扁桃品种耐旱性评价及干旱胁迫下茎木质部自然栓塞度和解剖结构的比较

Drought tolerance evaluation of almond cultivars and comparison on stem xylem natural embolism degree and anatomical structure under drought stress

以厚壳甜扁桃品种‘大巴旦’(A.communis var.typica‘Dabadan’)、厚壳甜扁桃品种‘石头巴旦’(A.communis var.typica‘Shitoubadan’)、软壳甜仁扁桃品种‘公巴旦’(A.communis var.sativa‘Gongbadan’)和苦扁桃品种‘苦巴旦’(A.communis var.amara‘Kubadan’)(分别简称‘大巴旦’、‘石头巴旦’、‘公巴旦’和‘苦巴旦’)的2年生实生苗为研究材料,比较干旱胁迫(土壤含水量保持在田间最大持水量的20%~40%)35 d 4个扁桃品种的叶片解剖结构和相对含水量,在此基础上,采用隶属函数法评价各扁桃品种的耐旱性,并比较干旱胁迫35 d 4个扁桃品种茎木质部的自然栓塞度和解剖结构。结果表明:干旱胁迫下,多数叶片解剖结构指标和相对含水量在不同扁桃品种间差异不显著;‘公巴旦’茎木质部的自然栓塞度、导管平均面积和连接导管壁厚度显著(p<0.05)高于另3个扁桃品种,剩余茎木质部解剖结构指标在多数扁桃品种间差异不显著。与对照(土壤含水量保持在田间最大持水量的75%~80%)相比,干旱胁迫下‘公巴旦’的叶片厚度、上表皮角质层厚度、下表皮细胞厚度、侧脉维管束占比、叶肉细胞紧实度和叶片相对含水量显著下降,但叶肉细胞孔隙度显著升高;而干旱胁迫下另3个扁桃品种多数叶片解剖结构指标与对照的差异不显著。干旱胁迫下4个扁桃品种茎木质部解剖结构指标与对照的差异不显著,茎木质部自然栓塞度却显著高于对照,其中,‘公巴旦’茎木质部自然栓塞度的增幅最高(208.28%)。前4个主成分的累计贡献率为81.938%,4个主成分中载荷量绝对值最高的指标分别为叶肉细胞紧实度、上表皮角质层厚度、下表皮角质层厚度、叶片相对含水量。基于上述4个指标,‘大巴旦’、‘石头巴旦’、‘公巴旦’和‘苦巴旦’的平均隶属函数值分别为0.5448、0.5238、0.5119和0.4642。综上所述,4个扁桃品种均有一定的耐旱能力,其中,‘大巴旦’的耐旱性最强,‘苦巴旦’的耐旱性最弱;‘公巴旦’茎木质部对干旱胁迫最敏感,在干旱胁迫环境中容易发生栓塞。

Taking two-year-old seedlings of Amygdalus communis var.typica‘Dabadan’,A.communis var.typica‘Shitoubadan’,A.communis var.sativa‘Gongbadan’,and A.communis var.amara‘Kubadan’(‘Dabadan’,‘Shitoubadan’,‘Gongbadan’,and‘Kubadan’for short,respectively)as research materials,the leaf anatomical structures and relative moisture content of four almond cultivars under drought stress(soil moisture content maintained at 20%-40%of the maximum moisture content in field)for 35 d were compared,on the basis,the drought tolerance of each almond cultivar was evaluated by using subordinate function method,and the natural embolism degree and anatomical structures of stem xylem of four almond cultivars under drought stress for 35 d were compared.The results show that under drought stress,the differences in most leaf anatomical structure indexes and relative moisture content among different almond cultivars are not significant;the natural embolism degree,mean vessel area,and intervessel wall thickness of stem xylem of‘Gongbadan’are significantly(p<0.05)higher than those of the other three almond cultivars,while the rest stem xylem anatomical structure indexes are not significantly different among most almond cultivars.Compared with the control(soil moisture content maintained at 75%-80%of the maximum moisture content in field),leaf thickness,upper epidermis cuticle thickness,lower epidermis cell thickness,proportion of vascular bundle of lateral vein,mesophyll cell tightness,and relative moisture content in leaf of‘Gongbadan’under drought stress decrease significantly,but its mesophyll cell porosity increases significantly;while the differences in most leaf anatomical structure indexes of the other three almond cultivars under drought stress are not significant with those of the control.There is no significant difference in stem xylem anatomical structure indexes of four almond cultivars between drought stress and the control,but the natural embolism degree of stem xylem is significantly higher than that of the control,in which,the increment of natural embolism degree of stem xylem of‘Gongbadan’is the highest(208.28%).The cumulative contribution rate of the first four principal components is 81.938%,and indexes with the highest absolute values of load of four principal components are mesophyll cell tightness,upper epidermis cuticle thickness,lower epidermis cuticle thickness,and relative moisture content in leaf,respectively.Based on the four above-mentioned indexes,the mean subordinate function values of‘Dabadan’,‘Shitoubadan’,‘Gongbadan’,and‘Kubadan’are 0.5448,0.5238,0.5119,and 0.4642,respectively.Taken together,the four almond cultivars all have some drought tolerance,in which,the drought tolerance of‘Dabadan’is the strongest,and that of‘Kubadan’is the weakest;the stem xylem of‘Gongbadan’is most sensitive to drought stress,and it is easy to occur embolism under drought stress environment.