Effectiveness of Plant Growth Promoting Rhizobacteria and NPK Inorganic Fertilizer on the Growth and Yield of Shallot Plants

Abstract

Using a combination of inorganic fertilizer and plant growth-promoting rhizobacteria is expected to reduce the residue of inorganic fertilizer use, improve soil fertility, and increase the growth and yield of shallot plants. This study aimed to determine the effectiveness of PGPR doses and their combination with inorganic fertilizer NPK in reducing the dosage of inorganic fertilizers on the growth and yield of shallot plants. This research was conducted in Maja Selatan Village, Maja District, Majalengka Regency, West Java Province. The research was carried out from September to November 2021. The materials used were: The red onion seeds of the Batu Ijo variety, Liquid PGPR containing Pseudomonas fluorescence: 9.3 x 108 CFU/ml and Rhizobium sp: 3.4 x 108 CFU/ml and also enriched with Azospirilum sp: 7.3 x 108 CFU/ml, Aspergillus niger: 3.4 x 107 CFU/ml and Trichoderma harzianum: 1.3 x 107 CFU/ml, for inorganic fertilizers use NPK Mutiara compound fertilizer. The research design used was a non-factorial Randomized Block Design (RAK), namely giving a combination of doses of NPK Mutiara fertilizer and PGPR with five treatments and five repetitions for each Treatment so that there were 25 planting holes with a distance of 15x15 cm, as follows: Treatment A = 100% Dose NPK compound fertilizer and 0% PGPR, Treatment B = Dosage of 75% NPK compound fertilizer and 25% PGPR, Treatment C = Dose of 50% NPK compound fertilizer and 50% PGPR, Treatment D = Dosage of 25% NPK compound fertilizer and 75% PGPR and Treatment E = Dosage of 0% NPK compound fertilizer and 100% PGPR. The data were analyzed using non-factorial RAK; if the Innova was found to have an effect, then it would be continued with a further test using LSI. Variables observed included plant height, Number of leaves, flowering time and tuber fresh weight. A regression analysis was carried out to determine the effectiveness of using PGPR. The results showed that all observational variables affected the administration of a combination of PGPR and inorganic fertilizers. The best combination was shown by the Treatment of 25% NPK and 75% PGPR on plant height, Number of leaves, flowering age and tuber fresh weight. The regression analysis results showed that increasing the dose of NPK correlated negatively, meaning that the higher the dose, the lower the yield. In contrast, the addition of PGPR was positively correlated, meaning that the higher the dose, the higher the shallot yield. The combination of NPK and PGPR fertilizers can reduce the use of inorganic fertilizers by up to 25%.