Abstract: This study aimed to investigate the effect of different water stress stages and duration on rice starch synthesis and yield. With rice cultivars Yixiangyou 2115 as experimental materials, the content of soluble sugar and starch, the activities of enzymes related to starch synthesis, and yield of a rice grain under four water management modes traditional flooding(CK, 0 kPa, 1-3 cm water layer), light water stress(LD, (-20±5) kPa), moderate water stress(MD, (-40±5) kPa) and severe water stress(SD, (-60±5) kPa) at booting stage, flowering stage and filling stage respectively were analyzed in 2018-2019. The results showed that:the content of soluble sugar and sucrose were decreased and the content of amylose and total starch was increased under light water stress at the booting stage, flowering stage, and filling stage. The largest drop had reached 33.7%, 14.3% and the maximum raise had reached 2.4%, 4.4% respectively. On the contrary, moderate water stress and severe water stress had the opposite effect on them;The activities of enzymes related to starch synthesis such as AGPase, SSS, GBSS, SBE, and DBE all showed the variation tendency of falling after rising under four water management modes at different stages. Enzymes activities and their peak value were enhanced under light water stress at the middle and late filling stage, but moderate water stress and severe water stress had the reverse effect on them. Light water stress with a higher seed setting rate increased the yield by 3.1 percentage points only at the filling stage compared with traditional flooding. 1000-grain weight was increased at all stages under light water stress which the maximum raise had reached 3.7%. However, water stress at the booting stage was not favorable to the yield. Light water stress at the filling stage and flowering stage increased the yield by 0.8%, 9.3% respectively. In conclusion, light water stress at the flowering stage and filling stage could improve the activities of key enzymes for starch synthesis and the synthesis and accumulation of starch in grains of Yixiangyou 2115, thereby increasing the yield. Compared to light water stress at the flowering stage, light water stress at the filling stage had a higher increasing amplitude of yield.

Key words: Rice, Water stress, Booting stage, Flowering stage, Filling stage, Key enzymes for starch synthesis, Yield

CLC Number: 

• S511.03