根际饱和溶解氧对水稻分蘖期光合及生长特性的影响OA北大核心CSTPCD

[Objective]Studying the regulatory effects of rhizosphere saturated dissolved oxygen(RSDO)during the tillering stage on rice photosynthesis and chlorophyll fluorescence parameters is of great significance for improving rice light energy utilization efficiency and optimizing rice oxygen nutrition cultivation theory.[Method]This study conducted a hydroponic experiment using three ecological types of rice varieties,namely lowland rice,deep-water rice,and upland rice,as experimental materials.Two treatments,rhizosphere saturated dissolved oxygen(RSDO)and natural growth(CK),were set up to measure chlorophyll fluorescence parameters,photosynthetic characteristics,and dry matter accumulation during the rice tillering stage.[Result]Under the conditions of rhizosphere saturated dissolved oxygen,the leaf light response curves of lowland rice and deep-water rice decreased.When the light intensity exceeded 500μmol/(m2 s),the difference in curves with the control group increased.The fitting of the light response curve indicates that rhizosphere saturated dissolved oxygen reduces the maximum net photosynthetic rate(Pnmax),apparent quantum efficiency(Q),dark respiration rate(Rd),and light compensation point(LCP)of rice leaves.The maximal photochemical efficiency(Fv'/Fm'),the actual photochemical efficiency(ΦPSⅡ),electron transfer rate(ETR),and photochemical quenching coefficient(qp)of the three rice varieties under RSDO were lower than those of CK,while the non-photochemical quenching(NPQ)and 1-qp were increased.Rhizosphere saturated dissolved oxygen can increase the nighttime respiration rate(Rn)and intercellular CO2 concentration(Ci)of rice.The leaf chlorophyll a,chlorophyll b,and total chlorophyll contents of three rice varieties all showed RSDO＜CK,while carotenoid content and relative conductivity showed RSDO＞CK.The saturated dissolved oxygen in the rhizosphere significantly reduced the aboveground dry matter mass and leaf area index of lowland rice and deep rice,with a decrease of 12.6％,9.4％,and 9.2％,6.6％,respectively,compared to the control.There was no significant difference between the treatments of upland rice varieties.[Conclusion]RSDO inhibits the synthesis of photosynthetic pigments in rice leaves,reduces leaf PSⅡperformance and light energy utilization efficiency,which is not conducive to early rice growth.Compared to lowland rice and deep-water rice,upland rice has better adaptability to RSDO.