断根对冬枣营养生长的影响

 以6年生的冬枣(Zizyphus jujuba Mill. ) 为试材, 分别在行间两侧距树干3倍、5倍和7倍胸径距离处对其进行断根处理, 研究了断根对冬枣营养生长的影响。结果表明: 3倍胸径断根与对照相比,枣头一次枝的长度和数量分别减少了27.9%和12.1%。3倍和5倍胸径断根与对照相比, 35 d时叶片N、P、K含量差异不明显, 而断根161 d时差异达显著水平; 叶片光合速率、蒸腾速率、气孔导度、胞间CO₂浓度及根系玉米素( ZT) 含量, 35 d时较对照略有下降, 161 d时则有所升高; 枣头一次枝顶端生长素(IAA) 含量和根系IAA含量, 35 d时较对照略有升高, 而161 d时有所下降; 枣头一次枝顶端乙烯释放量和根系脱落酸(ABA) 含量, 断根35 d和161 d时较对照均有所升高。与3倍胸径相比, 5倍胸径断根对冬枣营养生长的抑制效应有所减弱。冬枣叶片叶绿素含量以3倍胸径含量最高, 随断根距离的增加, 含量逐渐减少, 但一直高于对照。断根促进了果实维生素C和总糖含量增加, 对总酸含量和产量则无明显影响。综合分析认为, 3倍胸径断根是控制营养生长的最佳距离。

Effect of Root Cutting on Vegetative Growth of Zizyphus jujuba Mill.'Dong zao'Trees

The root system of six-year-old Chinese jujube treeswere manually cut with a sharp spade at 3, 5 or 7 times trunk diameter distance along both inter-row sides p rior to buds break on April 26th 2008 in Binzhou Chinese jujube orchards, to study the effects of root cutting on the vegetative growth. The results showed that the root cutting of 3 times trunk diameter decreased the length of once branch by 27.9% and the numbers of once branch by 12.1% in contrast to the control. Compared to the control, root cutting of 3 and 5times trunk diameter had no apparent effects on N, P and K content of leaves after 35 days, but had significant effects after 161 days. Photosynthetic rate (Pn) , transpiration rate (Tr) , stomatal rate (Gs ) , intercellular concentration (Ci ) of leaves and zeatin ( ZT) content of rootwere lowered after 35 days and were raised after 161 days as effected by the root cutting treatments of 3 and 5 times trunk diameter. However, Auxin(IAA) concentrations of once branch top and rootwere increased after 35 days and decreased after 161 days.Also, ethylene release of once branch top and abscisic acid (ABA) content of root were both increased after 35 and 161 days. Compared with root cutting of 3 times trunk diameter, the effect of root cutting on the vegetative growth at the distance of 5 times trunk diameterwasweakened to some extent. Leaf chlorophyll content of Chinese jujube treeswas the highest under the treatment of 3 times trunk diameter root cutting, which declined gradually with the increase of root cutting distance. The contents of vitamin C and total sugar in fruits were increased by root cutting, but no effectswere found on total acid content of fruit and yield at harvest. It is proposed that 3 times trunk diameterwas the best distance for root cutting to regulate the vegetative growth of Chinese jujube trees.