甜椒穴盘苗对不同程度水分胁迫-复水的生理生化响应

对温室甜椒穴盘苗进行水分处理,探讨了不同程度水分胁迫-复水过程中叶片生理生化特性的变化.叶片相对含水量(RWC)、渗透势随基质水分减少而降低,渗调能力逐步增强.POD、SOD、CAT酶活性随水分减少而上升,SOD对水分胁迫最敏感,复水后主要由POD、CAT负责清除H2O2和过氧化物.游离氨基酸、脯氨酸随基质水分减少急剧上升,复水后大幅下降,可能为水分胁迫下主要渗透调节物质.水分胁迫下,甜椒叶片可溶性蛋白主要降解为氨基酸的形式参与渗透调节.RWC降至45%(停水后d3)时,可溶性糖显著积累,但明显晚于氨基酸,但它基础含量高,主要在较为严重的水分胁迫时发挥作用.尽管水分胁迫使保护酶活性和渗透调节能力均提高,但任何程度的胁迫均不可避免伤害幼苗.穴盘苗生产中,建议“水分胁迫锻炼”时间以不超过3d逐步达到RWC≥45%为宜.图4表2参12

Physio-biochemical Characters of Sweet Pepper Potting Seedlings Under Different Degree Water Stress and Rewatering

Some physiological and biochemical characters were investigated when sweet pepper seedlings in greenhouse were exposed to different degree water stress and rewatering. The leaf RWC and osmotic potential decreased with decreasing of moisture content, but the osmotic adjustment increased. The activities of POD, SOD and CAT increased with the decreasing of moisture content. SOD was most sensitive to water stress. After rewatering, POD and CAT were mainly responsible for eliminating H_ 2O_ 2 and peroxides. Free amino acid and proline could principally play osmotic role under earlier light stress, and were accumulated sharply under water stress and rapidly reduced after rewatering. Under water stress, soluble protein (based on dry weight) of sweet pepper was gradually decomposed into amino acid and participated in osmotic adjustment. Soluble sugar obviously accumulated until RWC reduced to 45%, which was a little later than amino acid and played the osmotic role in relatively serious stress period . Although water stress could promote protective enzymes activity and osmotic adjustment, any stress would inevitably damage seedlings. As for long-distance transportation and high-quality seedling production, 2~3 days stress hardening was appropriate. Fig 4, Tab 2, Ref 12