PERTUMBUHAN DAN PRODUKSI UBI JALAR (Ipomoea batatas L.)PADA BERBAGAI KOMBINASI PUPUK NPK DAN PGPR

Abstract

Produktivitas ubi jalar masih terkendala oleh rendahnya efisiensi pemupukan anorganik. Pemanfaatan Plant Growth Promoting Rhizobacteria (PGPR) berpotensi meningkatkan efisiensi serapan hara dan hasil tanaman. Penelitian ini bertujuan menganalisis pengaruh kombinasi pupuk NPK (15-10-12) dan PGPR Bacillus subtilis QST 713: 109 CFU/g pada pertumbuhan dan produksi ubi jalar (Ipomoea batatas L.). Penelitian menggunakan Rancangan Kelompok Lengkap Teracak (RKLT) faktor tunggal dengan tujuh perlakuan yaitu tanpa pemupukan (T0), PGPR Bacillus subtilis (T1), pupuk NPK 100% (T2), kombinasi PGPR Bacillus subtilis dan NPK 25% (T3), kombinasi PGPR Bacillus subtilis dan NPK 50% (T4), kombinasi PGPR Bacillus subtilis dan NPK 75% (T5), kombinasi PGPR Bacillus subtilis dan NPK 100% (T6) dan empat ulangan. Peubah yang diamati meliputi pertumbuhan vegetatif, komponen hasil, dan efektivitas agronomi relatif (RAE). Hasil penelitian menunjukkan bahwa kombinasi pupuk NPK dan PGPR berpengaruh nyata pada jumlah umbi per petak, bobot umbi per petak, jumlah umbi sehat, dan berbeda sangat nyata pada jumlah umbi terserang hama. Kombinasi PGPR B. subtilis dengan konsentrasi 2,5 ml L-1 + NPK 25% (37,5 kg) menghasilkan bobot umbi per petak dan nilai RAE tertinggi yaitu 173,78%, sedangkan Bacillus subtilis + NPK 100% menghasilkan jumlah umbi sehat tertinggi yang tidak terserang Cylas formicarius. Penggunaan PGPR memungkinkan pengurangan dosis pupuk NPK 25% sampai dengan 75% dari dosis standar tanpa menurunkan hasil.

Sweet potato productivity is still constrained by the low efficiency of inorganic fertilizer use. The application of Plant Growth Promoting Rhizobacteria (PGPR) has the potential to improve nutrient uptake efficiency and crop yield. This study aimed to analyze the effects of combinations of NPK fertilizer (15–10 12) and PGPR Bacillus subtilis QST 713 (1 × 10? CFU g?¹) on the growth and yield of sweet potato (Ipomoea batatas L.). The experiment was arranged in a single-factor randomized complete block design with seven treatments, namely without fertilization (T0), PGPR Bacillus subtilis (T1), 100% NPK fertilizer (T2), PGPR Bacillus subtilis + 25% NPK (T3), PGPR Bacillus subtilis + 50% NPK (T4), PGPR Bacillus subtilis + 75% NPK (T5), and PGPR Bacillus subtilis + 100% NPK (T6), with four replications. Observed variables included vegetative growth, yield components, and relative agronomic effectiveness (RAE). The results showed that the combination of NPK fertilizer and PGPR significantly affected the number of tubers per plot, tuber weight per plot, and number of healthy tubers, and had a highly significant effect on the number of tubers infested by pests. The combination of PGPR B. subtilis with a concentration of 2,5 ml L-1 with 25% of the recommended NPK dose (37.5 kg ha?¹) produced the highest tuber weight per plot and the highest RAE value (173,78%), while the combination of Bacillus subtilis and 100% NPK resulted in the highest number of healthy tubers that were not infested by Cylas formicarius. The use of PGPR allows a reduction of NPK fertilizer rates by 25% to 75% of the standard dose without decreasing yield.