Effects Of Regulated Deficit Irrigation On Growth And Yield Of Rice

The experiments were carried out with Liangyoupeijiu and Chunjiang 012 in the treatments of standing water(check), 100%, 80% and 60% of saturated soil in the period of productive tiller, unproductive tiller, panicle initiation, grain filling in the pot, and with Nei2you 6 and II you 7954 in field in the treatments of different soil moisture in China National Rice Research Institute in 2003-2004 to study the effects of soil water regimes on growth and yield of rice. The main results were as follows:With the decrease of soil water moisture, the average temperature on soil surface and under 10cm layer of soil increased in a daytime that resulted in more temperature difference and value of redox in soil increased.During productive tillering period, compared to check the length of rice root was improved under light water deficit, and was restrained under middle water deficit. Recovering irrigation after water deficit, root growth was compensated. The effects of water deficit on root number were different because of variety. The root number per stem in Liangyoupeijiu was reduced under water deficit compared to check, root growth was compensated after recovering irrigation. The decrease of the root number per hill partly resulted from the decrease of tiller per hill. Middle water deficit didn't affect the root number per stem in Chunjiang 012 obviously; the root number per hill was decreased because of the lack of tiller mainly.During unproductive tillering period, the growth of root was improved under moderate water deficit, the ratio of root to shoot increased under water deficit, and thedegree is middle water deficit light water deficit severe water deficit. During panicle initiation period, the root weight decreased under water deficit insufficiently, water deficit restrained shoot more greatly than root. Sensitivity of root weight to water deficit was ranked by the following sequence: effective tillering stage panicle initiation period ineffective tillering period.The effect of water deficit on superficial roots growth was different in variety. Nei2you 6 is more sensitive than II you 7954 to soil water deficit. Superficial roots growth was slightly promoted by light water deficit, but was constrained by middle water deficit.α -NA-oxidizing ability of rice roots and bleeding rate at flowering under water deficit increased. Bleeding rate of II you 7954 increased much than that of Nei2you 6 under water deficit..Water deficit more greatly effected on the accumulation and translocation of dry matter of Nei2you 6 than that of II you 7954. The accumulation of dry matter was improved under moderate water deficit. Under severe water deficit, transmission rate of dry matter to panicle is low than check in Nei2you 6, however high in II you 7954. During unproductive tillering period, water deficit caused the accumulation of dry matter decreased, after recovering irrigation; the accumulation of dry matter could be compensated partly.Under water deficit, plant height decreased, leaf became shorter, and the expansion rate of new leaf growth was slower. Photosynthetic rate increased under light water deficit, but was decreased under severe water deficit.For Liangyoupeijiu water deficit was imposed during productive tillering period, panicle number per hill dropped, during panicle initiation, kernel per panicle and spikelet fertility dropped and during early grain filling stage, spikelet fertility and 1000-grain weight decreased. For Chunjiang 012 water deficit was imposed during productive tillering period, panicle number per hill dropped, during early panicleinitiation kernel per panicle decreased, and during late panicle initiation and early grain filling stage, 1000-grain weight dropped. Spikelet fertility of Chunjiang 012 didn't decrease obviously under water deficit. During unproductive tillering period, spikelet fertility and yield were improved under moderate water deficit, but were decreased under severe water deficit markedly.It was recommended that for the consideration of yield and water saving, 80% of soil saturate...