Características morfoagronômicas do milho submetido a diferentes níveis de desfolha manual

Abstract

Morphoagronomic characteristics of maize in response to different levels of defoliationThe present study was conducted to evaluate the damage caused by defoliation in maize. The experiment was carried out in 2005/2006 at Roma Farm, Ituverava-SP, using the triple hybrid CODETEC 304®. The experiment consisted of split plots (split-plot), which were distributed at random in three blocks, with the main treatment manual defoliation (30%, 40%, 60% and 80% defoliation) in the plots and as the secondary treatment the phenological phases (D1, D2 and D3) with three replicates for each treatment and a control plot (0% defoliation) for each block. It was evaluated the production of plots (g/m 2 ), the average size of the spikes (cm) and the average weight of thousand grains (g). According to the results, it was concluded that the source-sink relations were negatively affected, and the treatment with 80% defoliation was the one that most affected all variables, thus, it is a level of defoliation that is responsible for the largest losses, with no means of compensation for the maize crop.

Effect of Artificial Defoliation in Different Levels on Agronomic Characteristics in Corn Culture

“…Grain development is a result of the balance between the plant ability to produce photoassimilates (source) for the grains and its own potential for the use of available substrates (Pereira et al, 2012). Thus, it can be affirmed that the loss of leaves by the corn plant directly affects the mass of grains, consequently being able to reduce the productivity of the area.…”

“…In addition, the crop has low capacity to compensate foliar losses (Pereira et al, 2012). The loss of leaves by the plant is a stress that impairs the development of the crop, because it reduces the leaf area of the plant and consequently limits the interception of the solar radiation, reducing the photosynthetic capacity and the biomass production (Picoli Junior, 2011).…”

“…The corn crop has low capacity to compensate for leaf losses, since its effective capacity to compensate for spaces and leaf plasticity are reduced (Pereira et al, 2012).…”

Desenvolvimento e produtividade de grãos de milho submetido a níveis de desfolha

“…Os resultados do presente trabalho são indicativos de que, mesmo havendo um longo período para a planta se recuperar da desfolha, isso não ocorreu de forma efetiva, diferentemente do relatado por outros autores em trabalhos anteriores (Magalhães & Durães, 2006;Pearson & Fletcher, 2009;Pereira et al, 2012;Sangoi et al, 2014). Contudo, no presente trabalho, as médias de produtividade foram superiores às obtidas por esses autores, o que indica que, em lavouras nas quais se almejem altos tetos produtivos, pequenas perdas de área foliar, nos estádios iniciais de desenvolvimento, afetam significativamente a produtividade.…”

“…A manutenção da integridade foliar é importante, pois a folha é o principal órgão responsável pela fotossíntese; além disso, a cultura apresenta baixa capacidade de compensar as perdas foliares, já que sua prolificidade, capacidade efetiva de compensação de espaços e plasticidade foliar são reduzidas (Strieder et al, 2007;Pereira et al, 2012).…”