PERIODS OF WEED INTERFERENCE ON TRANSGENIC COTTON 'IMACD 6001LL'

Marcos Paulo Da Silva,Fernanda Nunes Bressanin,Mariana Casari Parreira,Pedro Luis Da Costa Aguiar Alves

doi:10.1590/1983-21252016v29n214rc

Marcos Paulo Da Silva, Fernanda Nunes Bressanin + Show 2 more

Open Access

https://doi.org/10.1590/1983-21252016v29n214rc

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Abstract

ABSTRACT: The objective of this study was to determine the periods of weed interference and its impact on productivity of cotton 'IMACD 6001LL'. The experiment was conducted in Jaboticabal, São Paulo, the second crop in 2011 and consisted of two treatment groups: the first culture remained free of competing weeds since of emergence up different periods of its development: (0-15 , 0-25, 0-35, 0-45, 0-55, 0-65, 0-75 and 0-183 days - harvest). In the second treatment group was held to the contrary: the crop was in harmony with the weeds since of emergence up to the same stages of development described above. The treatments were arranged in a randomized block design in four replications. During these periods was evaluated dry matter accumulation by weeds. The cotton yield data were subjected to regression analysis and resulting in a CPWC of 35 DAE, the CPWR was 133 DAE and .The weed community was composed mainly of Raphanus raphanistrum, Amaranthus spp., Cyperus rotundus, Alternanthera tenella and Eleusine indica. Living with this community throughout the cycle resulted in reduction almost 85% in cotton yield.

Highlights

Brazil is among the five largest producers of cotton, alongside countries like China to India, the US and Pakistan
The critical period of weed control (CPWC) is the period during the crop cycle in which weeds must be controlled in order to avoid reduction in crop yield
The CPWC starts in the critical timing of weed removal (CTWR), corresponding to the maximum amount of time that early-season weed competition can be tolerated by the crop before it suffers yield reduction, and it ends in the critical weed-free period (CWFP), corresponding to the minimum weed-free period required to prevent yield reductions (KNEZEVIC et al, 2002).Theoretically, crop yield is only marginally influenced if the weed control occurs before or after the CPWC

Summary

Introduction

Brazil is among the five largest producers of cotton, alongside countries like China to India, the US and Pakistan. In the last three seasons, the Brazilian production of plumes reached 1.7 million tons, the largest producer of this matter in Latin America (ABRAPA, 2015). The critical period of weed control (CPWC) is the period during the crop cycle in which weeds must be controlled in order to avoid reduction in crop yield. The CPWC starts in the critical timing of weed removal (CTWR), corresponding to the maximum amount of time that early-season weed competition can be tolerated by the crop before it suffers yield reduction, and it ends in the critical weed-free period (CWFP), corresponding to the minimum weed-free period required to prevent yield reductions (KNEZEVIC et al, 2002).Theoretically, crop yield is only marginally influenced if the weed control occurs before or after the CPWC

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