低温胁迫对甜瓜嫁接苗及自根苗光合及叶绿素荧光特性的影响

Effects of low temperature stress on characteristics of photosynthesis and chlorophyll fluorescence in leaves of grafted and own root muskmelon seedlings

以4种白籽南瓜和‘甜宝’甜瓜为嫁接试材,对嫁接苗和自根苗进行15℃/5℃(昼/夜)连续4 d低温处理,测定了4种砧木嫁接苗和自根苗光合与叶绿素荧光特性的变化。结果表明,低温胁迫下嫁接苗和自根苗叶片的净光合速率( P_n)、蒸腾速率(T_r)均逐步降低;除‘甜砧’嫁接苗的气孔导度(G_s)在胁迫4 d略有回升外,其他嫁接苗和自根苗的G_s逐步降低;除‘青研1号’嫁接苗的胞间CO_2浓度(C_i)在胁迫期间无显著变化外,其他嫁接苗的C_i逐步降低,而自根苗的C_i在胁迫1 d略有下降后逐步上升;除‘甜砧’嫁接苗的瞬时水分利用效率(WUE)在胁迫3 d略有回升外,其他嫁接苗和自根苗的WUE均逐步下降。嫁接苗和自根苗叶片的最大荧光(F_m)、最大光化学效率(F_v/F_m)、量子产额(Φ_(PSⅡ))、光化学猝灭系数(q_P)逐步降低,初始荧光(F_o)则逐步上升;除‘青研1号’嫁接苗的非光化学猝灭系数(q_N)在胁迫1 d小幅下降外,其他嫁接苗的q_N逐步上升,而自根苗的q_N在胁迫1 d大幅上升后逐步下降。其中,‘甜砧’嫁接苗胁迫后的 P_n、T_r、G_s、WUE、F_v/F_m、Φ_(PSⅡ)等参数均为最高,可见‘甜砧’嫁接苗光合机构损伤较小,值得在甜瓜耐低温生产中推广应用。

Effects of low temperature stress（15℃/5℃, day/night, for 4 d） on photosynthesis and chlorophyll fluorescence characteristics in leaves of grafted on 4 species of rootstocks and own root muskmelon seedlings were studied. The Pn and Tr gradually decreased under low temperature stress both in the leaves of grafted and own root seedlings; except ‘Tianzhen＇ grafted seedlings increased slightly on the fourth day outside, the Gs of other grafted and own root seedlings gradually decreased; except ‘Qingyan1＇ grafted seedlings was not significantly different outside, the Ci of other grafted seedlings was gradually decreased, while Ci of own root seedlings gradually increased after the first day a slight decrease; except ‘Tianzhen＇ the grafted seedlings increased slightly on the third day outside, the WUE of other grafted and own root seedlings gradually decreased. The Fm, Fv/Fm, Φ（PSⅡ）, qP gradually decreased both in the leaves of grafted and own root seedlings, but Fo was opposite; except ‘Qingyan1＇ grafted seedlings decreased slightly on the first day outside, the qN of other grafted seedlings was gradually increased, while qN of own root seedlings gradually decreased after the first day a big increase. The Pn, Tr, Gs, WUE, Fv/Fm, and Φ（PSⅡ） of leaves of ‘Tianzhen＇ grafted seedlings were highest and it was visible that ‘Tianzhen＇ was worthy of popularization and application in the low temperature production of muskmelon.