Relative Competitiveness Between Cultivated and Weedy Rice under Full and Low Light

C.E Schaedler,W Lubian,P.C Lima,D.M Chiapinotto

doi:10.1590/s0100-83582020380100039

Abstract

ABSTRACT: Cultivated and weedy rice biotypes exhibit morphophysiological variations under low light, affecting competition between plants. The aim of this study was to assess relative competitiveness between cultivated and weedy rice under full and low light. Three experiments were conducted in a greenhouse, using a completely randomized design with four repetitions. The treatments in the experiment I were arranged in additive series while in the experiments II and III treatments were arranged in replacement series. Experiments II and III were carried out concomitantly to assess coexistence between the rice cultivar and weedy rice. The treatments consisted of different plants proportions: 100:0 (cultivated rice monoculture), 75:25, 50:50, 25:75 and 0:100 (weedy rice monoculture), keeping the total plant population obtained in experiment I (240 plants m-2) constant. Experiment II was conducted with full solar radiation and III under 50% light. The variables analyzed were shoot dry weight and plant height, 35 days after emergence (DAE). Competition among plants was evaluated via graphs and by interpreting competition indices. Concerning shoot dry weight, mutual losses were recorded between competitors, whereas equal competition for resources was observed for plant height. Weedy rice was more competitive than cultivated rice regardless of the light environment assessed, indicating the need for integrated methods to control this weed.

Highlights

Competition between weeds and cultivated plants is one of the main causes of yield losses in agricultural crops
Weedy rice belongs to the same taxon of the cultivated rice (Oryza sativa L.), characterizing intraspecific competition (Roush et al, 1989)
Nutrients and sunlight quickly become the most limiting resources (Burgos et al, 2006). Distinct morphophysiological traits such as vigor, high tiller production and height give weedy rice a competitive advantage (Abraham and Jose, 2014). These characteristics are responsible for larger leaf area and higher photosynthetic capacity (Dai et al, 2016), enabling plants to better compete for solar radiation (Streck et al, 2008a)

Summary

Introduction

Competition between weeds and cultivated plants is one of the main causes of yield losses in agricultural crops. Nutrients and sunlight quickly become the most limiting resources (Burgos et al, 2006). Distinct morphophysiological traits such as vigor, high tiller production and height give weedy rice a competitive advantage (Abraham and Jose, 2014). These characteristics are responsible for larger leaf area and higher photosynthetic capacity (Dai et al, 2016), enabling plants to better compete for solar radiation (Streck et al, 2008a)

Objectives

Methods

Results