Análise de crescimento e produtividade de híbridos de mamona de baixo porte em função do espaçamento entre fileiras
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Data
2021-01-26
Autores
Ebertz, Odila Friss
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Universidade Estadual Paulista (Unesp)
Resumo
Os programas de melhoramento genético da mamona têm apostado no desenvolvimento de cultivares e híbridos de baixo porte para alavancar a produtividade dessa cultura, por meio do cultivo mecanizado. A definição do espaçamento entre fileiras e da população de plantas adequada é uma tecnologia simples de ser empregada para maximização da produção. Este estudo teve como objetivo analisar a resposta em crescimento e produtividade de três híbridos de mamona, de baixo porte, quando cultivados em espaçamento convencional e reduzido entre fileiras. O experimento foi conduzido na segunda safra (outono-inverno) do ano de 2019, em Botucatu-SP, utilizando delineamento em blocos casualizados, em esquema fatorial 3 x 2 com 4 repetições. O crescimento das plantas foi analisado através da avaliação da altura de plantas, diâmetro do caule, área foliar e partição de massa de matéria seca, a cada 14 dias durante todo o ciclo, bem como por meio de índices fisiológicos. Por ocasião da colheita, foram avaliadas características agronômicas pertinentes ao porte de plantas e produtividade de grãos e óleo. Houve, ao menos em um momento durante o ciclo, interação significativa entre os híbridos e espaçamentos para altura de plantas, diâmetro do caule, índice de área foliar, massa seca do caule e massa seca de estruturas reprodutivas. Plantas cultivadas sob espaçamento convencional apresentam maior velocidade no incremento de biomassa inicial. A taxa de crescimento relativo decresceu linearmente, durante todo o ciclo, para todos os tratamentos de forma semelhante. A taxa assimilatória líquida permaneceu estável para todos os tratamentos até os 84 DAE, com posterior decréscimo até o final do ciclo. A maior competição entre plantas e o autossombreamento conferiram às plantas cultivadas em espaçamento reduzido maiores razão de área foliar e área foliar específica. Plantas cultivadas sob espaçamento convencional apresentaram maior acúmulo de biomassa acima do solo, assim como maior número de racemos por planta, no entanto, em virtude do aumento da densidade de plantas, tratamentos submetidos ao cultivo em espaçamento reduzido, apresentam maior produtividade de biomassa ao longo do ciclo, e tiveram sua produtividade de grãos equiparada àqueles cultivados em espaçamento convencional. Diferenças entre o acúmulo e partição de biomassa dos híbridos são observados somente ao início do ciclo, não havendo evidências de que a vantagem inicial exerça influência sobre o acúmulo de biomassa final, assim como sobre a produtividade de grãos. Os resultados sugerem que a recomendação do híbrido, assim como do espaçamento entre fileiras a ser utilizado, deve ser realizada com base nos custos de produção.
The castor breeding programs have focused on the development of short height cultivars and hybrids to leverage the yield of this crop, through mechanized cultivation. Defining the row spacing and the appropriate plant population is a simple technology to be used to maximize production. This study aimed to analyze the growth and yield response of three short height castor hybrids, when grown in conventional and reduced row spacing. The experiment was carried out in the second harvest (autumn-winter) of the year 2019, in Botucatu-SP, using a randomized block design, in a 3 x 2 factorial scheme with 4 replications. Plant growth was analyzed by evaluating plant height, stem diameter, leaf area and dry matter partition, every 14 days throughout the cycle, as well as through physiological indexes. At harvest time, agronomic characteristics relevant to plant size and seed and oil yield were evaluated. There was, at least at one point during the cycle, a significant interaction between hybrids and row spacing for plant height, stem diameter, leaf area index, dry mass of stem and dry mass of reproductive structures. Plants grown under conventional spacing present a higher speed in the increment of initial biomass. The relative growth rate decreased linearly, throughout the cycle, for all treatments in a similar way. The net assimilation rate remained stable for all treatments until 84 DAE, with a subsequent decrease until the end of the cycle. The greater competition between plants and self-shading gave plants grown in reduced row spacing greater ratio of leaf area and specific leaf area. Plants grown under conventional row spacing showed a greater accumulation of biomass above the ground, as well as a greater number of racemes per plant, however, due to the increase in plant density, treatments submitted to cultivation in reduced row spacing, present higher biomass productivity along of the cycle, and had their seed yield matched to those grown in conventional spacing. Differences between the accumulation and partition of biomass of the hybrids are observed only at the beginning of the cycle, with no evidence that the initial advantage has an influence on the accumulation of final biomass, as well as on seed yield. The results suggest that the recommendation of the hybrid, as well as the row spacing to be used, should be carried out based on production costs.
The castor breeding programs have focused on the development of short height cultivars and hybrids to leverage the yield of this crop, through mechanized cultivation. Defining the row spacing and the appropriate plant population is a simple technology to be used to maximize production. This study aimed to analyze the growth and yield response of three short height castor hybrids, when grown in conventional and reduced row spacing. The experiment was carried out in the second harvest (autumn-winter) of the year 2019, in Botucatu-SP, using a randomized block design, in a 3 x 2 factorial scheme with 4 replications. Plant growth was analyzed by evaluating plant height, stem diameter, leaf area and dry matter partition, every 14 days throughout the cycle, as well as through physiological indexes. At harvest time, agronomic characteristics relevant to plant size and seed and oil yield were evaluated. There was, at least at one point during the cycle, a significant interaction between hybrids and row spacing for plant height, stem diameter, leaf area index, dry mass of stem and dry mass of reproductive structures. Plants grown under conventional spacing present a higher speed in the increment of initial biomass. The relative growth rate decreased linearly, throughout the cycle, for all treatments in a similar way. The net assimilation rate remained stable for all treatments until 84 DAE, with a subsequent decrease until the end of the cycle. The greater competition between plants and self-shading gave plants grown in reduced row spacing greater ratio of leaf area and specific leaf area. Plants grown under conventional row spacing showed a greater accumulation of biomass above the ground, as well as a greater number of racemes per plant, however, due to the increase in plant density, treatments submitted to cultivation in reduced row spacing, present higher biomass productivity along of the cycle, and had their seed yield matched to those grown in conventional spacing. Differences between the accumulation and partition of biomass of the hybrids are observed only at the beginning of the cycle, with no evidence that the initial advantage has an influence on the accumulation of final biomass, as well as on seed yield. The results suggest that the recommendation of the hybrid, as well as the row spacing to be used, should be carried out based on production costs.
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Palavras-chave
Ricinus communis, Crescimento vegetal, Densidade populacional, Mecanização do cultivo, Produtividade, Plant growth, Population density, Mechanization of cultivation, Yield