Effect Of Water And Fertilizer Coupling On Growth And Fertilizer Utilization Of Young Walnut Trees

In this study,the effects of water and fertilizer coupling on growth index,physiological index,nutrient absorption and distribution and fertilizer utilization rate of young walnut trees were studied by pot experiment.The response of young walnut trees to the coupling effect of water and fertilizer and the optimal combination of irrigation and fertilization were proved.The main conclusions were as follows:1.The growth of walnut new shoot diameter,length and walnut dry matter increased with the increase of irrigation water and fertilizer.Under high fertilizer conditions,increasing the amount of irrigation could significantly promoted the growth of walnut basal stems.The effects of irrigation,fertilization and water-fertilizer interaction on walnut plant height were not significant.F3W3 treatment(high fat and high water combination)significantly promoted the growth of young walnut shoots.F3W2 treatment(High fat and middle water combination)significantly promoted the basal stem growth and increased the growth of walnut.2.Coupling of water and fertilizer had some influence on physiological indexes of young walnut trees.Under the condition of water and fertilizer coupling,the content of malondialdehyde in walnut leaves generally decreased with the increase of irrigation and fertilization.The content of MDA in walnut leaves of F1W3 treatmen(low fat and high water combination)and F2W3 treatment(medium fat and high water combination)was significantly lower than that of other treatments,and there were no significant differences between the two treatments.A moderate amount of fertilizer could increased the peroxidase and catalase activities in the leaves,and alleviated the water stress caused by less irrigation.When the amount of fertilizer was small,the low irrigation amount significantly reduced the chlorophyll content of the leaves.3.Coupling of water and fertilizer also had a certain effect on the photosynthetic characteristics of young walnut trees.The monthly changes ofnet photosynthetic rate(Pn)and transpiration rate(Tr)of walnut leaves from June to August showed a trend of first increase and then decrease with the growth period,and reached the peak in July.The changes of Pn and Tr in walnut leaves under different treatments were basically the same in different months.The leaves of F2W3 treatment(medium fat and high water combination)had the highest Pn and Tr,and the leaves of F1W3 treatment(low fat and high water combination)had the highest water use efficiency(LWUE).The changes of net photosynthetic rate(Pn)and transpiration rate(Tr)of walnut leaves in different treatments were different in the daytime.The changes of Pn and Tr in high-fertilizer levels in the daytime showed a clear double-peak curve.4.With the increase of irrigation and fertilization,the N,P,and K absorption of the whole walnut young plant showed an increasing trend.At low water levels,the effects of fertilizer application on N and K fertilizer use efficiency of young walnut trees were not significantly different.F1W3treatment(low fat and high water combination)had the highest N,P,K fertilizer utilization efficiency.Considering comprehensively new shoot growth,biomass,leaf water use efficiency and fertilizer use efficiency of young walnut trees,F1W3treatment(soil moisture was controlled in 80% of field capacity,N-P2O5-K2 O were controlled at 5-2-3g·tree-1)achieved the best water-fertilizer coupling model for efficient use of water and fertilizer.