| There was obvious "diapause period" after flowering of inferior spikelets in large-panicle japonica rice,which often resulted in later filling initiation and poor filling of inferior spikelets,which seriously restricted the high yield of large-panicle type rice.In order to study the physiological changes of carbon metabolism during the filling initiation process of inferior spikelets in large-panicle japonica rice,this test used large-panicle japonica rice W1844 and CJ03 as materials,set two shading treatments and two density treatments,they were shading 70%(S1),shading 90%(S2),every other row slice off whole row of plants(D1),every other row slice off whole row of plants and tillers only retained main stem(D2),not to do anying for control treatment(T0)total five test treatments.The main research results are as follows:(1)Stem sheath NSC significantly affected the grain filling of inferior spikelets in large-panicle japonica rice.Shading treatment significantly reduced the content of stem sheath NSC and sugar flower ratio before heading,and 1000-grain weight and seed setting rate of inferior spikelets,while density treatment significantly increased(p<0.05).At the same time,there was a curve correlation of Y=(a+bx)/x between sugar flower ratio before heading and the 1000-grain weight and seed setting rate of inferior spikelets.The correlation coefficients(R2)of 1000-grain weight and seed setting rate of W1844 inferior spikelets were 0.970 and 0.964,respectively.And the correlation coefficients(R2)of 1000-grain weight and seed setting rate of CJ03 inferior spikelets were 0.986 and 0.963,respectively,all reaching the extremely significant level(R20.05=0.771,R20.01=0.919).(2)Stem sheath NSC before heading can regulate the filling initiation period of inferior spikelets in large-panicled japonica rice.Based on the analysis of grain weight and grain morphological,compared with the control treatment(inferior spikelets filling initiation period was 5-10 d after flowering),shading treatment(S1)delayed the filling initiation period of inferior spikelets for 5 d,which was 15-20 d after flowering;density treatment(D2)advanced for 5 d,which was 5-10 d after flowering.Compared with the control treatment,the shading treatment(S1)reduced the Initial grain filling potential at the initial stage of grain filling,maximum grain filling rate and average grain filling rate,extended the time to reach the maximum grain filling rate and the active grain filling period,and at the same time,the peak of grain filling rate appeared later and the final grain weight was lower.While density treatment(D2)is the opposite.(3)In the filling initiation process of inferior spikelets in large-panicle japonica rice,compared with inferior spikelets in diapause period,inferior spikelets in filling period had lower soluble carbohydrate(sucrose)and higher starch content in endosperm substance dynamics.There was lower ATP content and higher ATP activity in the energy change.In the key enzymes of sucrose metabolism and starch metabolism of SuSase,AGPase and SBE are highly activity,and these three enzymes play a major role in the filling initiation process of inferior spikelets in large-panicle japonica rice. |
