College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China.
College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China.
Environ Pollut. 2021 Jul 15;281:116999. doi: 10.1016/j.envpol.2021.116999. Epub 2021 Mar 22.
Understanding how the seedling establishment method affects arsenic (As) accumulation in rice is important for safe agricultural production. In a field experiment with three seedling establishment methods and two rice cultivars, the effects of direct seeding (DS), manual transplanting (MT), and seedling throwing (ST) on root morphological indices and the distribution, translocation, and accumulation of As in rice tissues across growth stages were compared. DS method resulted in the greatest accumulation of As in the two rice cultivars and led to more As distributed in aboveground tissues during the entire growth period. Especially in DS brown rice, the concentration of total As increased by 24.0%-40.8%, and that of inorganic As increased by 24.4%-40.0%, compared with the concentrations in MT and ST rice. A multiple regression model was developed with root morphological indices and the total As concentration in brown rice, and the R value of the model was 0.819, which was significant at the 1% level. Compared with the other establishment methods, the thinner diameters, smaller volumes, larger specific surface areas, and greater numbers of root tips in DS rice roots across growth stages promoted As uptake. The concentrations of As in root tips were approximately five times greater than those in the root base, and root tips were the key factor determining the difference in As accumulation in rice roots under the different seedling establishment methods. The results of this study demonstrate that the choice of an appropriate rice seedling establishment method is important to avoid the environmental consequences of As contamination and safely produce rice grain. Therefore, despite the current trend of increased use of DS, transplantation is recommended as a safer pattern of rice seedling establishment in As-contaminated areas.
了解水稻幼苗建立方法如何影响砷（As）积累对于安全农业生产很重要。在一项具有三种幼苗建立方法和两个水稻品种的田间试验中，比较了直接播种（DS）、人工移栽（MT）和抛秧（ST）对根形态指标以及As在水稻组织中的分布、迁移和积累的影响。DS 方法导致两个水稻品种的 As 积累最大，并导致整个生长期间更多的 As 分布在上部组织中。特别是在 DS 糙米中，与 MT 和 ST 水稻相比，总 As 浓度增加了 24.0%-40.8%，无机 As 浓度增加了 24.4%-40.0%。建立了一个包含根形态指标和糙米中总 As 浓度的多元回归模型，模型的 R 值为 0.819，在 1%的水平上显著。与其他建立方法相比，DS 水稻在整个生长阶段的根更细、体积更小、比表面积更大、根尖数量更多，这促进了 As 的吸收。根尖中的 As 浓度约为根基的五倍，并且根尖是决定不同幼苗建立方法下水稻根系中 As 积累差异的关键因素。本研究结果表明，选择合适的水稻幼苗建立方法对于避免 As 污染的环境后果和安全生产水稻至关重要。因此，尽管目前 DS 的使用趋势有所增加，但在 As 污染地区，建议采用移栽作为更安全的水稻幼苗建立模式。
