Evaluation Of Growth And Cold Resistance Of Different Juglans Seedlings Based On Water And Fertilizer Regulation

Juglans has strong adaptability,many uses and high oil content.It is an important woody oil,dry fruit and timber tree species.Walnut belongs to Juglans nigra.It is one of the most important nut species in the world and has high economic value.Black walnut belongs to Juglans sect.Rhysocaryon.In recent years,it is increasingly used as an excellent rootstock of Juglans regia.The research on Walnut rootstock cultivation in China started late,Xinjiang is rich in walnut resources,but the rootstock has not been improved.In rootstock cultivation,we should make full use of the coupling effect of water and fertilizer and establish a reasonable model.The research on cold resistance provides a theoretical basis for the breeding of cold resistant varieties and rootstocks.Taking different species of Juglans seedlings as the research object,different water and fertilizer treatments were set.By measuring the growth,photosynthetic characteristics and cold resistance indexes of seedlings,the principal component analysis method,membership function method and cluster analysis method were used for a comprehensive evaluation,and the rootstocks with good resistance of Juglans and the optimal combination of water and fertilizer were selected,so as to provide technical support for the improvement of rootstock breeding of Juglans in Xinjiang,it also provides a theoretical basis for the study of water fertilizer coupling of Juglans seedlings in semi-arid areas.The main research conclusions were as follows:（1）Different water and fertilizer treatments affected the growth of Juglans seedlings,and there were differences in the growth of different species of Juglans seedlings.The order of growth amount of 9 treatments of Juglans seedlings was the same,and 2-1 treatment was the best.The order of seedling growth of the five varieties was as follows:‘LK1’>‘Xincuifeng’>‘Zha 343’>J.microcarpa>J.nigra;The evaluation results of the seedling quality index under different treatments and different varieties of seedlings were consistent with the morphological performance of each plant;Therefore,under different water and fertilizer treatments,2-1（medium water and high fertilizer）significantly promoted the growth of Juglans seedlings.Under different species of Juglans seedings,the growth status was walnut>black walnut.（2）Different water and fertilizer treatments affected the photosynthetic characteristics of Juglans seedlings,and there were differences in the photosynthetic characteristics of different species of Juglans seedings.The order of growth amount of 9 treatments of Juglans seedlings was different,but 2-1 treatment had the highest score.The order of photosynthetic capacity of seedlings of five varieties was as follows:J.microcarpa>J.nigra>‘LK1’>‘Xincuifeng’>‘Zha 343’;Therefore,under different water and fertilizer treatments,2-1（medium water and high fertilizer）significantly improved the photosynthetic capacity of Juglans seedlings.Under different species of Juglans seedings,the photosynthetic capacity was black walnut>walnut.（3）Through correlation analysis,the relationship between indexes and cold resistance is as follows:SS,Pro,SOD,POD,lignin and cellulose are positively correlated with cold resistance;MDA,REC and LT₅₀were negatively correlated with cold resistance.（4）Different water and fertilizer treatments affected the cold resistance of Juglans seedlings,and there were differences in the cold resistance of different kinds of Juglans seedlings.By comparing the principal component analysis and membership function method,it is found that the two conclusions are basically consistent.Under the 9 treatments,2-1 treatment had the highest score.The order of cold resistance of five Juglans seedlings was:J.microcarpa>J.nigra>‘LK1’>‘Xincuifeng’>‘Zha 343’;Cluster analysis was used to evaluate the cold resistance of different kinds of Juglans seedlings.The cold resistance of J.nigra was stronger than that of J.regia;Therefore,under different water and fertilizer treatments,2-1（medium water and high fertilizer）significantly improved the cold resistance of Juglans seedlings.Under different species of Juglans seedings,the cold resistance was black walnut>walnut.（5）Through comprehensive analysis,water and high fertilizer can obtain the best effect on the growth,photosynthetic utilization and cold resistance of Juglans seedlings.The growth of black walnut was slower than that of walnut,but its photosynthetic ability and cold resistance were stronger than that of walnut.Comprehensive analysis showed that the comprehensive ability of black walnut was stronger than that of walnut.Finally,black walnut can be selected as rootstock and cultivated the way of water and high fertilizer（water 15d/time;fertilizer 15 kg/667 m²）.