春季干旱对金冠苹果不同部位叶片衰老和脱落的影响

春季不同部位叶片发育差异大.而且呈明显规律性.轻度干旱促进各类叶片成熟;严重干旱使长枝基部叶和短枝叶急剧衰老、游离氨基酸积累、内源乙烯大量释放、叶片脱落,但对长枝中部叶的发育影响不大;能促进长枝上部叶的成熟.可见,春季干旱落叶是衰老的结果.春季干旱,对不同部位叶片衰老和脱落的影响与其自身发育的差异有关,因此形成了春季干旱落叶的局部性.

Effect of Water Stress in Spring on Senescence and Abscission of Leaves on Different Position in Golden Delicious Apple Trees

Effect of water stress in spring on senescence and abscission of leaves on the top,mid-dle,basal part of shoot and spur leaf of Golden Delicious apple trees growing in pot was stud-ied.Spring drying induced water stress on all kinds of leaf,but promoted the rapid senes-cence of leaves on the basal part of shoot and on the spur,leading to the decrease of chloro-phyll,soluble protein and the increase of the rate of ethylene production,the accumulation offree amino acids and the abscission.In contrast,the leaves on the top,middle part of shootbecome mature but do not fall down under moderate water strees.The spring drying couldpromote only the mature of top,middle part of stoot.The results suggested that thus,localleaf abscission occur by spring water stress.The effect of spring water stress is closely relat-ed to the leaf position on the limb and shoot.