in drought-resistant cultivar ZD958.