Evaluation of growth ability in drought tolerant crops

Identification and classification of legumes and grasses whoes collected from different area of Iran can facilitate accessing to tolerant genes. Therefore, acceleration of tolerant gene transfers to other species and promotion of plant breeding could be possible. The results are summarized. During the experiment from 104 sites located in 14 provinces, 110 plant species from 24 genuses of grasses and 14 geneses of legumes where collect and identified. This experiment showed that most of grasses either salt or drought tolerant species are distributed in Khorasan while that of Ardabil and Qazvin have the lowest distribution. Legumes mostly scattered in western and southwestern provinces. In other to identify tolerant spices to drought stress, 68 grass accessions including 22 species from 8 grass genus (Dactylis, Festuca, Hordeum, Bromus, Secale, Aegilops, Agropyron and Elymus) together with 35 legume accessions from 5 legume genus with 8 species (Medicago, Trifolium, Lotus, Sophora, Medilotus) were plant in plastic pots covered by nylon sheaths. Irrigation levels were FC, 75% FC, 50%FC and 25%FC. Results showed that in grasses most of measured characteristics highly affected by drought stress and within attributes, radicle and seedling length highly reduced by increasing drought stress level (57.9% and 46% respectively). Even more severe reduction was observed in legumes. While seedling length reduced by 89.9% radicle length decreased by about 66%. This investigation showed that among grasses, Bromus tomentellus and Secale montanum were the most tolerant species, while that of Festuca arundinaceae, Dactylis glomerate and Fstuca ovina were that most sensitive species. In addition to that, among legumes Medicago laciniata was that most tolerant species and Melilotus officinalis was the most sensitive species. To determine the growth responses of 36 populations of grasses from 15 species of seven genera of forage species to water stress. The grasses were collected from different dry area of Iran. The seeds of population were planted in well-watered soil for 90 day at tellring stage in green house. Effects with hot day water for 50 days to reach wilting point, followed by 35 days rewatering on leaf relative water content, root and shoot dry weight and ١٤١ root length were studies. Results showed that all measurement except root dry weight and root length were significantly affected by the treatment (P 0.05). Water stress decreased root and shoot dry weight (about 50%), whereas, root to shoot ratio and recovery dry matter increased 22 and 43% in compared to the control, respectively. Our result showed that Elymus elongatum had a high yield potential under both well water and stress condition it can be concluded that root extension and carbohydrate storage associated with greater drought tolerance and recovery yield at early stages of growth. Effect of irrigation gradient on forage yield under field conditions. From June to September , a line source (LS) irrigation system was used for 2 year to evaluate forage yield and visual characteristics under four water levels (WL). Amounts of water received by the plots for WL1 (nearest to LS) through WL4 (Farthest from LS) were 345, 262, 154,and 78 mm per year, respectively. Significant difference were detected among the grasses for dry matter yield (DMY) per year and in the combined analysis across years. Annual DMY of the grasses averaged for WL1 and WL4 respectively, were 3.61 and 1g / plant in first year and 3.53 and 0.8 g /plant in the second year. Generally, on increase in DMY at the summer followed by a reduction in cool season and vice versa was observed. Whereas. Some of species such as Festuca ovina had no variation across 2- year. Both Elymus elongatum and Bromus confinis also showed high yield potential across through WLS. These results indicated that line source irrigation system could be useful too for evaluating drought tolerance of forage grasses