高温胁迫对黄瓜幼苗N素及C素代谢的影响

高温胁迫 ３ ｄ 后，黄瓜耐热品种津杂 ２ 号幼苗中蛋白质降解速率（４．３６％ ）比不耐热品种中农 １１ 号（８．５１％ ）慢；氨基酸增幅较小，耐热品种为 ２６．３４％ ，不耐热品种为 ３４．７％ ，其中脯氨酸质量分数增幅与品种耐热性呈正相关．耐热品种比不耐热品种具有较高的净光合速率（分别为７．６６、６．６４ μｍ ｏｌ·ｍ － ２·ｓ－ １），较低的呼吸速率（分别为４４５．６６、５６３．４９ μ Ｌ·ｇ－ １ ·ｈ－ １）和乙醇酸氧化酶活性［△ Ｄ（６２０ ｎｍ ）分别为２．０２、２．４２］．解除高温胁迫后，耐热品种的蛋白质合成和净光合速率均较不耐热品种恢复得快，表明耐热品种无论在高温胁迫下或解除胁迫后均比不耐热品种具有较强的平衡 Ｎ、 Ｃ代谢的能力

Effects of high temperature stress on metabolism of nitrogen and carbohydrates in seedlings of cucumber

After 3 days of high temperature stress, the protein degradation rate (4.36%) and the increase of amino acids (26.34%) in seedlings of heat tolerant variety, Jinza No.2, of cucumber were less than those ( 8.51% and 34.7%) of heat sensitive vaviety, Zhongnong No.11, of which there was positive correlation between the increase of proline mass fraction and heat tolerance. Heat tolerant variety had higher Pn (7.66 μmol·m -2 ·s -1 ), lower respiration rate (445.66 μL·g -1 ·h -1 ) and glycolate oxidase activity [△ D (620 nm)=2.02] than heat sensitive one [6.64 μmol·m -2 ·s -1 , 563.49 μL·g -1 ·h -1 and △ D (620 nm)=2.42]. Relieved from high temperature stress, the protein synthesis and net photosynthetic rate (Pn) of heat tolerant variety resumed sooner, which indicated that, whether stressed at high temperature or relieved, heat tolerant variety had stronger ability to balance metabolisms of nitrogen and carbohydrates than heat sensitive one.