Effect of water and fertilizer coupling on photosynthetic characteristics and quality in walnut

【Objective】To provide theoretical basis for walnut high yield cultivation.【Methods】Walnutvariety‘Xinxin2'was used as material to study the effect of different water and fertilizer coupling on pho-tosynthetic characteristic and quality in Xinjiang.【Results】The results showed that during whole growthperiod the leaf net photosynthetic rate of walnut increased at first and then decreased; stomatal conduc-tance and transpiration rate showed“high-low-high-low”change trend; the initial fluorescence(F₀),maximal fluorescence(Fm),photochemical efficiency of PSⅡ(Fv/Fm),total photochemical PSII quan-tum Yield(Yield)and electron transport rate(ETR)were higher at the stone hardening stage than at theoil conversion stage. The coefficient of photochemical quenching(QP)at the stone hardening stagechanged ranges from 0.75 to 0.86; at the lower level of fertilizer,the coefficient of photochemical quench-ing(NPQ)increased with the increase of irrigation water. The reducing sugar,fat,cellulose content andIodine value were the lowest,while protein content was the highest in the lower level of water and fertiliz-er 2-II treatment. In the high level water and high fertilizer treatment with irrigation quota 3.14 m³·plant^-1,application of 2.661 kg·plant^-1could increase production of walnut and complete fruit number; water andfertilizer coupling treatment could decrease the thickness of the nuclear shell.【Conclusion】The water andfertilizer coupling treatment can improve the quality of walnut and photosynthesis.