ABSTRACT

We investigated how plant inoculation with two diazotrophic bacteria would influence the modulation of root architecture and parameters associated with N uptake rate under high and low NO₃⁻ availability. The treatments were arranged in a 2 × 3 factorial design, the first factor being N dose (0.3 and 3.0 mM, or low and high N, respectively) and the second being inoculation with Herbaspirillum seropedicae strain ZAE94 (Hs-ZAE94), Azospirillum brasilense strain Sp245 (Ab-Sp245) and an uninoculated control. The parameters evaluated were: root architecture, mineral N in the growth solution, soluble metabolites, and activities of two N enzymes, dry mass, N accumulation, and the ratio of plant dry mass to N accumulation (NUE). Plant parameters improved with higher N availability. Only under high N, the inoculation with Ab-Sp245 brought about a change in root architecture with an improvement in root surface area, which was in agreement with an increased plant dry matter, N accumulation, and NUE, which was not always observed on either sampling date, 24 and 32 days after transfer to the hydroponic system. The shift in root architecture and the maintenance of N uptake per unit of root area by inoculation with Ab-Sp245 was likely the main effect.

摘要

_{我们研究了在高和低 NO 3} ^-可用性下，用两种固氮细菌接种植物将如何影响根结构和与 N 吸收率相关的参数的调节。处理以 2 × 3 因子设计排列，第一个因素是 N 剂量（分别为 0.3 和 3.0 mM，或低和高 N），第二个因素是接种Herbaspirillum seropedicae ZAE94 ( Hs -ZAE94)、Azospirillum brasilense菌株 Sp245 ( Ab-Sp245) 和未接种的对照。评估的参数是：根结构、生长溶液中的矿物氮、可溶性代谢物和两种氮酶的活性、干质量、氮积累和植物干质量与氮积累的比率 (NUE)。随着氮的可用性提高，工厂参数得到改善。仅在高 N 下，接种Ab -Sp245 导致根结构发生变化，根表面积增加，这与增加的植物干物质、N 积累和 NUE 一致，这在两者中并不总是观察到采样日期，转移到水培系统后 24 天和 32 天。通过接种Ab -Sp245，根结构的变化和每单位根面积 N 吸收的维持可能是主要影响。