不同光照强度补光对模拟贮运三角梅叶片脱落的缓解效应

以3年生‘大红’三角梅为材料进行为期一个月的模拟贮运,期间采用荧光灯(管径16 mm、28W、光照强度9.45μmol·m-2·s-1)处理,设置黑暗(T0,无灯管)和光照强度低(T1,1个灯管)、中(T2,2个灯管)、高(T3,3个灯管)4个补光(8 h·d-1)处理,考察各处理植株落叶率以及叶片光合色素含量、细胞膜透性、抗氧化酶活性等相关生理生化指标,探讨补光对贮运期三角梅叶片脱落的影响,为解决三角梅贮运过程严重落叶问题提供依据。结果表明:(1)模拟贮运第28天,T0和T3处理三角梅植株落叶严重,落叶率达87%以上,T1和T2处理落叶率则显著低于T0和T3处理,仅分别为16.33%和16.92%;T1~T3处理叶片比叶重均高于T0处理,叶片相对含水量则低于T0处理。(2)T1和T2处理叶片的相对电导率、丙二醛(MDA)含量、可溶性蛋白质含量均显著低于T0处理。(3)T0、T2、T3处理的叶片叶绿素a、叶绿素b、叶绿素总量和类胡萝卜素含量均呈先升后降趋势,而T1处理总体呈上升趋势,变化幅度较小。(4)整个贮运期内,各处理三角梅叶片超氧化物歧化酶(SOD)活性均呈逐渐上升趋势,过氧化氢酶(CAT)活性和过氧化物酶(POD)活性则均呈先升后降的趋势,CAT活性在T0、T1和T2处理间差异不显著,POD活性表现为T1和T2处理显著高于T0;第28天,T2处理叶片SOD活性显著高于T1,两者分别比第0天上升60.86%和45.02%。研究发现,每天采用一根荧光灯(光照强度9.45μmol·m-2·s-1)对三角梅进行每天补光8 h,能够较大程度减轻贮运过程中黑暗胁迫对叶片细胞膜造成的损伤和光合色素含量的影响,降低光合产物消耗和叶片黄化脱落,使其在贮运过程中维持正常生长,减少经济损失。

Mitigative Effects of Supplementary Light Intensity on the Leaves Shedding of Bougainvillea spectabilis during Storage and Transportation

With the fluorescent lamp(16 mm diameter,28W,light intensity 9.45μmol·m-2·s-1)as light source to set up four supplementary treatments,including dark(T0,without lamp)and low(T1,one lamp),medium(T2,two lamp)and high(T3,three lamp)light intensities(8 h·d-1),we simulated a one-month of storage of Bougainvillea spectabilis‘Crimsonlake’,and measured the defoliation rate,photosynthetic pigment content,cell membrane permeability,antioxidant enzyme activity and other related physiological and biochemical indexes of leaves,so as to study the effect of supplementary treatments on the leaves of B.spectabilis and provide the basis for solving the serious defoliation problem during storage and transportation of B.spectabilis.The results showed that:(1)on the 28th day of simulated storage,the defoliation rates of T0 and T3 treatments were serious,reaching over 87%,and the defoliation rates of T1 and T2 treatments were significantly lower than that of T0 and T3 treatments,only 16.33%and 16.92%;The specific leaf weight of T1~T3 treatments is higher than that of T0 treatments,and the relative water content is lower than that of T0 treatments.(2)The relative conductivity,MDA content,soluble protein content of T1 and T2 treatments were significantly lower than that of T0 treatment.(3)The contents of chlorophyll a,chlorophyll b,total chlorophyll and carotenoid in leaves of T0,T2 and T3 treatments increased firstly and then decreased,while that of T1 treatment showed an upward trend with small changes.(4)During the whole storage and transportation period,the activity of superoxide dismutase(SOD)in the leaves showed a gradual increase,while the activities of catalase(CAT)and peroxidase(POD)increased firstly and then decreased.There was no significant difference in the CAT activity of leaves between T0,T1 and T2 treatments.POD activity of leaves treated with T1 and T2 was significantly higher than that of T0 treatment.On the 28th day,the SOD activity in the leaves of T2 treatment was significantly higher than that of T1 treatment,which increased by 60.86%and 45.02%,respectively,compared with the 0th day.The research indicated that the light intensity of 9.45μmol·m-2·s-1,i.e.a fluorescent lamp,could be used to compensate light for 8 h·d-1 on the B.spectabilis during storage,which could reduce damages of the cell membrane and influences of the photosynthetic pigment caused by the dark stress in the process of storage.It was beneficial to reduce the wastage of photosynthetic product in the leaves and the yellowing of the leaves,so that the B.spectabilis could grow normally during storage to reduce economic losses.