Investigations of root function in fruit trees and application of suitable root conditions

1.研究了水分胁迫对荔枝和桃树幼树叶片和根部山梨醇产生的影响，以及叶片和根部细胞核的解剖变化和细胞内淀粉的积累。水分胁迫增加了荔枝叶片、根部和桃树叶片中山梨醇的含量。水分胁迫恢复后，山梨醇在根和叶片中的含量逐渐降低。对照树上长出了新的根。水分胁迫导致核降解加速，叶肉组织和根尖淀粉积累减少。2.研究了果树初生白根初生木质部分化与根径差异的关系。蜜橘的木质部数目为4-6个，梨为3-7个，葡萄为3-6个，荔枝为4-8个，石榴为5-7个，杨梅为3-7个。梨和葡萄的根部木质部脊数随着根径的增加而增加。桃根的木质部脊数为3~7个。这些结果表明，与不施氮的植株相比，施氮的植株中含有许多初生木质部细胞的粗根数量增加得更多。3.蔷薇科果树在靠近内胚层的几层皮质组织中观察到细胞壁向内生长(phi-加厚)，这是一种不寻常的次生细胞壁增厚，并在内胚层内发育出凯氏带。在Casparian条带形成之前，PHI增厚作用已相当发育。当在干旱胁迫条件下种植的树的根被取样时，观察到比正常条件下显著地发展了phi增厚。干旱条件下，根系皮层phi增厚可能是其抵御水分胁迫的一种机制。

1.The effects of water stress on the production of sorbitol in the leaves and roots of young loquat and peach trees, as well as anatomical changes to nuclei and starch accumulation in the cells of leaves and roots were investigated. Water stress increased the sorbitol content in the leaves and roots of loquat trees and in the leaves of peach trees. After recovery from water stress, the sorbitol content decreased gradually in roots and leaves. New roots developed in control loquat trees. Water stress resulted in an acceleration of nuclear degradation and a decrease in starch accumulation in the mesophyll parenchyma and in the root tip.2.Primary xylem differentiation in new white roots was examined relative to the difference in root diameter in fruit trees. The number of xylem was 4-6 in trifoliate orange, 3-7 in pear, 3-6 in grape, 4-8 in loquat, 5-7 in pomegranate, and 3-7 in myrica. The number of xylem ridges of the root in pear and grape was generally found to increase with root diameter. The number of xylem ridges ranged from 3-7 in peach roots. These results indicate that the numbers of thick roots having many primary xylem cells increased more in nitrogen fertilized plants than did those in no-nitrogen ones.3.Cell wall ingrowth (phi-thickening), an unusual secondary cell wall thickening, in several layers of cortical tissue adjacent to the endodermis and the development of the Casparian strip within the endodermis were observed in Rosaceae fruit trees. Phi-thickening developed considerably before the completion of Casparian strip. When roots were sampled from trees planted under drought stress conditions in loquat roots, phi-thickening was observed to have developed dramatically compared to normal conditions. The development of phi thickenings of cortex in loquat roots under drought conditions may be regarded as a defense mechanism from water stress.