一、黄瓜花打顶1、症状“花打顶”在黄瓜苗期或定植初期最易发生。表现为生长点不再向上生长,其附近的节间缩短,形成雌雄间杂的花簇,开花后瓜条不伸长,无商品价值,同时瓜蔓停止生长。2、发生原因(1)干旱。①土壤干旱:营养钵摆靠不紧,水分散失大。苗期水分管理不当,定植后控水蹲苗过度造成。②生理干旱:施肥过量,土壤水分不足,溶液浓度过高,使根系吸收能力减弱造成。(2)夜温低。①温室保温性能差或低温寡照天气,黄瓜白天光合积累物质难以运转,积聚在叶片,使叶浓绿皱缩形成“花打顶”。②白天长期低温也易形成花打顶。(3)伤根。①土温低于10～12℃,土壤相对湿度75%以上,低温过湿造成沤根。②分苗时伤根长期得不到恢复,植株或幼苗营养不良出现花打顶。(4)黄瓜盛果期表现为顶端不长心叶而花包头,不再萌发新叶。主要由于光照不足,灌水不匀,营养 First, cucumber flowers topping 1, Symptoms “Top of flowers ” is most likely to occur in the early stage of cucumber seedling or planting. The performance of the growing point is no longer upward growth, internodes shortened to the vicinity, the formation of mixed flowers between male and female, after flowering is not elongated, no commercial value, while melon to stop growth. 2, causes (1) drought. ① soil drought: nutrient bowl placed tight, large water loss. Improper water management at seedling stage, excessive watering of squat seedlings after planting. ② physiological drought: excessive fertilization, insufficient soil moisture, the solution concentration is too high, so that the weakening of the root absorption capacity. (2) Night temperature is low. ① greenhouse insulation performance is poor or low temperature weather, cucumber daytime photosynthetic accumulation of substances difficult to operate, accumulate in the leaves, so that the leaves thick green shrunk to form “top”. ② long-term low temperature during the day is also easy to form flowers topping. (3) injured roots. ① soil temperature below 10 ~ 12 ℃, the soil relative humidity of 75% or more, low temperature caused by over wet roots. ② sub-seedlings wound root long-term failure to recover, malt plants or seedlings appear topping. (4) Cucumber Sheng fruit period performance is not the top of the heart of the heart and flowers Baotou, no longer germination of new leaves. Mainly due to lack of light, uneven irrigation, nutrition