Effects of grapes in shelter facilities on tree growth and fruiting of interplanted loquat

Abstract: 【Objective】In order to make full use of the limited space inside the horizontal grape trellis, this study observed and compared the differences in growth and fruiting between interplanted potted loquat trees under the grapes in shelter facilities and the potted loquat trees outside the facilities. The study will provide a reference for the application of“grape-loquat”interplanting model.【Methods】3- year-old loquat Xinbai No. 8 grafted trees with flower buds in the nutrition bag were interplanted with the 5-year-old grape Guipu No. 1 in the shelter facilities. 3-year-old potted loquat Xinbai No. 8 grafted trees with flower buds in the nutrition bags placed in the open air were used as the control. The effects of the ecological environment of the grape shelter facilities on tree growth, shoot growth quality, flowering quality, flowering shoot rate, leaf growth quality, fruit pest and disease incidence, fruit quality and yield per plant were observed for two consecutive years in interplanted potted loquat trees.【Results】 During the growth of the grapes, the shade effect on the loquat trees was highest when the grapes covered the trellis or during the period of growth of loquat summer shoots. The light intensity reduced by 92.37%, the temperature reduced by 6.10 ℃ and the relative humidity increased by 20.87% than that of the control at 12:00 am. During the post-harvest period of grapes or physiological differentiation period of loquat buds, there were a 76.70% decrease in light intensity, a 4.51 ℃ decrease in temperature and a13.56% increase in relative humidity at 12:00 am. compared to the control. The lightest shade effect occurred in the period of grape winter pruning or growth stagnation period of young loquat fruit. The light intensity reduced by 15.90% and the temperature increased by 2.28 ℃ than that of the control at 12:00 am. In the potted loquat trees interplanted under the grapes, the number of shoot growth in the first year was 33.80% and significantly fewer than the control. There were no significant differences in tree crown width, tree height, trunk girth and canopy thickness between shaded loquat trees and the control. The number of shoot growth in the second year was 63.35% fewer than the control, and tree height, trunk girth and canopy thickness of shaded loquat trees were lower than the control by 29.04%, 26.40% and 44.65%, respectively. In the potted loquat trees interplanted under the grapes in shelter facilities, shoot length and leaf number in the first year were 36.30% and 32.33% lower than the control, respectively, with highly significant differences. Shoot thickness and panicle width were 17.91% and 21.86% lower than the control, respectively, with significant differences. Length and thickness of shoot, number of leaves, length and width of flowering spikes and number of flowering terminals in the second year were 57.44%, 29.38%, 49.56%, 47.13%, 50.71% and 42.51% lower than the control, respectively. The leaf length and width of summer shoots were significantly higher than that of the control; leaf length and width of spring shoots were significantly lower than that of the control, and no significant differences in leaf length and width in autumn shoots was found between the interplanted loquat trees and the control. The leaf thicknesses of spring, summer and autumn shoots were significantly smaller than that of the control. In the first year of the trial, due to the high rainfall during the fruit growing season, the rates of fruit cracking, anthracnose fruit and sunburn fruit for the interplanted potted loquat trees under grape shelter facilities were lower than that of the control by 16.65%, 26.20% and 7.93%, respectively. The rate of good fruit was 27.25% higher than that of the control. In the second year, the rate of fruit drop under the trellis was lower than that of the control by 14.03%. The rates of anthracnose, wrinkled, insect, and sunburn fruit were lower than that of the control by 14.28%, 3.88%, 3.04% and 3.73%, respectively. The rate of good fruit was higher than that of the control by 12.89%. In the first year of the trial, with no flower and fruit thinning, the spike weight and yield per plant of loquat trees in the trellis were 62.72% and 69.63% of those in the control, respectively. After flower and fruit thinning in the second year, the differences in cob weight, fruit mass, flesh thickness, soluble solids and flesh recovery of fruit from loquat trees in the trellis were insignificant compared to from the control trees; yield per plant was 69.67% of the control.【Conclusion】The loquat trees interplanted under the grapes in shelter facilities can grow and bear fruit normally, with lower incidence of fruit diseases and pests. It is a feasible model for interplant, but further research is needed on suitable supporting cultivation techniques to reduce the shading effect on the growth of interplanted loquat trees.