弱光对春季温室黄瓜生长发育的影响

弱光明显抑制黄瓜的生长发育，主要表现为植株干重降低、茎变细、产量降低、畸形瓜率增高等。弱光导致叶绿素含量下降、净光合速率明显降低。经过弱光处理后的黄瓜幼苗，无论在正常光照下还是在弱光条件下继续生长，其净光合速率均比对照明显降低，而气孔导度和细胞间隙CO2浓度的不同变化说明：在弱光条件下黄瓜幼苗净光合速率的降低是由气孔限制因素造成的；在正常光照下净光合速率的降低可能是由非气孔限制因素造成的。叶绿素荧光动力学测定发现，弱光处理后，黄瓜幼苗和成株的PSⅡ原初光能转化效率(Fv／Fm)没有发生明显变化，不同处理之间差异不显著，说明弱光胁迫并没有使光合作用PSⅡ原初光能转化效率发生实质变化。弱光导致类胡萝卜素含量的下降，可诱发光抑制作用。不同的黄瓜品种对弱光胁迫的反应不同，不同的弱光处理方式对黄瓜生长发育的影响也不相同。多组数据表明，自交系Q21耐弱光能力较强，而T94耐弱光能力较弱，这与多年田间观察的结果一致。对光合作用能量吸收和转换起决定性作用的叶绿素和类胡萝卜素破坏较少，是品种耐弱光的基础。

Effects of Low Light on Growth and Development of Cucumber in Spring Greenhouse

Growth and development of cucumber in spring greenhouse were affected obviously by low light, such as thinness of stem, decreasing dry weight of plants and yield, and increasing abnormal fruit ratio, etc. In low light, the content of Chlorophyll and net photosynthetic rate (Pn) decreased. For the cucumber seedlings that were treated by low light, whether in normal light or low light, its Pn decreased obviously, and the experiment on stomata conductance and intercellular CO2 concentration showed that in the low light the stomata factors resulted in decreasing the Pn of cucumber seedling, while in the normal light the non-stomata factors probably cause the decreasing of Pn. Fv/Fm of cucumber seedlings and plants didn't change obviously after low light treatment. The slight differences in different treatment indicated that Fv/Fm did not cause the qualitative change by low light stress. And low light resulted in decreasing the content of carotenoid and would lead to pho-toinhibition. The reaction of cucumber lines to low light stress was different, and effect of different low light treatment to cucumber growth and development were also not same. Several tests data showed that inbred line Q21 has better resistance than T94 to low light, which accord with the observation in past years. The Chlorophyll and carotenoid that play an important role to the absorption and converting of energy in photosynthetic activity was destroyed slightly and was the foundation of resistance to low light.