Growth Analysis of Chloris elata

ABSTRACT: In Brazil, in agricultural areas where there is no establishment of cover crops in the off season, as well as in citrus orchards in the state of São Paulo, an increase in the infestation of Chloris elata has been observed. This is a perennial species, propagated by seeds and short rhizomes, erect and slightly caespitose. With the objective of evaluating the growth and development of plants from two accessions of C. elata, a greenhouse experiment was conducted. The experimental design was completely randomized, in a 2 (accessions of C. elata) x 15 (evaluation periods) factorial arrangement, with four replications. Fifteen destructive evaluations were performed 14, 21, 28, 35, 42, 49, 56, 63, 70, 77, 84, 91, 98, 112 and 126 days after sowing (DAS) both accessions of C. elata (Itaberaí from Goiás and Matão from São Paulo State). At each evaluation, four plants (replications) were randomly sampled and the height of the main culm, the number of tillers and inflorescences (flower+seed) per plant, the leaf area and dry matter of leaves, culms, roots, inflorescences and total (leaves+culms+roots+ inflorescences) were analyzed. The two accessions showed a slow initial development and growth (up to 63 DAS), mainly in root growth; however, the development of new tillers increased rapidly in the initial phase. During the first 63 DAS, the percentage distribution of dry matter was higher in the foliage, followed by culms and roots. In the final evaluation, the relation was culms followed by leaves, roots and inflorescences. Plants of Matão formed denser clumps, with culms of greater mass, while those from the Itaberaí showed higher height and greater foliage.

摘要：在巴西淡季未布设覆盖作物的农区，以及圣保罗州的柑橘园中，长芒虎尾草（Chloris elata）的侵染为害程度呈上升趋势。该物种为多年生草本，可通过种子与短根茎进行繁殖，株型直立且稍呈丛生状。为评估两个长芒虎尾草居群的植株生长与发育动态，本研究开展了温室盆栽试验。试验采用完全随机析因设计，设置2个长芒虎尾草居群×15个评估周期的因子组合，共设4次生物学重复。分别于播种后14、21、28、35、42、49、56、63、70、77、84、91、98、112及126天（播种后天数，Days After Sowing，以下简称DAS）对两个供试居群（戈亚斯州伊塔贝赖居群与圣保罗州马托居群）开展15次破坏性采样评估。每次评估随机选取4株植株作为重复样本，测定其主茎高度、单株分蘖数与花序（花+种子）数、叶面积，以及叶片、茎秆、根系、花序的干物质质量与总干物质质量（叶片+茎秆+根系+花序）。试验结果表明，两个供试居群的初始生长发育均较为缓慢（播种后63天内），尤以根系生长为甚；但初期新分蘖的产生速度较快。播种后前63天，干物质分配占比最高的器官为叶片，其次为茎秆与根系。在最终评估节点，干物质分配占比顺序变为茎秆、叶片、根系及花序。马托居群形成的草丛更为致密，茎秆生物量更高；而伊塔贝赖居群的植株更高大，叶丛更为繁茂。