Efeito na qualidade do fruto da aplicação de dois reguladores de crescimento na cultura da actinídia (Actinidia deliciosa cv “Hayward”)
Data
2022-08-08
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A cultura da actinídia apresenta um elevado potencial de crescimento, visto ser uma cultura relativamente recente e com muita procura. Os mercados procuram principalmente os kiwis de maior calibre pois são os mais valorizados pelo consumidor. Uma vez que esta cultura é bastante dispendiosa, é importante para os produtores conseguirem obter frutos com calibres superiores e produtividades elevadas, de forma a conseguiram rentabilizar o investimento. Assim, com este estudo pretende-se verificar o efeito que os reguladores de crescimento podem ter no aumento do calibre e produtividade desta cultura, mas também o seu efeito na qualidade dos frutos. Para tal, procedeu-se à aplicação de dois reguladores de crescimento, o ácido (4-cloro-2-metilfenoxil) acético (MCPA) e o forclorfenurão, a três concentrações diferentes, recorrendo também a uma testemunha, onde não se aplica qualquer regulador de crescimento. Para acompanhar os frutos ao longo do desenvolvimento procedeu-se à determinação dos diâmetros desde do vingamento dos mesmos até à sua colheita. Após a colheita procedeu-se a avaliação do calibre dos frutos e da produtividade nos diferentes tratamentos e concentrações. Por último foram analisados em laboratório diferentes parâmetros para avaliar a qualidade dos frutos: biometria (diâmetros, peso e rácios), textura, parâmetros cromáticos, teor em sólidos solúveis (TSS), pH, % de MS, Vitamina C, fenólicos totais, atividade antioxidante, ácidos orgânicos, açúcares livres, pigmentos, carotenoides e luteína. Os resultados obtidos indicaram que os reguladores de crescimento conduziram a frutos de maior calibre e a produtividades mais elevadas, destacando-se o regulador de crescimento MCPA, que obteve os melhores resultados. Para além disso, verificou-se também que as concentrações mais elevadas dos reguladores de crescimento produziram melhores resultados ao nível dos calibres. Quanto à qualidade dos frutos, pode-se constatar que os frutos em que não foi aplicado qualquer regulador de crescimento apresentaram valores mais baixos na textura e valores mais elevados de TSS e % de MS, o que indica que provavelmente atingiram uma maturação mais temporã. Estes valores podem resultar das plantas testemunha apresentarem em geral produtividades mais baixas e por isso menor competição por fotoassimilados. Apesar disso, os restantes parâmetros indicam que a qualidade do fruto não foi afetada pelos reguladores. Em suma, este estudo permite concluir que os reguladores de crescimento podem ser benéficos para o produtor, permitindo atingir melhores resultados económicos, sem afetar a qualidade final do fruto.
Actinidia crop has a high growth potential, since it is a relatively recent crop with high demand. The markets are mainly looking for kiwis with higher caliber thus these are the most valued by the consumer. Since this crop is highly expensive, it is important for producers to be able to obtain fruits with higher calibers and yields, in order to get a return on their investiment. According to this, this study aims to verify the effect that growth regulators may have in the increase of the caliber and yield of this crop, but also the effect that they may have on the quality of the fruits. To do this, two growth regulators, (4-chloro-2-methyphenoxyl) acetic acid (MCPA) and forchlorfenuron, were applied at three different concentrations each, and also using a control, where no growth regulator was applied. In order to follow the fruit development, we determined the diameters from the fruit set until harvest. After the harvest, the caliber of the fruits and the yield were evaluated in the different treatments and concentrations. Finally, different parameters were analyzed in laboratory to evaluate the fruit quality: biometry (diameters, weight and ratio), texture, chromatic parameters, soluble solid content (SSC), pH, % dry matter (DM), vitamin C, total phenolics, antioxidant activity, organic acids, free sugars, pigments, carotenoids and lutein. The results indicated that the growth regulators led to fruits of greater caliber and higher yield, with the growth regulator MCPA standing out, which obtained the best results. Furthermore, it was also found that increases in the concentration of growth regulators led to even better results at the size level. As for fruit quality, it can be stated that the fruits in which no growth regulator was applied had lower values for texture and higher values for SSC and % of DM, indicating that they probably reached maturity earlier. These values may result from the fact that the control plants generally had lower yield and therefore less competition for photoassimilates. Despite this, the other parameters indicate that the quality of the fruit was not affected by the regulators. In summary, this study concludes that the growth regulators may be beneficial for the producer, allowing to achieve better economic results, without affecting the final quality of the fruit.
Actinidia crop has a high growth potential, since it is a relatively recent crop with high demand. The markets are mainly looking for kiwis with higher caliber thus these are the most valued by the consumer. Since this crop is highly expensive, it is important for producers to be able to obtain fruits with higher calibers and yields, in order to get a return on their investiment. According to this, this study aims to verify the effect that growth regulators may have in the increase of the caliber and yield of this crop, but also the effect that they may have on the quality of the fruits. To do this, two growth regulators, (4-chloro-2-methyphenoxyl) acetic acid (MCPA) and forchlorfenuron, were applied at three different concentrations each, and also using a control, where no growth regulator was applied. In order to follow the fruit development, we determined the diameters from the fruit set until harvest. After the harvest, the caliber of the fruits and the yield were evaluated in the different treatments and concentrations. Finally, different parameters were analyzed in laboratory to evaluate the fruit quality: biometry (diameters, weight and ratio), texture, chromatic parameters, soluble solid content (SSC), pH, % dry matter (DM), vitamin C, total phenolics, antioxidant activity, organic acids, free sugars, pigments, carotenoids and lutein. The results indicated that the growth regulators led to fruits of greater caliber and higher yield, with the growth regulator MCPA standing out, which obtained the best results. Furthermore, it was also found that increases in the concentration of growth regulators led to even better results at the size level. As for fruit quality, it can be stated that the fruits in which no growth regulator was applied had lower values for texture and higher values for SSC and % of DM, indicating that they probably reached maturity earlier. These values may result from the fact that the control plants generally had lower yield and therefore less competition for photoassimilates. Despite this, the other parameters indicate that the quality of the fruit was not affected by the regulators. In summary, this study concludes that the growth regulators may be beneficial for the producer, allowing to achieve better economic results, without affecting the final quality of the fruit.
Descrição
Dissertação de Mestrado em Engenharia Agronómica
Palavras-chave
Kiwi , Regulador de crescimento