Effect Of Post-Anthesis Shading On Yield And Quality Of High-Quality Japonica Rice

Solar radiation is the energy base of life activities and is one of the important agricultural climate resources.It plays an important role in crop growth.In the past 30 years,the total solar radiation in China has declined.Rice plays an important role in increasing grain production and stabilizing production.With the economic development and the improvement of people’s living standards,the market demand for high-quality rice is growing.Previous studies on the effects of solar radiation on rice growth have focused on research on yield,lodging and carbon and nitrogen metabolism,while studies on the quality of high quality japonica rice are relatively rare.In this experiment,two representative high-quality japonica rice varieties of Huaixiangjing 15 and Nanjing 9108 were used as materials.The shading was used to control the light conditions after flowering,and no shade(CK)was set in the mature period from 10 days after the heading.The shading rate is 40%(SI)and the shading rate is 60%(S2).By analyzing the effects of ecological conditions on the dry matter production characteristics,leaf photo synthetic physiology and rice yield and quality,the response characteristics of high quality japonica rice varieties to light were explored,and the theoretical mechanism for revealing the response mechanism of high quality rice quality to light was proposed..The main conclusions of this study are as follows:1.Post-anthesis shading reduces the dry matter accumulation of various organs of high-quality japonica rice,resulting in a weakening of dry matter production capacity.After shading,the accumulation of dry matter in stems,leaves and panicles and the accumulation of total dry matter in the above-ground(except the accumulation of leaf dry matter of Nanjing 9108 in the mature stage)showed a significant downward trend,while the two different shading treatments(except the accumulation of dry matter of Nanjing 9108 on the 25th day after heading).After shading,the distribution index of Huaixiangjing 15 has an upward trend,while that of Nanjing 9108 is a downward trend,but there is no significant difference.The leaf allocation index Huaixiangjing 15 has risen and fallen,Nanjing 9108 has an upward trend and S2 Significantly different from CK,the spike distribution index of both varieties showed a downward trend,but there was no significant difference.The dry matter accumulation decreased significantly after shading,and the proportion of dry matter quality after the heading increased significantly.2.Post-anthesis shading mainly reduced the net photosynthetic rate,stomatal conductance,transpiration rate,top 3 leaf SPAD value and top 4 leaf SPAD value of high quality japonica rice,which in turn affected the photosynthetic physiological characteristics of leaves.The net photosynthetic rate,stomatal conductance and transpiration rate showed a significant decline after shading,while there was no significant difference in intercellular carbon dioxide concentration.After the shading,the SPAD value of the canopy(except for the SPAD value after 6 days of shading in Nanjing 9108)showed a different degree of decline,and the decrease from the 18th day after shading was more obvious,while the decrease was most obvious after the 30th day of shading.The shading had little effect on the SPAD value of the top 1 leaf of Huaixiangjing 15.Except the SPAD value of Huaixiangjing 15 after 24 days of shading,the SPAD values of top 2,top 3 and top 4 had different degrees of decline.And after 18 days of shading,the downward trend is more obvious,and it is relatively more obvious after 30 days of shading,and the top 4 leaves fluctuate the most.After 6 days of shading,the SPAD values of the top,top 3 and top 4 leaves of Nanjing 9108 increased.After 12 days,18 days,24 days and 30 days of shading,except for 12 days after S2 shading in the top 1 leaf,other There were different degrees of decline,and S1 and S2 were significantly different from CK after 24 days and 30 days of apex,top 3 and top 4 leaves.3.Post-anthesis shading mainly reduced the seed setting rate,which led to a decline in rice yield;the decline in rice quality was mainly the result of a combination of processing quality,appearance quality,cooking and eating quality and nutritional quality.After shading,both varieties showed a significant downward trend in both theoretical and harvested yields.The theoretical yield reduction was 26.21%-34.10%,and the harvested.yield decreased by 26.82%-34.20%.There was no significant difference in the number of effective panicles between the two varieties after shading.The number of grains per panicle,seed setting rate and 1000-grain weight(except Nanjing 9108)There are significant differences,showing varying degrees of downward trend,of which the seed setting rate has the greatest impact,with a decrease of 15.51%-22.29%.After shading,the brown rice rate and polished rice rate of the two varieties showed a significant downward trend,and the whole milled rice rate showed a significant upward trend;after shading,the grain length,aspect ratio,chalkiness and chalkiness increased in different degrees,but The difference in significance was different.The grain width and transparency varied with the variety.After shading,the amylose content and protein content of the two varieties showed a significant upward trend,and the taste values showed a significant downward trend.The highest viscosity and hot paste of the two varieties after shading Viscosity,cold paste viscosity and disintegration values all showed a significant downward trend,and the alkalinity value was a significant upward trend.