气温和湿度对华盛顿脐橙生理落果的影响

THE EFFECTS OF AIR TEMPERATURE AND HUMIDITY ON JUNE DROP OF WASHINGTON NAVEL ORANGE

当5月平均最高气温达29℃、极端最高温41℃时,华盛顿脐橙生理落果率增加8.3～19.1%,产量减少55～61%。产量与温度呈显著负相关(r=-0.89~#)。人工气候箱模拟表明,在极端高温为36℃、38℃和41℃情况下,90%相对湿度比75%的落果率分别高出16.6%,2.9%和2.3%。高温对光合作用抑制强烈,在40℃时净光合强度降低79%,45℃时降低85%,导致植株碳素营养不足而落果。

An investigation of washington orange navel trees in Fengjie country,Sichuan province showed that when the monthly mean maximum temper-ature reached 29℃ and the extreme temperature reached 41℃ in May,physiological fruit drop increased by 8.3-19.9%,with a subsequent yielddecline of up to 55-61%.A significant negative correlation(r=-0.89~*)was observed between the temperature in May and fruit yield.A simula-tion study in a phytoton showed that fruit drop rate was 16.6,2.9 and 1.3%higher at 75% RH than at 90% RH at 36,38 and 41℃,respectively.Thedeficiency of carbohydrate nutrients resulting from inhibition of photosyn-thesis at high temperatures caused severe fruit drop.