Periods of weed interference in maize crops cultivated in the first and second cycles

Abstract

The interference of weeds in maize production may be reflected in grain yield losses that vary as a function of the density, stage and degree of aggressiveness of the species present. In the agricultural ecosystem, crops and weeds demand light, water, nutrients and space, which are frequently not available in sufficient quantities, leading to competition. The aim of this work was to determine the period of interference of weed plants, in particular of naked crabgrass (Digitaria nuda) on maize crop in the first and second harvest. The treatments were defined as increasing periods of coexistence and increasing control of weed community (7, 14, 21, 28, 35, 42, 49, and 56 days), two more controls, a control including one with weed control until the end of the culture cycle and another with coexistence until the harvest. For each period, were evaluated the stand of maize plants, length of ear, number of grains per row, number of rows per ear, cob, 100-grain weight, and grain productivity. The data obtained were subjected to analysis of variance using the F test, with average treatments compared using Tukey's test at 5% probability. Crop productivity was evaluated by means of regressions, the critical periods of interference were estimated. The critical timing of weed removal was 25 days for both harvests. The critical weed free period was 54 and 27 days for the first and second harvest respectively. For the conditions of the first and second harvest, the critical period of weed control was of 29 and 2 days respectively. Key words: Digitaria nuda. Naked crabgrass. Competition. Phytosociology. Weed interference. Zea mays. ResumoA interferência de plantas daninhas no milho pode refletir em perdas na produtividade de grãos que variam em função da densidade, estágio e grau de agressividade das espécies presentes. No ecossistema agrícola, a cultura e planta daninha possuem demandas por luz, água, nutrientes e espaço, que na maioria das vezes, não estão disponíveis em quantidades suficientes, estabelecendo-se a competição. O objetivo desse trabalho foi determinar o período de interferência de plantas de plantas daninhas em especial do capim-colchão (Digitaria nuda) na cultura do milho na primeira e segunda safra. Os tratamentos foram divididos em períodos crescentes de convivência e de controle da comunidade infestante (7; 14; 21; 28; 35; 42; 49 e 56 dias), mais duas testemunhas, uma com controle até o fim do ciclo da cultura e outra com convivência até a colheita. Para cada período foram avaliadas o estande de plantas de milho, comprimento das espigas, número de grãos por fileiras, número de fileiras por espiga, massa de 100 grãos e produtividade de grãos. Os dados obtidos foram submetidos à análise de variância

Interference Periods of Weeds in Maize in No-Tillage and Conventional Systems at High Altitudes

“…No significant differences were found for the weight of 100 grains in the periods of coexistence and weed control to which the maize hybrids (P2530™ and P3271H™) were subjected, as well as between the soil management systems under study ( Figure 4A, B). These results corroborate those reported by Campos et al (2016), in which only the maize grown in the first crop season showed this behavior. Zagonel et al (2000) observed that the delay in the weed control season did not affect the weight of 100 grains in the maize crop.…”

Nutritional Value of Marandú Palisade Grass According to Increasing Coexistence Periods with Weeds

“…Researches on weed interference effects on grasses such as maize (Campos et al, 2016) and sorghum (Rodrigues et al, 2010) have shown that weeds may represent an hazard for the establishment, growth and biomass production of these fodder plants, especially if the biological 3 competition relation is established at early stages of their development. However, no research was conducted on the nutritional aspects of these species.…”

Revisiting the concept of the critical period of weed control

“…Mahajan et al (2014) found that rice genotypes PR-115 and H-97158 could not compete with weeds and were regarded as the worst weed competitors while PR-120, IR88633 and IR83927 were able to compete with weeds. Although Campos et al (2016) noticed a temporal variation in CWFP in maize between years; 54 days after emergence (DAE) in the first year v. 27 DAE in the second year. In general, a long CPWC is an indication of more competitive weeds or less competitive crops (Ghosheh et al, 1996).…”

“…Although Campos et al . (2016) noticed a temporal variation in CWFP in maize between years; 54 days after emergence (DAE) in the first year v . 27 DAE in the second year.…”