Kajian Bakteri Bacillus subtilis dan Toleransi Kekeringan pada Padi Gogo (Oryza sativa L.) Pendekatan pada Pemahaman Mekanisme dan Interaksi

Abstract

Rice is the main staple crop providing carbohydrates for the majority of the world's population. A primary challenge in the cultivation of upland rice is drought stress. One promising technology for mitigating drought stress is the use of B. subtilis. The objective of this study is to examine the mechanisms and interactions of two upland rice varieties, Sigambiri Merah and Inpago 13 Fortiz, under drought stress conditions and different B. subtilis application methods. The experiment was conducted in the Greenhouse of the Faculty of Agriculture, Universitas Sumatera Utara, using a Randomized Complete Block Design with three factors and three replications. The first factor was the rice varieties: Sigambiri Merah (local superior) and Inpago 13 Fortiz (superior). The second factor was the rhizosphere microbial application technique: no application, application to seeds, and application at 3 weeks after planting (WAP). The third factor was soil moisture content: 40%, 60%, and 80% field capacity. The results showed significant differences between Sigambiri Merah and Inpago 13 Fortiz in average plant height, leaf area, proline content, H2O2 content, with higher empty grain percentage in Sigambiri Merah. Meanwhile, Inpago 13 Fortiz showed higher values in leaf and tiller number, shoot and root fresh weight, root length, stomata number and width, POD and SOD content, total sugar, panicle length and number, filled grain per clump, and filled grain weight. Application of B. subtilis at 3 WAP significantly affected the morphological traits (plant height, leaf number, total tiller number, shoot and root fresh weight, shoot and root dry weight, shoot-root ratio, root length, root volume, leaf area), anatomical traits (stomata width, leaf bulliform cell length), physiological traits (chlorophyll a, b, and total), and biochemical traits (H2O2, POD enzyme, proline, total sugar content) of upland rice. Drought stress treatment through soil moisture reduction significantly influenced changes in morphological characteristics (plant height, leaf number, tiller number, shoot and root fresh and dry weight, shoot-root ratio), anatomical characteristics (stomata number and width, leaf bulliform cell length), physiological characteristics (chlorophyll content), and biochemical characteristics (increased hydrogen peroxide content, POD enzyme, proline content, total sugar) and production traits (panicle number and length, filled grain number). The interaction of the three factors significantly affects chlorophyll content, proline, and the number of panicles, helping the plants to cope with stress and increase productivity.