论文部分内容阅读
连续3个夏季在南京测试了不同覆盖方式和规格型号的遮阳网性能及其对夏白菜产量与品质的影响,结果表明:不同类型遮阳网的遮光率、透射光质、照度均不同。蒸散量减少率与遮光率基本同步。降温效应主要表现为地面最高温度,地上至地下各20cm范围和叶温均显著降低。在夏季最高气温超过35℃的晴热型气候下,地面最高气温上限达56.2C,下限41C,覆盖后平均降温9～13℃,最大降幅达19.9℃,夏白菜覆盖增产63％～435％(1992年);最高气温在30～35℃时,地面最高温度变幅为33.7～44.5℃。在冷夏多阴雨的1991和1993年,黑网覆盖的均减产,仅45％～50％遮光率的灰网大棚覆盖的增产;最高气温在25～30℃时,覆盖降温效应很弱。覆盖栽培的夏白菜外观商品性优于露地产品,但内涵营养品质均下降,硝酸盐积累量上升。如在采收前5天揭网处理,各项营养品质指标均赶上或超过露地的,硝酸盐含量也低于露地产品,故采前揭网是必不可少的栽培措施。
The results showed that the shading rate, transmission light quality and illuminance of different types of shading net were different in different shading patterns. Evapotranspiration reduction rate and the basic rate of shading synchronization. The cooling effect is mainly manifested as the highest ground temperature, the range of 20 cm above ground to the ground and the leaf temperature were significantly reduced. In the clear-heat climate with summer maximum temperature above 35 ℃, the maximum upper ground temperature reached 56.2C and the lower limit reached 41C, the average temperature dropped 9 ~ 13 ℃, the maximum decrease 19.9 ℃ and the summer cabbage coverage 63 ~ 435% 1992); the highest temperature in the 30 ~ 35 ℃, the maximum ground temperature range of 33.7 ~ 44.5 ℃. In the cold summer and rainy 1991 and 1993, black net coverage are reduced production, only 45% to 50% shading rate covered by gray net greenhouses increase; maximum temperature 25 ~ 30 ℃, the coverage of the cooling effect is very weak. The covered cultivated summer cabbage had better appearance and commerciality than the open-field products, but the connotation of nutritional quality decreased and the nitrate accumulation increased. If the net 5 days before harvesting net treatment, the nutritional quality indicators are to catch up with or exceed the open field, nitrate content is also lower than the open-air products, so pre mining network is an essential cultivation measures.