Study On Late Frost Resistance And Cultivation Techniques Of Walnut

Walnut(Juglans regia)is one of the main cash crops in China.It is an important tree species for converting farmland to forestry in recent years.Shanxi is a big walnut province with rich germplasm resources.However,the problems of "weak cold resistance","optimum grafting temperature" and "unclear pruning time" caused by many years of introduction of walnut need to be solved urgently.In this experiment,Li Pin No.2,Liaoning No.1,Zhonglin No.1 and a 30-year-old late frost-resistant walnut plant were observed and found in Fenyang in recent five years.The growth index and cold-resistant index were investigated at the present stage(browning rate,electrical conductivity,MDA,SOD,POD,PRO were detected by five temperature gradients: normal temperature,0?,-2?,-3?and-4?.Assessment of cold resistance;Group grafting of 80 seedlings at different temperatures,continuous observation and record on 8days after grafting,the optimum temperature for Walnut Grafting was obtained;Winter pruning experiment was conducted to compare 8 groups of target trees with those without pruning,which had the same site conditions,the same age and the same varieties,and to compare their same plant tissues(xylem and phloem).The content of nutrients(soluble sugar and protein)contained in walnut pruning was determined from January 20 to March 30 to determine the optimum period for walnut pruning in winter.The effects of Fertilization on the yield of Jinlong 1,Zhonglin 1 and Li Pin2 walnut varieties in Fenyang area were analyzed,and the relationship between the output value of walnut per hectare and fertilizer input was found by fitting regression.At the same time,the effect of different harvesting time on the kernel yield of walnut was discussed.The conclusions are as follows:1.The results of cold resistance research of walnut are as follows: the cold resistance of late frost resistant plants is: late frost resistant plants > Zhonglin 1 > Liaoning 1;and-2? is the semi-lethal temperature of Zhonglin 1 and Liaoning 1,and-4?is the semi-lethal temperature of late frost resistant plants;for the same varieties,the cold resistance of plant tissue is: phloem cold resistance > leaf cold resistance > bud cold resistance > young fruit cold resistance > flower cold resistance;The cold resistance of floral organs of the same cultivar was as follows: male flower was more resistant to cold than femaleflower;POD content in leaves of the same cultivar was 2-3 times higher than that of buds and fruits.2.The optimum temperature of Walnut Grafting in Jinzhong area is about 28 C.The survival rate of walnut will be decreased when the temperature is lower than 24? or higher than 32?.3.The optimum time for winter pruning is from January 31 to February 11.This time period has less bleeding,and plants can preserve more nutrients without causing a large loss of nutrients.March is the peak period of bleeding,which is not suitable for pruning walnut trees.4.The output value of walnut varieties,Jinlong 1,Zhonglin 1,Li Pin2 and real walnut with tree age less than 20 years were positively correlated with fertilizer input.The earliest harvesting time of early-maturing varieties Jinlong 1,Jinlong 2,Liaoning 1 and Zhonglin 1 was around September 8 in Fenyang,and the highest rate of kernel yield was 64.5%.The best harvesting time of late-maturing varieties Li Pin 2 was September 15,and the rate of kernel yield was 61.0%.