THE EFFECT OF RATIO OF NPK FERTILIZERS DURING THE FRUIT DEVELOPMENT STAGE ON THE YIELD AND PHYSIOLOGICAL DISORDER SYMPTOMS OF FLESH OF MUSANG KING DURIAN (Durio zibethinus Murr.) ON THE OFF-SEASON IN TAN BINH COMMUNE, CAN THO CITY

Abstract

The study aims to determine the effectiveness of NPK fertilizer ratios during the fruit development stages on physiological disorders symptoms (PDS) in 7-year-old Musang King durian trees in Tan Binh commune, Can Tho city on the off-season from February to August 2024. The experiment was arranged in a randomized complete block design (RCBD) with six treatments, five replications, each experimental unit corresponding to one tree. The six treatments involved different ratio of NPK fertilizer applied at three stages: 30, 45, 60 days after fruit set (DAFS), with 1,000 grams of fertilizer applied per tree per time. The results revealed that the ratio of NPK fertilizer applied during the fruit development stages significantly affected the fruit weight components, yield, fruit quality, and PDS in MK’s flesh. Applying NPK fertilizer with high ratio of nitrogen (3: 1: 1, 2: 1: 1) at 30 and 45 days after fruit set (DAFS), then increasing ratio of potassium (2: 1: 3) at 60 DAFS helps boost yield but also increases the incidence of PDS (23.6 - 29.6%). Conversely, applying high ratio of nitrogen (2: 1: 1) at 30 DAFS, then elevated ratio of potassium (2: 1: 3 and 1: 1: 3) at 45 and 60 DAFS, not only improves yield and fruit quality but also reduces PDS in MK durians. It is recommended to apply NPK fertilizer ratios for 7-year-old MK durian trees during fruit development in the following: 2: 1: 1 (30 DAFS), 2: 1: 3 (45 DAFS), 1: 1: 3 (60 DAFS), with a dosage of 1.000 grams/tree/time, to achieve high yield, and reduce PDS on the off-season.