| dc.description.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. | en_US |
