增施钙对镉胁迫下大蒜生理特性及品质的影响

Effects of Exogenous Calcium on Physiological Characteristics and Qualities of Garlic Under Cadmium Stress

通过营养液水培方式,探究了镉(Cd2+)对大蒜生长、光合特性、主要矿质元素吸收及品质的影响,同时研究了增施不同浓度钙(Ca2+)对镉胁迫大蒜的缓解效应。结果表明:镉胁迫处理可明显减小大蒜植株的形态指标(株高、假茎粗、假茎长、鲜质量和干质量),降低叶片色素含量、净光合速率(Pn)、蒸腾速率(Tr)及气孔导度(Gs),减少根中矿质元素(N、P、K、Ca、Mg)含量并增加镉积累,降低蒜薹和鳞茎(蒜头)的外观品质(鲜质量、蒜薹直径、抽薹率和鳞茎横径)及营养品质(大蒜素、可溶性糖、维生素C、游离氨基酸和可溶性蛋白)。增施钙可有效缓解镉对大蒜生长的抑制,随所增施钙浓度的提高,大蒜植株的形态指标均呈现先升后降的趋势,最大增幅分别为54.4%、26.0%、45.2%、61.4%和77.3%;同时,增施钙能显著提高镉胁迫大蒜叶片的色素含量及光合参数(Pn、Tr、Gs),其变化趋势与形态指标相似,最大提高量分别为44.6%、36.6%、31.8%和18.4%;另外,增施适量钙增加了镉胁迫大蒜根中矿质元素含量并减少了镉积累,有效提高了蒜薹和鳞茎的外观、营养品质。

In this experiment,the effect of cadmium(Cd2+)on growth,photosynthetic characteristics,absorption of main mineral elements,and qualities of garlic were studied,as well as the alleviation effect of exogenous Ca2+. The results showed that Cd obviously inhibited the growth of garlic seedlings,reduced pigment contents and photosynthetic parameters(Pn,Tr,Gs)of leaves,decreased mineral elements(N,P,K,Ca,Mg)contents and increased Cd accumulation of roots,and lowered qualities of garlic bolts and bulbs. The growth was promoted significantly after adding exogenous Ca to garlic seedlings under Cd stress,the morphological indexes(plant height,pseudostem diameter,pseudostem length,plant fresh weight,plant dry matter)increased at first and then decreased with the increase of exogenous Ca concentrations,the biggest increases of which were 54.4%,26.0%,45.2%,61.4% and 77.3%,respectively. At the same time,exogenous Ca also improved the pigment contents and photosynthetic parameters(Pn,Tr,Gs)of leaves under Cd stress,the change tendency was similar to morphological indexes,and the largest increases were 44.6%,36.6%,31.8% and 18.4%,respectively. In addition,adding moderate exogenous Ca to garlic seedlings under Cd stress increased mineral elements contents and reduced Cd accumulation of roots,improved appearance and nutritional qualities of garlic bolts and bulbs.