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为了探明外源水杨酸(SA)和2,4-表油菜素内酯(EBR)对低温胁迫下黄瓜幼苗光合作用的调控机理,以‘优博1-5’黄瓜为试材,用1 mmol·L~(-1)SA和0.1μmol·L~(-1)EBR喷施预处理幼苗,每天喷1次,连喷2 d后置于低温下[10℃/5℃,光强(PFD)80μmol·m~(-2)·s~(-1)]处理.结果表明:低温胁迫下黄瓜幼苗生长量及净光合速率(P_n)下降;喷施SA和BER显著提高了P_n、光系统Ⅱ最大光化学效率(F_v/F_m)、光系统Ⅱ实际光化学效率(Φ_(PSⅡ))和光化学猝灭系数(q_P),减缓了非光化学猝灭系数(NPQ)增加的幅度,同时核酮糖-1,5-二磷酸羧化/加氧酶(Rubisco)、景天庚酮糖-1,7-二磷酸酯酶(SBPase)、转酮醇酶(TK)和果糖-1,6-二磷酸醛缩酶(FBA)活性明显升高.说明SA和EBR可以通过调节光合关键酶的活性,缓解低温对黄瓜幼苗光合作用的影响,增强其对低温的适应性.
In order to investigate the regulatory mechanism of exogenous salicylic acid (SA) and 2,4-epibrassinolide (EBR) on photosynthesis of cucumber seedlings under low temperature stress, Seedlings were pretreated with 1 mmol·L -1 SA and 0.1 μmol·L -1 EBR, and sprayed once a day for 2 days, then placed in low temperature [10 ° C / 5 ° C, light intensity (PFD) 80μmol · m -2 · s -1] .The results showed that the growth and the net photosynthetic rate (P_n) of cucumber seedlings decreased under low temperature stress.The SA and BER significantly increased the P_n, The maximum photochemical efficiency (F_v / F_m) of photosystem Ⅱ, the actual photochemical efficiency (Φ_ (PSⅡ)) and the photochemical quenching coefficient (q_P) of photosystemⅡ slowed down the increase of non-photochemical quenching coefficient (NPQ) Rubisco, Sedum heptulose-1,7-diphosphatase (SBPase), Transketolase (TK), and fructose- 1, 6- The results showed that SA and EBR could alleviate the effect of low temperature on the photosynthesis of cucumber seedlings and enhance their adaptability to low temperature by regulating the activity of key enzymes of photosynthesis.