Improvement of Sugarcane Seeds Drought Stress Tolerance by Invigoration using of Trichoderma as Bio-Primer

Sugarcane growth consists of germination, budding, vegetative growth, and maturity phases. Determination of the next phase is determined by the germination phase which is influenced by seed quality, glucose, nitrogen, water, seed treatment [1]. The problem in the field, especially in West Borneo, availability of superior sugarcane planting material was limited and forcing farmers to buy seeds from overseas. As that result, the seeds fall on deteriorate and the quality of the seeds decreases due to the delivery process which takes several days. In the shipping process, especially in the tropics, temperature fluctuations will occur, with the recalcitrant nature of sugarcane seeds, the seeds cannot withstand storage conditions at 10°C and above 35°C so they will be through chilling injury and reduce their viability [2]. Seeds that have low quality can reduce their vigor and viability, which in turn reduces plant productivity. In West Borneo during the long dry season experienced drought conditions so that water supply was limited. Though sugarcane seeds require a lot of water, one of which is during the germination phase. Drought stress in the germination phase affects the quality, growth in the next phase. Each sugarcane clone produce a different expression in response to drought stress. Research by [3] showed that the PS881 clone was able to adapt to conditions drought stress in the early growth phase in unfavorable seed conditions experiencing storage. The main key in increasing crop production is healthy seeds that have viability and vigor of more than 85%. According to [4] that the highest growth and yield was produced by sugarcane seeds that were not stored.

The existence of the above problems, one of the strategies to solve them can be through biopriming techniques using biological agents Trichoderma spp by utilizing the secondary metabolites produced. This technique is often used in food crops, but not many have applied this technique to plantation seeds, especially sugarcane. Biopriming is the immersion of seeds in a suspension of biological agents so as to activate signals to maintain stress and increase vigor [5]. Trichoderma was also able to increase resistance to abiotic stresses, one of which is drought, nutrient absorption, and increasing root growth and development. Trichoderma produces phytohormones such as Indole Acetic Acid (IAA) which is stimulating root and shoot growth [6]. Trichoderma priming technique gave a significant increase in the content of phenol, proline, stomata conductance, photosynthesis, chlorophyll content of wheat plants under drought stress conditions [7]. This technique had also been increasing the size of the seed germination, vigor index and root-shoot growth [6]. Biopriming of seeds using Trichoderma harzianum for 4 hours at 40% concentration resulted in a germination rate of 78%, an index of germination speed of 9.2 in chickpeas [8]. Priming for 24 hours increased vigor, average germination time and increased okra yield up to 55% [9]. In another study, Azozpirillum 20% biopriming treatment for 12 hours was the best treatment for maize germination and vigor [10]. Research on the use of secondary metabolites of Trichoderma in the invigoration of drought stress tolerant sugarcane clones using biopriming technique can be used to improve the quality of sugarcane seeds after experiencing setbacks due to storage and increasing plant resistance in drought stress conditions and can be further developed in sugarcane cultivation in suboptimal land. This study aimed to analyze the effect of Trichoderma biopriming on drought stress sugarcane clone germination, determine the appropriate duration of Trichoderma biopriming for drought stress sugarcane clone germination, determine drought stress sugarcane seed vigor index with Trichoderma biopriming application.