EFFECTS OF POTASSIUM FERTILIZER RATES AND TYPES ON YIELD AND FRUIT QUALITY OF NH01-26 GRAPE IN KHANH HOA PROVINCE

Abstract

The study was conducted to evaluate the effects of potassium fertilizer rates and types on growth, yield, fruit quality and economic efficiency of the grape cultivar NH01-26 grown in Khanh Hoa province. The experiment was carried out over two consecutive cropping seasons in 2023 on the same soil conditions. A split-plot design with three replications was used, in which the main plots were potassium fertilizer types (K) consisting of three treatments (K₁: 100% KCl; K₂: 75% KCl + 25% K₂SO₄ and K₃: 50% KCl + 50% K₂SO₄) and the sub-plots were potassium fertilizer rates (L) with four levels (L₁: 150 kg/ha; L₂: 200 kg/ha as control; L₃: 250 kg/ha and L₄: 300 kg/ha). The results revealed that both potassium fertilizer types and application rates significantly influenced growth, yield components, yield, and fruit quality of NH01-26 grapevine. The combination of K₂L₃ (250 kg/ha; 75% KCl + 25% K₂SO₄) markedly increased the proportion of fruitful shoots and number of clusters per vine, while producing superior yield and fruit quality. The theoretical yield reached 15.954 kg/ha, with an actual yield of 13.252 kg/ha, resulting in net profits of 481.6 million VND/ha (season 1) and 473.0 million VND/ha (season 2). These findings highlight the critical role of potassium, particularly when combining KCl with K₂SO₄, in improving yield, fruit quality and economic efficiency of NH01-26 grapevine, thereby providing a scientific basis for developing sustainable cultivation practices for NH01-26 in Khanh Hoa province.