Effects of light and water content in substrate on photosynthetic characteristics in non-heading Chinese cabbage（Brassica campestris ssp.chinensis Makino） | 光照与基质含水量对不结球白菜光合特性的影响

Chinese. 摘　　要：以不结球白菜品种‘绿星’为试验材料,采用3个光照水平（全光照的100%、60%、30%左右）和3个基质含水量水平（基质最大持水量的100%、80%、40%）的复因子试验设计,研究了光照与基质含水量对不结球白菜光合及叶绿素荧光特性的影响。结果表明：降低光照强度和基质含水量显著提高了不结球白菜叶片光合色素含量,但叶绿素a/b以30%光照时最低。在100%光照、80%基质含水量时不结球白菜的净光合速率、蒸腾速率、最大光化学效率、实际光化学效率、表观光电子传递速率和光化学猝灭系数最高,而初始荧光和非光化学猝灭系数最低。说明在100%光照下80%基质含水量有利于降低非辐射能量耗散,将更多的吸收光能用于光化学反应;光照强度较弱情况下（60%光照）,80%基质含水量时不结球白菜光合能力最强;而30%光照时其光合性能显著下降。综上所述,在秋季不结球白菜设施栽培中,100%和60%光照时,80%基质含水量能够有效改善不结球白菜的光合性能,生产中应尽量避免重度遮荫（30%光照）。

English. Using non-heading Chinese cabbage variety ‘Lüxing’ as test material,a multiple factor design（3 levels of light（approximately 100%,60%,30% of full sunlight）and 3 levels of water content in substrate（100%,80%,40% of maximum water content in substrate））were adopted to study the effects of light intensity and water content in substrate on photosynthetic and chlorophyll fluorescence characteristics.The results showed that the contents of pigments in non-heading Chinese cabbage leaves significantly increased with the decrease of light intensity and water content in substrate.Whereas chlorophyll a/chlorophyll b（Chl a/Chl b）values under 30% light were the lowest.Under 100% light and 80% water content in substrate,the values of net photosynthetic rate（Pn）,transpiration rate（Tr）,maximum photochemical efficiency（Fv/Fm）,actual photochemical efficiency（ФPSⅡ）,electron transfer rate（ETR）,and photochemical quenching coefficient（qP）were the highest,whereas initial fluorescence（Fo）and non-photochemical quenching of fluorescence（NPQ）were the lowest,which indicated that the 100% light and 80% water content in substrate could contribute to the decrease of energy dissipation of non-radiation,so more light energy could be allocated to photochemical reaction.The photosynthetic capacity was also promoted when the water content was 80% under weaker light（60%）.Whereas under 30% light,photosynthetic capacity fell significantly.In sum,with 100% and 60% light intensity,80% water content in substrate could improve the photosynthetic characteristics of non-heading Chinese cabbage in protected cultivation in autumn.An extremely low illumination（30% in this experiment）should be avoided in production.