Physiological characteristics of IRR 400 series rubber clones (Hevea brasiliensis Muell. Arg.) under drought stress

Abstract

Background: Drought stress is one of the main causes of plant death. Strategies for plant survival include triggering of specific signaling pathways and tolerance mechanisms. Rubber plantations have many uses, including in forest revitalization and as foreign exchange sources, job sources, and as an alternative source for building materials and furniture. The rubber plant’s response to drought stress is a complex biological process. Planting tolerant rubber clone in drought prone areas would be more appropriate. The present study is aimed to identify drought tolerant traits in order to select drought-tolerant clones at juvenile stage itself. Methods: The first factor examined for this research was the clones (IRR 425, IRR 428, IRR 429, IRR 434, IRR 440, RRIC 100, and BPM 24), with water content (30%, 60%, and 90%) as the second factor studied. The study was arranged on a factorial randomized block design and repeated three times. Characteristics observed included total sugar (µM), proline (mg/L), chlorophyll a, b, total (µg/mL), hydrogen peroxidase (µmol/g), ascorbate peroxidase (unit/mg), superoxide dismutase (unit/mg), and peroxide dismutase (unit/mg). Results: The tolerance ability of the IRR 400 series rubber clones to drought stress was determined by observing the concentrations of total sugar and proline, which were higher when the plant was treated with a lower water content. The selected clones tolerant to drought stress were RR 425 and IR 434 with high total sugar and proline. Other characteristics, namely chlorophyll a, b, and total, as well as hydrogen peroxidase, ascorbate peroxidase, superoxide dismutase, and peroxide dismutase, cannot be used as selection characteristics for this study. Conclusions: This drought study of IRR 400 clones with varying water content percentages illustrated that the total sugar and proline characteristics could be used to distinguish tolerance levels.