Relação boro e silício em plantas de algodão cultivadas sob deficiência de boro
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Data
2021-06-21
Autores
Souza Júnior, Jonas Pereira de [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A maior exigência do boro (B) na fase reprodutiva do algodoeiro e baixa disponibilidade no solo é conhecida, implicando no fornecimento deste elemento à cultura, principalmente, via pulverização foliar, embora estudos sejam restritos. Há relatos indicando que o silício (Si) aumenta a produtividade do algodoeiro e outros constatando alto conteúdo de Si na flor e durante o desenvolvimento da fibra do algodão. Isso induziu alguns questionamentos, se o Si poderia auxiliar o B durante o desenvolvimento reprodutivo e se as associações desses elementos poderiam ampliar os seus efeitos benéficos. Para verificar esta interação entre B e Si, realizou-se a presente pesquisa, objetivando-se avaliar o efeito da aplicação foliar de B e de Si, isolados ou associados em algodoeiro, cultivado sob deficiência de B. Este estudo ratificou a importância da aplicação foliar de B no algodoeiro, especialmente por favorecer aspectos fisiológicos, incrementando a produção e viabilidade de grãos de pólen suficiente para aumentar a produtividade e a qualidade da fibra. Os resultados indicaram que o algodoeiro na fase reprodutiva é sensível a deficiência de boro e que é possível melhorar a eficácia da aplicação foliar de B na cultura com adição de Si na calda ao incrementar a eficiência de uso do B da flor, a produção de grãos de pólen. O fornecimento foliar de B também é eficaz em atenuar os efeitos deletérios da deficiência do micronutriente, e a adição de Si à calda boratada incrementou a produção de prolina e de glicina-betaína e reduziu a produção de H2O2 e MDA nas folhas. A aplicação foliar de B e de Si, isolados, na fase reprodutiva do algodoeiro têm efeito semelhante nas trocas gasosas, na produtividade e na qualidade da fibra mas a aplicação da mistura B associado a Si teve efeito somatório na qualidade da produção por incrementar a resistência a ruptura e diminuindo o índice de fibras curtas do algodoeiro.
It is known worldwide that boron (B) is an important nutrient during the reproductive stage of cotton plants (flowering and boll development). This implies in the exogenous supply of this element to the crop, mainly through foliar spraying. Although studies are relatively scarce in the literature, some reports indicate that silicon (Si) could increase the productivity of cotton, other studies indicate that a high Si content is usually found in cotton flower and fiber. This has led to some enquiries, whether Si could be similar to B, playing a similar role, and whether the association of these elements could increase their beneficial effects during the reproductive stage of cotton plants. To verify the interaction between B and Si, this study was carried out aiming to evaluate the positive effects of B and Si foliar applications, associated or not, in cotton plants grown under B deficiency. This study has confirmed the importance of foliar B applied to cotton plants, improving physiological aspects and increasing the production and viability of pollen grains, leading to high productivity and high-quality fiber. Our results indicate that cotton plants, during the reproductive stage, are sensitive to B deficiency, and that it is possible to improve the efficiency of B foliar applications with Si addition, favoring plant efficiency in the use of B in the flowers, increasing the production and the viability of pollen. The foliar supply of B is also efficient in attenuating the deleterious effects of this micronutrient deficiency, and the addition of Si to the borate solution increased the production of proline and glycine-betaine, and reduced the production of H2O2 and MDA in leaves. Therefore, foliar applications of B and Si, isolated, in the reproductive stage of cotton plants, both had a similar effect on gas exchange, as well as fiber productivity and quality. However, the application of B associated with Si (B+Si) had a summatory effect on fiber production and quality by increasing the resistance to rupture and decreasing the cotton short fiber index.
It is known worldwide that boron (B) is an important nutrient during the reproductive stage of cotton plants (flowering and boll development). This implies in the exogenous supply of this element to the crop, mainly through foliar spraying. Although studies are relatively scarce in the literature, some reports indicate that silicon (Si) could increase the productivity of cotton, other studies indicate that a high Si content is usually found in cotton flower and fiber. This has led to some enquiries, whether Si could be similar to B, playing a similar role, and whether the association of these elements could increase their beneficial effects during the reproductive stage of cotton plants. To verify the interaction between B and Si, this study was carried out aiming to evaluate the positive effects of B and Si foliar applications, associated or not, in cotton plants grown under B deficiency. This study has confirmed the importance of foliar B applied to cotton plants, improving physiological aspects and increasing the production and viability of pollen grains, leading to high productivity and high-quality fiber. Our results indicate that cotton plants, during the reproductive stage, are sensitive to B deficiency, and that it is possible to improve the efficiency of B foliar applications with Si addition, favoring plant efficiency in the use of B in the flowers, increasing the production and the viability of pollen. The foliar supply of B is also efficient in attenuating the deleterious effects of this micronutrient deficiency, and the addition of Si to the borate solution increased the production of proline and glycine-betaine, and reduced the production of H2O2 and MDA in leaves. Therefore, foliar applications of B and Si, isolated, in the reproductive stage of cotton plants, both had a similar effect on gas exchange, as well as fiber productivity and quality. However, the application of B associated with Si (B+Si) had a summatory effect on fiber production and quality by increasing the resistance to rupture and decreasing the cotton short fiber index.
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Palavras-chave
Adubação, Estresse oxidativo, Pulverização e polvilhação na agricultura, Algodoeiro