Water and nitrogen input optimization for jujube trees under surge root irrigation based on weighted grey correlation model

In order to obtain the optimal input of water and nitrogen(W&N)suitable for the jujube trees in Northern Shaanxi,12 treatments had been set in the demonstration base of micro-irrigation jujube tree of Mizhi County in 2014-2015 through field experiment of jujube trees under surge root irrigation(SRI),in which three soil moisture levels(high moisture level W1:60%-85%θ,middle moisture level W2:50%-75%θ,low moisture level W3:40%-65%θ)and four nitrogen input levels(high nitrogen F75:0.75 kg/plant,middle nitrogen F50:0.50 kg/plant,low nitrogen F25:0.25 kg/plant,no nitrogen F0:0.00 kg/plant)were set.Through analyzing the effects of different W&N inputs on the yield,net income(NI)and W&N utilization efficiency(WUE and NUE)of jujube trees and establishing a weighted grey correlation model,the optimization of W&N input for jujube trees could be achieved under SRI.Results showed that different W&N inputs had significant influences on yield,NI,WUE and NUE.Along with the increase of soil moisture content,the yield and NUE increased,while WUE decreased gradually,and the NI had the tendency to increase first and then decrease.Along with the increase of nitrogen input,the yield,NI and WUE had the tendency to increase first and then decrease while the NUE decreased significantly,and the yield,NI,WUE and NUE could not reach the maximum at the same time.Through the study on the grey correlation model of jujube tree’s comprehensive benefit based on the yield,NI,WUE and NUE,results showed the comprehensive benefit of jujube trees was significantly different when W&N input was different,and the gray correlation degree of W2F25 treatment was the highest in two years,which means that the soil moisture content of 50%-75%θand nitrogen input of 0.25 kg/plant was the optimal W&N input for jujube trees under SRI in Northern Shaanxi area.

Technical Studies of Controlling Jujube Witches Broom Disease with Resistant Rootstock

[Objectives]The paper was to screen and identify the control effect of resistant rootstock on jujube witches broom disease.[Methods]The seeds or branches of disease-free plants were collected from wild jujube bushes infected by witches broom disease,and 5434 seedlings were obtained by sowing or cutting.The virus was inoculated by grafting diseased bark.After 6 years of preliminary screening,40 plants with resistance to jujube witches broom disease were obtained.Taking these resistant plants as the rootstocks,the susceptible variety‘long red jujube’was grafted at a height of 40 cm.When the plants grew to appropriate thickness,diseased bark was grafted to‘long red jujube’and rootstock to transmit the virus.After 18 years of observation and judgment,4 rootstock strains with high resistance or immunity to jujube witches broom disease were finally determined,namely 90801,90803,90806 and 908011.The susceptible variety‘long red jujube’was grafted to 4 rootstocks and inoculated the virus through diseased bark grafting method.[Results]The resistant rootstock had obvious disease resistance effect.When the branches of 90801 and 90803 rootstocks were grafted to the trunk of diseased trees,the symptoms of jujube witches broom disease gradually alleviated till disappeared.[Conclusions]Using germplasm with high resistance or immunity to jujube witches broom disease as rootstock can effectively prevent the spread of jujube witches broom disease,and bridging the trunk of diseased trees with branches from resistant rootstock has certain therapeutic effect.