Chemical Seed Priming as an Efficient Approach for Developing Cold Tolerance in Jatropha

Abstract

Jatropha (Jatropha curcas L.), an important biofuel plant, is highly sensitive to cold stress, which has limited its distribution to subtropical arid regions. Seed priming technique was applied to Jatropha strain DARL-2 to improve seed germination and survival on subsequent exposure of the seedlings to cold (4 °C) stress for 10 days. Jatropha seeds were treated with various priming agents for 24 h, and the priming agents' effect was assessed on germination as well as on survival upon exposure of the seedlings to cold. Seed priming significantly (P ≤ 0.05) improved germination percentage and opening of cotyledonary leaves. Similarly, germination rate, expressed as Timson's index and the rate of emergence of true leaves, was significantly higher in all the priming treatments than those for unsoaked control (US). On exposure to cold 65 days after sowing (DAS), the plants grown from primed seeds exhibited significantly (P ≤ 0.05) lower leaf senescence, which was associated with significantly higher (62.0–66.3%) relative water content (RWC) than the plants from unsoaked seeds (47.8%). Also in response to cold stress, the membrane damage (MD) was significantly higher in the control (72.4%) than in the plants grown from primed seeds (37.6–49.4%), except thiourea (TU) treatment. Thus, the results indicate that chemical seed priming could be an effective pre-germination strategy for successful cultivation of Jatropha in cold, arid regions.

Keywords:

• Jatropha
• germination
• Timson's index
• water relations
• membrane damage
• cold tolerance

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