旱坡地枣树的萎蔫现象

枣树的萎蔫现象是指果实的萎蔫和叶片的萎蔫。果实萎蔫是指在持续高温干旱、土壤水分不足的情况下，果实水分蒸腾量大于吸收量而产生的失水变软，果面表皮皱缩现象，分为暂是萎蔫和永久萎蔫。暂时萎蔫一般从当天14：00开始至18：00结束。果实萎蔫时期一般是在气温较高的7－8月份，以7月下旬至8月上旬最为严重，特殊年份可持续至9月上旬。干旱年份萎蔫果百分率高达16％－28％，密植园枣树密度较大者，果实萎蔫百分率较大，可上升到385。黄土区集水枣园果实开始萎蔫时的土壤水分含量在6％左右。果实萎蔫期正值果实的重要经济性状形成期，如果肥水缺乏，就会影响果肉细胞膨大，导致果个变小，品质下降，应当引起界的高度重视。枣树幼树叶片的永久萎蔫系数为3．5％，而枣大树叶片的永久萎蔫系数应在3％左右。

The Wilting Phenomenon of Jujube in Arid Hillside Fields

The wilting phenomenon of jujube just pointed to the fruit wilting and the leaf blade wilting. The fruit wilting was the fruit wall's crumpling phenomenon when the fruit skins lose water and became soft under the conditions of continued high temperature, drought, and soil water insufficiency, which can be divided into the temporal wilting and the permanent wilting. The temporal wilting began at 2 p.m. and ended at 6 p.m. during the day. The fruit wilting period in the year was commonly in the highest air temperature months of July and August, the severity of which occurred from the last ten-day period of July to the first ten-day period of August. The fruit wilting can last to the first ten-day period of September in the special year. The percentage of fruit wilting in the arid year can reach 16 percent to 28 percent, and the percentage of fruit wilting in higher density one in the close planting gardens was higher which can reach 38 percent. The soil water content when fruit began wilting in water-collecting garden in loess hills area was about 6 percent. The period of fruit wilting is just the one in which fruit important properties form, if water and fertilizer lack, the expanding of pulp can be affected so that the fruit gets small and quality declines, on which stress should be laid by the cultivating world. The permanent wilting coefficient of young jujube trees was 3.5 percent, but that of elder trees was about 3 percent.