梨幼树部分根域有机肥改良对生长与生理特性的影响
Effects of Partly Root-zone Improved by Organic Fertilizer on Growth and Physiological Characteristics of Young Pear Trees

为确定梨幼树有机肥改良的最佳方法，以2 a生分根盆栽梨幼树为材料，研究1/4、2/4根域用10%、20%、30%有机肥改良对新梢和主干生长、叶片叶绿素SPAD值、净光合速率(Pn)、蒸腾速率(Tr)和气孔导度(Gs)的影响。研究结果表明： 改良1/4根域时，随有机肥水平增加新梢、主干生长与叶片生理特性指标均先增加后减小，20%有机肥处理新梢与主干生长量最大，分别达44.9 cm和1.50 cm；改良2/4根域时，随有机肥水平增加各生长与生理特性指标逐渐降低。10%有机肥水平下，随改良根域增加各生长与生理特性指标增大，而20%、30%有机肥水平下呈现相反的变化趋势。因此，有机肥水平较低、改良根域过少时（1/4根域用10%有机肥），对树体生长与叶片生理特性指标的促进作用有限，而有机肥水平较高或改良根域过多时（1/4根域用30%有机肥，1/4、2/4根域用20%有机肥），新梢和主干生长并不随有机肥水平或改良根域增加而线性提高。综合分析，1/4根域用20%有机肥或2/4根域用10%有机肥对梨幼树根域改良效果最好。
To explore the optimal method of organic fertilizer application for pear trees, two-year-old pear trees were planted in divided pots with 1/4, 2/4 root-zone improved by 10%, 20% and 30% organic fertilizer, and then growth of new shoots and trunk, and leaf characteristics such as leaf chlorophyll SPAD value,net photosynthetic rate (Pn), transpiration rate (Tr) and stomatal conductance (Gs) were investigated.Results indicated that growth of new shoot and Trunk, and leaf Pn, Tr and Gs were increased and then decreased with the organic fertilizer level increasing, and the treatment of 20% organic fertilizer gained the largest grown rate with 44.9 cm for shoots and 1.50 cm for trunk when 1/4 root-zone was improved.However, those were depressed gradually with 2/4 root-zone improved.Treatment of 2/4 root-zone acquired larger growth rate of new shoot and trunk and leaf Pn, Tr and Gs than 1/4 root-zone at the organic fertilizer level of 10%, and it was reversed for treatments of 20% and 30% organic fertilizer.Thus, smaller growth rate of tree and lower leaf physiological characteristics when 1/4 root-zone was improved with 10% organic fertilizer.However, more root-zones improved or higher levels of organic fertilizer application, such as 1/4 root-zone improved by 30% or 1/4, 2/4 root-zone improved by 20% organic fertilizer, might reduce growth rate of trees and trunk and inhibit physiological characteristics.Therefore, considering from growth and leaf physiological characteristics, 1/4 root-zone improved by 20% organic fertilizer or 2/4 root-zone improved by 10% organic fertilizer were the optimal treatments for the young pear trees in this study.