木棉对不同浇水频率及持续干旱的生理响应

Effects of Different Watering Frequencies and Continuous Drought on Physiological Characteristics of Bombax ceiba

通过研究浇水频率对木棉幼苗生理生化特性的影响及外源氯化钙(CaCl_2)和水杨酸(SA)处理对其抗旱性的影响的结果表明:不同浇水频率间(2天浇1次,4天浇1次,6天浇1次)木棉的叶绿素相对含量、气孔导度和光系统Ⅱ最大光化学效率(Fv/Fm)无显著差异。在处理第6天时,过氧化物酶(POD)和超氧化物歧化酶(SOD)的活性在2天浇1次和4天浇1次的处理中显著高于6天浇1次的处理,但到处理第60天时,各处理间的差异不再显著。可见,以上3种浇水频率对木棉的生理生化影响差异较小。停止浇水持续干旱7天时,10 mg/L SA处理的叶绿素相对含量显著高于对照;干旱14天时,10 mg/L CaCl_2,40 mg/L CaCl_2和10 mg/L SA处理的Fv/Fm显著高于对照;干旱21天时,10 mg/L CaCl_2处理的Fv/Fm显著高于对照。可见,10 mg/L和40 mg/L CaCl_2及低浓度(10 mg/L)的SA在干旱程度较轻时都可以提高木棉的抗旱性,但是在干旱程度较重时,10 mg/L CaCl_2提高木棉抗旱性的效果最好。

Bombax ceiba is a deciduous tree that can grow in the dry-hot valley of southwestern China.Tounderstand the adaptation of this species to drought,the effect of watering frequencies on physiological andbiochemical characteristics and effect of exogenous application of calcium chloride(CaCl2)and salicylicacid(SA)on drought tolerance of B.ceiba were studied.The results showed:1)There was no significantdifference of relative chlorophyll content,leaf stomatal conductance and maximum quantum yield ofphotosystem II(Fv/Fm)among different watering frequencies(every2,4,6days respectively for1timewatering).On the6th day of treatment,the activity of peroxidase(POD)and superoxide dismutase(SOD)oftreatments of every2and4days for1time watering were significant higher than that of treatment of every6days for1time watering.However,on the60th days,they did not differ significantly among different wateringfrequencies.It can be concluded that there were little variation in the effect of3watering frequenciesmentioned above on physiological and biochemical characteristics of B.ceiba.2)Watering was stopped to conduct drought treatment.The relative chlorophyll content of seedlings pretreated with10mg/L SA wassignificantly higher after7d of drought,Fv/Fm of seedlings pretreated with10mg/L CaCl2,40mg/L CaCl2and10mg/L SA were significantly higher after14d of drought,and Fv/Fm of seedlings pretreated with10mg/L CaCl2was significantly higher after21d of drought,compared to the control.It can be concluded that10,40mg/L CaCl2and and low concentration of SA(10mg/L)were conducive to improve the droughttolerance of B.ceiba under slight drought.However,only10mg/L CaCl2can improve the drought toleranceof this species under severe drought.