弱光对两品种黄瓜光合特性和生长发育的影响

以华北型黄瓜中农8号和西南本地春秋黄瓜为试材,秋露地栽培,通过遮光模拟弱光逆境,幼苗定植大田缓苗后,用单层黑色遮阳网(遮荫率70%)遮荫直至拉秧,生育期内测定弱光逆境下黄瓜植株主要生长发育指标和基本光合参数。结果表明,遮光处理后两品种黄瓜株高升高,茎蔓变细,叶数减少,叶片变薄,株叶面积增大,根冠比增大,整株鲜、干样质量减少,向叶分配比例降低,向根、茎分配比例升高,尤以茎的明显。叶绿素a、b、类胡萝素含量上升。净光合速率、气孔导度、蒸腾速率、水分利用效率、气孔限制值降低,而胞间CO2浓度升高。根瓜节位升高,单株结瓜数减少,化瓜数增多,单株产量下降。弱光下虽春秋黄瓜的株高、株叶面积、整株鲜样质量、光合色素含量、净光合速率等值高于中农8号,但前者前15节雌花数、单株结瓜数、单瓜鲜重等值低于后者,即使春秋黄瓜植株具有较强的光合能力,但其雌花数、结瓜数少,终使产量不及中农8号。由此可知,春秋黄瓜的弱光耐受性差于中农8号。

Effect of low light on photosynthesis characteristics, growth and development of two cucumber cultivars

Take two cucumber cultivars of Zhongnong8 belonging to North-China-type and Chunqiu belonging to local cultivar in Southwest region as materials in this trial,which were planted in the open field in autumn in Guiyang City.The low-light-stress environment was imitated by shading.The field treatment plots were covered by a monolayer black sunshade net after cucumber seedlings regrown after transplanting until adult plants uprooted after harvested.Some chief growth and development indices and fundamental photosynthetic parameters were measured in growth period under low light environment.The results indicated that higher plant height,slender stem,less leaf number,thinner leaf,larger plant leaf area,higher root shoot ratio,less plant fresh mass or dry mass,lower matter partitioning proportion for leaf and higher matter partitioning proportion for root and stem(especially for stem) were observed in the two cultivars after shading in this investigation.Simultaneously,the values of chlorophyll a,chlorophyll b and carotenoid content increased and the ones of net photosynthetic rate,stomatal conductance,transpiration rate,water use efficiency and stomatal limitation value were decreased and accompanied by the one of intercellular CO2 concentration increased.Higher the node location of 1st cucumber fruit,poorer fruit-setting per plant,lower yield per plant were also observed in the treatment plots.Even though the values of plant height,plant leaf area,plant fresh mass,photosynthetic pigments content and net photosynthetic rate etc.in Chunqiu were higher than the ones in Zhongnong8,the values of the female flower number of former 15 nodes,fruit-setting number per plant and fresh mass per fruit in former were lower than the ones in latter.The yield of Chunqiu was lower than the one of Zhongnong8,because of less female flower number and fruit-setting number in Chunqiu,even its photosynthetic capacity was stronger than that in Zhongnong8.Those indicated comprehensively that the low light tolerance in Chunqiu was weaker than that in Zhongnong8.