Effects Of Combined Application Of Boron Fertilizer And Water Retaining Agent On Growth And Yield Of Beet In Leaf Cluster Stage Under Drip Irrigation

Objective:Xinjiang is one of the dominant sugar beet producing regions in China.In recent years,Xinjiang has made full use of its resources and geographical advantages,and the total sugar beet production has continued to increase,but the sugar content has gradually decreased,becoming an obstacle factor limiting the development of the sugar beet industry in this region.Sugar beet is a boron sensitive crop.Spraying boron fertilizer on the leaf is beneficial to improve the yield and sugar content of sugar beet root.Whether the drip irrigation water fertilizer integration technology can be used to apply boron fertilizer while improving the utilization rate and sugar content of boron fertilizer is of great significance for guiding the quality and efficiency improvement of drip irrigation sugar beet cultivation in Xinjiang.Methods:The experiment adopted a split split zone design,with boron application as the main zone,water retaining agent as the split zone,and the variety as the split zone.Four boron application treatments were set up,namely 0 kg·hm^-2（M0）,1.2 kg·hm^-2（M1）,2.4 kg·hm^-2（M2）,and 4.8 kg·hm^-2（M3）;Two water retaining agent treatments,namely 0 kg·hm^-2（Z0）,75 kg·hm^-2（Z1）,and two tested varieties,namely high-yield sugar beet variety Beta 796（V1）and standard sugar beet variety ST 13092（V2）,were used to study the effects of each treatment on boron utilization efficiency,growth,and yield of drip irrigation sugar beets.Results:（1）The boron content in various organs of sugarbeet plants showed as follows:leaf>petiole>root tuber.Under different boron application rates,the boron content in leaves(30.65 mg·kg^-1),petioles(15.27 mg·kg^-1),root tubers(11.07 mg·kg^-1),soil total boron content(86.93 mg·kg^-1),and boron fertilizer utilization efficiency（59.05%）of sugar beet reached the maximum under M2 treatment.Compared with the treatment without water retaining agent,the utilization rate of boron increased by 5.55%-26.67%after applying water retaining agent.The boron utilization efficiency of the intercropping plants of the two varieties was Beta 796>ST 13092.（2）Under different boron application rates,M2 treatment significantly increased the chlorophyll content,gas exchange parameters,and fluorescence parameters of sugarbeet leaves at the leaf cluster stage.Compared with the treatment without water retaining agent,the net photosynthetic rate Pn of sugarbeet leaves at the leaf cluster stage was significantly increased by 16.52%-17.34%,and the intercellular carbon dioxide concentration Ci was significantly increased by 27.26%-31.31%.Beta 796 has higher chlorophyll content,gas exchange parameters and fluorescence parameters than ST 13092.（3）The content of soluble total sugar in various organs of sugarbeet plant was as follows:root tuber>leaf>petiole.Under different boron application rates,M2 treatment significantly increased the total soluble sugar content（1.6%-5.8%,7.7%-23.2%,and 5.2%-21.9%）,sucrose content（4.3%-11.7%,12%-40.4%,and 7.4%-38.6%）,fructose content（10.5%-43.2%,9%-40.7%,and 22.2%-46.7%）,and glucose content（8.8%-24.2%,6.9%-20.3%,and 11.9%-36.7%）in root tubers,petioles,and leaves of sugarbeet at the leafy stage.The application of water-retaining agent significantly increased the sucrose content in sugar beet petiole and fructose content in root tuber.The content of soluble total sugar and glucose in root tubers,sucrose in petioles,and fructose in root tubers and leaves among the two varieties were all Beta 796>ST 13092.（4）M2 treatment significantly increased the dry matter accumulation of sugar beet under different boron application rates.Compared with the treatment without applying boron fertilizer,the yield,sugar content,and sugar yield of sugar beet under M2 treatment were significantly increased by 8.7%,8.5%,and17.7%.The application of water retaining agent significantly increased the dry matter accumulation of sugar beet,but had no significant impact on the yield,sugar content,and sugar yield of sugar beet.Compared with ST 13092,the sugar content of Beta 796 was significantly increased by 6.8%,but the yield and sugar yield of the two varieties were not significantly different.Conclusion:Combined application of boron fertilizer(2.4 kg·hm^-2)and water retaining agent(75kg·hm^-2)at the leaf cluster stage can improve the utilization rate of boron fertilizer,increase dry matter accumulation,yield,and sugar content of sugar beet under drip irrigation in arid areas,which has a more significant effect in high-yield sugar beet varieties.