Abstract:

Maize is a potential phytoremediation material. The cadmium (Cd) accumulation characteristics of maize inbred lines with high and low grain cadmium accumulation under cadmium stress at different growth stages were investigated. In this study, pot experiments of maize inbred lines with high (‘Zhong69’) and low (‘K22’) Cd accumulation in grains were carried out at Anhui Agricultural University’s experimental farm. The biomass and Cd concentration of roots, stems, leaves and grains at seedling stage, jointing stage, tasseling stage, filling stage, milk-ripe stage, wax-ripe stage and full-ripe stage were measured. The effects of Cd concentration in different maize tissues at different growth stages on total biomass and their contributions were analyzed by stepwise regression method. The results showed that the growth of ‘Zhong69’ were seriously inhibited by Cd stress, but it did not affect ‘K22’. Under Cd stress, the Cd concentrations in roots, stems, leaves and grains of ‘Zhong69’ were 1.07-2.02 times, 3.48-14.0 times, 7.87-23.8 times and 65.4 times those of ‘K22’ at different growth stages, respectively. The cadmium accumulation characteristics in two maize inbred lines showed the following order: leaves > stems > root s> grains in ‘Zhong69’, and the proportion of leave Cd accumulation to the total amount of Cd accumulation in the whole plant ranged from 42.3% to 92.0%, showing a decreasing-and-increasing trend during different growth stages; the cadmium accumulation characteristics showed that roots > leaves > stems > grains in ‘K22’, and the proportion of root Cd accumulation to the total amount of Cd accumulation in the whole plant ranged from 37.8% to 66.2% during different growth stages. Under Cd stress, the Cd concentrations of ‘Zhong69’ and ‘K22’ were the highest at the seedling stage, reaching 6.60 mg?kg^-1 and 4.60 mg?kg^-1, respectively. The accumulation of Cd was the lowest at the seedling stage, which was 3.63 μg and 0.96 μg, for both varieties respectively, and increased with the growth period, and the highest at the filling stage, which was 222 μg and 77.5 μg, respectively. Stepwise regression analysis showed that the total biomass of ‘Zhong69’ was mainly affected by the Cd concentration in stems and leaves, showing a significant negative correlation (P=0.028) under Cd stress, while the total biomass of ‘K22’ was only affected by the Cd concentration in stems, showing a significant positive correlation (P=0.008). This study showed that the main compartments to accumulate Cd were leaves in ‘Zhong69’ and roots in ‘K22’. Cd concentrations in stems and leaves were potential influencing factors for the total biomass of maize plants. The period from the seedling to filling stage was important for maize to absorb Cd, while the filling stage was the critical period for restoring Cd-contaminated soil.

Key words: maize inbred lines, cadmium accumulation, growth stages, phytoremediation

摘要：

玉米是潜在的植物修复材料，研究镉（Cd）胁迫下玉米籽粒镉高/低积累自交系不同生育期的镉累积特性，为选育籽粒Cd低积累和高富集玉米品种提供参考。于安徽农业大学试验农场对籽粒镉高积累（‘Zhong69’）和低积累（‘K22’）的玉米自交系进行盆栽试验，测定苗期、拔节期、抽雄期、灌浆期、乳熟期、蜡熟期、完熟期7个生育期的根、茎、叶和籽粒4个部位的生物量、Cd质量分数等指标，并采用逐步回归法分析玉米不同生育期各部位Cd质量分数对总生物量的影响及其贡献程度。结果表明，Cd胁迫抑制‘Zhong69’生长，而对‘K22’生长影响较小。Cd胁迫下‘Zhong69’各生育期的根、茎、叶和籽粒Cd质量分数分别是‘K22’的1.07－2.02、3.48－14.0、7.87－23.8、65.4倍。两自交系镉积累特性分别为：‘Zhong69’为叶>茎>根>籽粒，叶片Cd积累量占整株总量比例在42.3%－92.0%之间，随生育期呈先降后升趋势；‘K22’为根>叶>茎>籽粒，根部Cd积累量占整株总量比例在37.8%－66.2%之间，无明显变化规律。Cd胁迫下，‘Zhong69’和‘K22’的Cd质量分数在苗期最高，分别为6.60 mg?kg^?1和4.60 mg?kg^?1；Cd积累量在苗期最低，分别为3.63 μg和0.96 μg，在灌浆期达到最高，分别为222 μg和77.5 μg。逐步回归分析表明，Cd胁迫下，‘Zhong69’总生物量主要受茎部和叶片Cd质量分数共同影响，呈显著负相关（P=0.028），而‘K22’总生物量仅受茎部Cd质量分数影响，呈显著正相关（P=0.008）。该研究表明，‘Zhong69’和‘K22’的主要Cd积累部位分别为叶片和根部；茎部和叶片Cd质量分数是影响玉米植株总生物量的潜在影响因素，苗期至灌浆期是玉米吸收Cd的重要时期，灌浆期是修复Cd污染土壤的关键时期。

关键词: 玉米自交系, 镉累积, 生育期, 植物修复