Seleksi dan Mekanisme Toleransi Tanaman Tembakau (Nicotiana tabacum L.) terhadap Kekeringan

Abstract

The objectives of this experiment to determine level tolerance of thirty Nicotiana tabacum genotypes against drought stress under controlled conditions; to determine tolerance mechanism to drought; find out tolerant variety of tobacco. I To determine level tolerance of thirty Nicotiana tabacum genotypes against drought stress with two research. Selection based on relative growth, sensitivity index and water stata. Seedlings of thirty Nicotiana tabacum genotypes with different level of stress tolerance were grown in polybag containing potting medium. The first research was done at glass house of Rubber Research Station which took place for one months from June 12th to 24th 2005. The split plot design was used in experiment and three replications with 2 factors. The first factor was the watering every day and not watering again since 7 days after planting until 12 days after planting. Parameter in this experiment was water stata. The second research was done at glass house of Tobacco Research Station which took place for one months from Juni to July 2005. The split plot design was used in experiment and three replications with 2 factors. The plants were exposed to water stress by watering them every four days, eight days and twelve days. The control populations were watered everyday up to field capacity. Parameter in this experiment were relative growth dan sensitivity index. Results of the experiments indicated drought stress inhibit Nicotiana tabacum growth. During early growth, drought stress resulted in reduction of dry weight of root and shoot, reduced ratio dry weight of root and shoot, long root, plant height, and increased ratio long root-plant height. Sensitivity index based on dry weight of root and shoot, ratio dry weight of root and shoot, long root, plant height, and ratio long root-plant height be used as predictors for determining tolerance of tested Nicotiana tabacum genotype against drought stress. Selection of tolerance level drought of tobacco based on relative growth, sensitivity index and water stata that resulted K399, Connecticut x Local and PVH50 as tolerant genotypes and DB 101 and PVH 50 as sensitive genotypes. To determine tolerance mechanism to drought stress with two research. To determine tolerance mechanism to drought with physiology analisis and morphology analisis. The research was done at glass house of Tobacco Research Station which took place for one months from April 2006 up to May 2006. Physiology analisis were prolin, amino acid, total sugar, N, P, K, and Mg. The split plot design was used in experiment and three replications with 2 factors. Plant of six Nicotiana tabacum (K-399, Connecticut x Local, PVH-50, DB-101, VDM-2, Deli-4) varities were exposed to water stress by watering them every days and watering until 30 days after planting to analisis proline, amino acid, total sugars, N, P, K, and Mg. Proline accumulation was the major component contributing to solute . accumulation in leaf tissues of the drought tolerant tobacco. Amino acid and total sugars also increased as water stress developed, but their contribution to solute accumulation were relatively small. To determine tolerance mechanism to drought with morphology. Plant of six Nicotiana tabacum varities were exposed to water stress by watering them every days, 4 and 8 days to analisis morphology. Parameter in this experiment were thick of leaf, of cuticle, of upper epidermic, of lower epidermis, number of stomata, length of stomata, width of stomata, dry weight root, diameter of stem, width of the leaf and length of the root. Results of the experiments indicated that the drought tolerant varieties had thicker of leaf, of cuticle, of lower and upper epidermis, a less number of stomata, higher dry weight root, bigger diameter of stem, widthes leaf and longer root. To determine variety tobacco tolerant with two levels watering water in the field. The split plot design was used in experiment and three replications with 2 factors. The first factor was the watering every day and every 8 ciays. In a field experiment under stress conditions, K-399, Connecticut x Local, and PVH-50 with tolerant character demonstrated higher photosynthetic rate and quick growth. That showed from net assimilation rate, leaf area ratio, leaf area duration, leaf area index, and relative growth rate.