Growth and physiological characteristics of the weed false johnsongrass ( Sorghum arundinaceum (Desv.) Stapf)

ABSTRACT Sorghum arundinaceum (Desv.) Stapf is a weed that belongs to the Poaceae family and is widespread throughout Brazil. Despite the frequent occurrence, infesting cultivated areas, there is little research concerning the biology and physiology of this species. The objective of this research was to evaluate the growth, carbon partitioning and physiological characteristics of the weed Sorghum arundinaceum in greenhouse. Plants were collected at regular intervals of seven days, from 22 to 113 days after transplanting (DAT). In each sample, we determined plant height, root volume, leaf area and dry matter, and subsequently we perfomed the growth analysis, we have determined the dry matter partitioning among organs, the accumulation of dry matter, the specific leaf area, the relative growth rate and leaf weight ratio. At 36, 78 and 113 DAT, the photosynthetic and transpiration rates, stomatal conductance, CO2 concentration and chlorophyll fluorescence were evaluated. The Sorghum arundinaceum reached 1.91 in height, with slow initial growth and allocated much of the biomass in the roots. The photosynthetic rate and the maximum quantum yield of FSII are similar throughout the growth cycle. At maturity the Sorghum arundinaceum presents higher values of transpiration rate, stomatal conductance and non-photochemical quenching coefficient (NPQ).

摘要：拟高粱（Sorghum arundinaceum (Desv.) Stapf）属于禾本科（Poaceae）杂草，在巴西境内广泛分布。尽管该杂草频繁侵染栽培农田，但目前针对其生物学与生理学特性的研究仍较为匮乏。本研究旨在评估温室条件下拟高粱的生长、碳分配及生理学特性。试验于移栽后22至113天（移栽后天数，days after transplanting, DAT）期间，每隔7天采集植株样本；每次采样均测定株高、根体积、叶面积与干物质含量，随后开展生长分析，测定各器官的干物质分配比例、干物质积累量、比叶面积、相对生长率及叶重量比。在移栽后36、78和113 DAT时，测定其光合速率、蒸腾速率、气孔导度、CO₂浓度及叶绿素荧光参数。结果显示，拟高粱最终株高达1.91，初始生长较为缓慢，且将大量生物量分配至根系。整个生长周期内，其光合速率与光系统II（PSII）的最大量子产额均保持稳定。成熟期时，拟高粱的蒸腾速率、气孔导度及非光化学淬灭系数（NPQ）均处于较高水平。