Evaluation of yield and agronomical traits of foxtail millet (Setaria italica (L.) Beauv.)genotypes under salinity stress andintroducingthe best tolerance index to salinity

Introduction Salinity is one of the most important tensions in global agricultural production. About 20% of the irrigated lands are facing salinity problems in arid and semi-arid regions of the world, and salinity in these areas is increasing. In Iran, the salinity is about 44.5 million hectares, which has varying degrees of salinity and alkalinity (Banaei, et al., 2005). Selection of salt tolerant genotypes in farmer conditions is a practical and dealing ways in using saline water and soil. Millet cultivation in Iran has a long history and according to the short growth period, is able to feed forage in conditions where other sources of forage are not available. The cultivated area in Iran is about 10,000 hectares (Aaron, 2006). According to recent studies, it is possible to develop plant cultivation in all regions of the country. The area under cultivation of this plant in the south khorassan province is about 1000 hectares and the cultivation of this plant has long been rooted in the culture of farmers in this area (Bina, 1993). According to the adaptability of this plant to unfavorable environmental conditions, soil poverty and environmental stresses that are characteristic of arid and semi-arid regions such as South Khorasan. One of the easiest ways to identify and selection of resistant genotypes is explosion to stress and selection the genotypes that tolerate these conditions better than the others. Materials and Methods In order to evaluation of salt tolerance in foxtail millet genotypes, two separate experiment with 15 genotypes in saline and none-saline conditions arranged in randomized complete block design with three replications conducted in two years of 2012 and 2013 at the Research and Education Center of Southern Khorasan. Combined analysis of variance showed that salt stress lead to a significant reductions in days to heading, days to maturity, plant height, panicule length, number of panicule per plant and thousand seed weight.In the end, after determining the grain and forage yield in stress and non stress conditions, MP, GMP, TOL, HARM, STI and SSI indices were calculated and using SAS software, correlation between the indices with grain yield and The dry forage was examined and using the SigmaPlot software, the three-dimensional distribution chart of each sample was plotted in A, B, C, and D ranges. Results and discussion Millet seed yield and dry forage yield in saline condition decrease about 40 and 38 percent, respectively. Genotypes number 15-118, 15-24 and 15-120 with averages of 3827.8, 3805.1 and 3803.2 kg/ha had the highest and number 15-80 with 1977.2 kg/ha had the lowest two year averages of yield, respectively. Results of correlation of seed yield and dry forage yield of millet genotypes in saline and none-saline conditions with tolerance and sensitivity indices revealed that STI, MP and GMP are the best indices for selection and recognition of salt tolerance genotypes of foxtail millet. Genotypes numbers of 15-24, 15-76, 15-118 and 15-120 indentified as the most tolerant genotypes to salinity stress on the basis of 3D scattering graph.