| The heading and flowering stage of rice is very sensitive to temperature and moisture.During this period,the physiological characteristics of rice will be greatly changed,and the yield significantly reduced if it is subjected to high temperatures.This research selected the heat resistance difference variety Yixiangyou5979(heat type)and Jingyou127(thermal)as experimental material,used potassium fertilizer and silicon fertilizer as basic fertilizer and combination,took natural temperature as a contrast,and set up high temperature stress treatment(average temperature 30?35?)to discuss the effects of rice floral organ,morphology and physiological and biochemical changes of photosynthetic characteristics and yield under high temperature stress during heading and flowering period;At the same time,we also studied the effects of potassium and silicon combination on the material accumulation and transportation,physical and chemical properties of stem and sheath,and lodging resistance of rice in 22 d after heading determination of snapping resistance and stem sheath physicochemical properties,dry matter weight and the content of Total potassium and SiO2 on stem and sheath at maturity.The main results are as follows:1.Under high temperature stress,the anther dehiscence was blocked,the pollen viability,the seed setting rate and the anther soluble protein content were decreased,the content of anther heat stable protein was increased,there were significant differences between different varieties.Anther morphology,cracking rate and diameter of heat resistant variety Yixiangyou5979 were not only significantly higher than Jingyoul27,but also the content of soluble protein and heat stable protein content were higher,and the soluble protein content decline of Yixiangyou5979 was less 11.22%than Jingyoul27,but the heat stable protein content increase of Yixiangyou5979 was more 17.55%than Jingyoul27 under high temperature stress The rice anther morphology,diameter,pollen viability,soluble protein content and heat stable protein content of the treated potassium were higher than that of silicon,and the D2(K 1.12 g-pot-1,Si 1.12 g·pot-1)treatment was the highest,D1(K 1.68 g·pot-1,Si 0.56 g-pot-1)was secondary in potassium and silicon fertilizer combination.2.The photosynthetic capacity of flag leaves of rice under high temperature stress was decreased.Chlorophyll a,b content and photosynthetic key enzyme Rubisco Mg2+-ATP and Ca2+-ATP activity with the extension of stress time showed a downward trend after high temperature stress,and Yixiangyou5979 were higher 15.79%,21.48%,14.78%,30.88%,39.38%than Jingyoul27,and a decline of Yixiangyou5979 were less 3.20%,7.35%,6.55%,19.93%,25.61%than Jingyou 127,respectively;In the treatment of potassium and silicon,the photosynthetic capacity of potassium fertilization was higher than that of silicon treatment,and was higher than that of the treatment without potassium and silicon,and the photosynthetic ability of D2 treatment was the slowest decline and the strongest;Chlorophyll a,b content,Rubisco enzyme activity and Mg2+-ATP and Ca2+-ATP enzyme activity showed a decreasing trend after the end of high temperature treatment.These showed that heat resistant varieties were more than heat sensitive sense,high temperature promoted the rice flag leaf senescence,and potassium by affecting the photosynthetic capacity and photosynthetic system activity affected photosynthesis,improved the efficiency of photosynthetic phosphorylation,formed more ATP to provide energy for the plant 'and promote the metabolism and protein synthesis,silicon reduced leaf temperature and stabilized chloroplast thylakoid membrane under high temperature stress,and the combined application of potassium and silicon fertilizer can delay plant senescence,maintain higher photosynthetic characteristics,and reduce the negative effects of high temperature on crop growth in a certain extent,so as to improve the heat resistance ability of rice under high temperature.3.Under high temperature stress,the 1000 grain weight,seed setting rate and the number of grains per panicle were decreased,and caused the yield reduction significantly.The yield of Yixiangyou5979 and Jingyoul27 were decreased by 8.04%and 12%after suffering high temperature,but Yixiangyou5979s,yield were still higher 8.98%than Jingyou127;In the treatment of potassium and silicon,the yield were from high to low is D2(K1.12 g·pot-1 Si 1.12 g-pot-1),D1(K 1.68 g·pot-1,Si 0.56 g·pot-1),CK1(K1.12 g-pot-1,Si0g·pot-1),D3(K 1.68 g·pot-1 Si 0.56 g-pot-1)?CK2(K0g-pot-1,Si1.12·gpot-1)?CKO(no fertilizer Kand Si),and the yield of each treatment was decreased by 0.92%,3.11%,12.22%,10.27%,14.34%,and 21.93%,respectively.The results showed that there were significant differences in the yield of different heat resistant varieties,and heat resistant varieties were less affected by high temperature,and the number of grains per spike and 1000 kernel weight were higher than heat-sensitive variety;The effects of potassium and silicon on yield from high to low were potassium treatment,silicon treatment,no potassium and silicon treatment,the yield of D2 and D1 deal decreased slightly after high temperature stress.4.There was a significant difference between varieties that the lodging resistance of Yixiangyou5979 was better than Jingyou 127.The influence of Potassium fertilizer on rice lodging resistance was greater than that of Silicon,and Silicon fertilizer applied too much was not conducive to the absorption of Silicon and Potassium in rice and the increasing lodging resistance.In this experiment,rice lodging resistance was the worst without Potassium,poor in the case of Silicon fertilizer excess.Dl and D2 were the better deal because of a maintaining high level of stem-sheaths dry matter in full heading,the optimized distribution of internodes,a notable increase in the physical strength of basal internodes,the SiO2 and total Potassium content in stem-sheaths,which enhanced the lodging resistance. |
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