Adubação potássica e seu efeito residual sobre a produtividade e a qualidade de tubérculos de batata

Abstract

Resumo: O objetivo deste trabalho foi determinar a dose ótima de K e seu efeito residual sobre a produtividade máxima e a qualidade de tubérculos de batata (Solanum tuberosum). O experimento 1 foi realizado em solo com baixo teor de K (38 mg dm-3), em delineamento experimental de blocos ao acaso, com quatro repetições, cujos tratamentos constituíram-se de cinco doses de K - 0, 110, 220, 440 e 880 kg ha-1 de K2O -, na forma de KCl, aplicados em pré-plantio ao sulco. O experimento 2 foi realizado no mesmo local, com o teor residual do fertilizante aplicado no experimento 1. A fertilização potássica e seu efeito residual influenciaram significativamente o número, a produtividade e a matéria seca dos tubérculos. No entanto, altas doses de K reduziram o teor de matéria seca e a gravidade específica dos tubérculos. O teor residual de K não influenciou todos os componentes de produtividade. A dose de máxima eficiência econômica foi 393,5 kg ha-1 de K2O, que propiciou a máxima produtividade de tubérculos comerciais de 36,2 Mg ha-1, no experimento 1, e de 19,6 Mg ha-1, no experimento 2.

Potassium Fertilization for Fresh Market Potato Production in Tropical Soils

“…The absence of an effect of different K fertilizer application timings (preplanting and prehilling) on the specific gravity of tubers has also been reported in the literature (Kumar et al, 2007, Mohr andTomasiewicz, 2012;Noor et al, 2012;Mello et al, 2018). On the other hand, the specific gravity of potato tubers commonly decreases with the application of KCl, either in the planting furrows (Mohr and Tomasiewicz, 2012;Silva and Fontes, 2016) or before hilling (Mohr and Tomasiewicz, 2012;Silva and Fontes 2016), even under adequate water conditions. According to Mello et al (2018), the influence of K on tuber DM content is complex and dynamic.…”

“…These functions induce shoot growth (Koch et al, 2019), result in a higher number of tubers per plant (Zelelew et al, 2016) and a larger tuber yield (Mohr andTomasiewicz, 2012, Li et al, 2015), increase the total soluble solids (Abd El-Latif et al, 2011;Noor et al, 2012) and protein (Abd El-Latif et al, 2011) contents, and determine the firmness of potato tubers (Mello et al, 2018). On the other hand, K fertilization may also decrease the dry matter (DM) content (Pauletti and Menarin, 2004;Silva and Fontes, 2016), the levels of starch (Li et al, 2015) and protein (Quadros et al, 2009), and the specific gravity of tubers (Mohr and Tomasiewicz, 2012;Silva and Fontes, 2016).…”

“…In soils with high exchangeable K concentrations, tuber yield responses to the application of K fertilizers may be negative (Pauletti and Menarin, 2004;Nava et al, 2007;Li et al, 2015). Under low or medium soil K availability, fertilization increases the number of tubers per plant (Silva and Fontes, 2016) and the tuber yield (Nava et al, 2007;Silva and Fontes, 2016;Mello et al, 2018). However, the poor correlations usually observed between potato crop responses in tuber yields and K fertilization (Mohr and Tomasiewicz, 2012;Shi et al, 2019), or between tuber yields and the initial levels of exchangeable K in soil, suggest that several factors, such as water availability and K interactions with other nutrients, may also affect potato crop productivity (Li et al, 2015).…”

“…However, lower numbers of tubers per plant were observed even with the rates that resulted in the largest numbers of tubers per plant in the soils with medium (228 kg K 2 O ha -1 ) and high (400 kg K 2 O ha -1 ) concentrations of exchangeable K, 9 and 11 tubers per plant, respectively. When studying K fertilization in the planting furrows for 'Agata' potato in a clay soil with a low exchangeable K, Silva and Fontes (2016) observed an increase in the number of marketable tubers per plant and reducing the number of nonmarketable tubers. The increase in the number of tubers per plant is related to the K function in photosynthesis (Koch et al, 2019;Tränkner et al, 2018), which favors a higher energy status in water translocation and nutrient uptake by the roots of potato plants (Zelelew et al, 2016).…”

“…In this condition, the maximum total tuber yield (33.6 Mg ha -1 ) and yield of tubers >45 mm (11.5 Mg ha -1 ) were 107% (17.8 Mg ha -1 ) and 1422% (10.9 Mg ha -1 ) greater, respectively, than the control treatment yields. In the tropical soils of Brazil that have a low initial exchangeable K concentration, other studies have indicated the need for the application of rates between 214 and 393 kg K 2 O ha -1 to obtain the maximum total tuber yield (Nava et al, 2007;Silva and Fontes, 2016). In site-years with medium and high exchangeable K in the soil, the increases in the total tuber yield and yield of tubers >45 mm in diameter were less extreme, and compared to the control yields, the yields with the rate of 200 kg K 2 O ha -1 were approximately 22% (6.2 Mg ha -1 ) and 34% (9.1 Mg ha -1 ) greater (Fig.…”