Effect of different dwarfing interstocks on the vegetative growth and nitrogen utilization efficiency of apple trees under low-nitrate and drought stress

Abstract

• Two new interstocks were studied in apple cv. ‘Tianhong 2’. • Apple dwarfing interstocks varied in their responses to nitrate deficiency and drought stress. • ‘SH40’ had the best vegetative growth and N utilization efficiency, followed by ‘J1’ and then ‘J2’. We developed apple plants that are better adapted to growth in high-density orchards in dry areas with low-nutrient soil. One-year-old ‘Fuji’ apple cultivar ‘Tianhong 2’ on ‘ Malus. robusta’ rootstock was cultivated with ‘SH40’, ‘Jizhen 1’, or ‘Jizhen2’ dwarfing rootstock as an interstock bridge to investigate the effects on vegetative growth and nitrogen utilization efficiency under different water and nitrate conditions. The results showed reductions in several growth indices, including plant height, trunk diameter, total dry weight, relative growth rate, chlorophyll content, and net photosynthesis rate, for all interstocks under low-nitrate and drought conditions. The smallest reductions occurred with ‘SH40’ and the highest with ‘Jizhen2’. When subjected to drought, ‘SH40’ showed the minimum and ‘Jizhen2’ the maximum reduction in 15 N accumulation and utilization. Additionally, ‘SH40’ had the highest nitrogen content and uptake flux, regardless of the nitrogen level. These findings suggest that the high tolerance of ‘SH40’ to drought and low-nitrogen stress recommend its use as an interstock.