PENGARUH FREKUENSI PEMUPUKAN NPK PADA PERTUMBUHAN DAN PRODUKSI TANAMAN KENTANG (Solanum tuberosum L.)

Abstract

Potato (Solanum tuberosum L.) is a major horticultural crop and a key carbohydrate source after rice, maize, and wheat. Its high economic value and suitability for highland cultivation make it an important commodity for food security. This study aimed to evaluate the effect of NPK fertilization frequency on the growth and yield of the Superjohn potato variety. The experiment was conducted at the Experimental Farm of Sam Ratulangi University, Manado, from March to June 2025, using a Randomized Block Design (RBD) with four treatment frequencies: twice, three times, four times, and five times. Each treatment received a total of 15 grams of NPK per plant, applied via watering (kocor) in divided doses. Observed variables included plant height, leaf number, branch number, tuber weight, tuber count, and tuber size classes (SS, S, M, and L). Results showed that fertilization frequency had no statistically significant effect on any of the growth or yield parameters. However, the five-time application treatment (P4) consistently yielded the highest average values numerically across most variables. High rainfall during the study period was suspected to cause nutrient leaching, particularly nitrogen, and waterlogged soil conditions that inhibited root respiration and nutrient uptake.

 Keywords: Potato, fertilization frequency, yield