Response of Two Cotton Genotypes to Five Equidistant Spacing Patterns¹

Abstract

High population densities have been proposed as one way of achieving earlier maturity in cotton (Gossypium hirsutum L.) by increasing the potential number of early fruiting points. But competition among closely spaced plants may adversely affect initiation and set of fruit. Theoretically, competition can be reduced by improving the uniformity of plant distribution. A year field study was conducted to determine the morphological and agronomic reactions of cotton to intraspecific competition over a wide range of plant populations within equidistant spacing configurations. Response to equidistant plant spacing was studied using two genotypes of upland cotton (Gossypium hirsutum L.) with contrasting plant types and five population densities ranging from 38,750 to 620,000 plants/ha in patterns where distance between plants within the row equaled the distance between rows. Vegetative and fruiting components were measured and dry weight determinations were made after destructive fractionation at three harvest dates. Yield, earliness, and fiber quality data were accumulated from weekly harvests of mature bolls. As plant population increased, dry weight per unit land area of all plant components increased except vegetative branches, which decreased. Leaf area index and the number of nodes to the first fruiting branch also increased with higher populations. A smaller, more compact plant developed as plant density increased, which was indicated by reductions in plant height, stem diameter, and number of branches. Boll size, number of seed/boll, seed index, and lint index were all reduced as plant spacing decreased. Retention rate of fruiting forms was apparently much lower in the very high plant densities. Population levels of 79,000 and 155,000 plants/ha were earlier maturing and produced higher lint yield than population levels on either side of this range. These results generally agree with those of investigations of cotton spaced in 1‐m rows. There was no evidence that high population densities in equidistant spacing patterns improve earliness or yield.

Manipulation of dry matter accumulation and partitioning with plant density in relation to yield stability of cotton under intensive management

“…Plant population density is inversely related to mainstem node number and monopodial branch number (Jones and Wells, 1997;Fowler and Ray, 1977;Buxton et al, 1979). Decreased plant density resulted in greater fruiting site production and fruit retention http://dx.doi.org/10.1016/j.fcr.2015.06.008 0378-4290/© 2015 Elsevier B.V. All rights reserved.…”

Vigor de sementes e desempenho agronômico de plantas de algodão

“…O potencial fisiológico das sementes de algodão pode ser influenciado por diversos fatores em campo, antes e/ ou durante a colheita, ou por fatores que ocorrem no período pós-colheita, como a secagem, o beneficiamento e o armazenamento (Freire, 2007).…”

Espaçamentos ultra-adensado, adensado e convencional com densidade populacional variável em algodoeiro

“…Em pesquisa realizada por Smart (1993) Os componentes da produção, de acordo com Fowler & Ray (1977), tais como tamanho de capulho, índice de sementes e fibra e número de sementes por capulho, apresentaram correlação negativa com o estreitamento dos espaçamentos, ou seja, foram menores quanto mais adensados os espaçamentos.…”

“…Entretanto, Fowler & Ray (1977); Lamas (1988) verificaram um aumento na altura de inserção do 1º ramo frutífero nos espaçamentos mais densos. Quanto à densidade, apenas com 14 plantas.m -1 linear a altura de inserção do 1º ramo frutífero foi superior, tal como observado por Yamaoka et al (1982) *, ** Significativos aos níveis de 5% e 1% respectivamente pelo teste de F da análise da variância; Médias seguidas da mesma letra minúscula, na vertical, não diferem entre si pelo teste de Tukey, ao nível de 5% de probabilidade; Médias seguidas da mesma letra maiúscula, na horizontal, não diferem entre si pelo teste de Tukey, ao nível de 5% de probabilidade; D.M.S.…”

“…A plasticidade da planta do algodoeiro é função da configuração de semeadura, ocasionando mudanças nas características morfológicas, fisiológicas e de produção da planta e da lavoura como um todo, bem como a precocidade de colheita (Fowler & Ray, 1977).…”