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Salinity is a common abiotic stress that seriously negatively affects rice production in the world. The investigation was carried out at the Experimental Farm of El-Sirw Agricultural Research Station, Damietta governorate, Egypt to investigate the effect of soil salinity levels (6 and 11 dS m-1) on the morphological, leaf chemical constituents and yield traits and phenotypic and genotypic parameters of twelve rice genotypes (Giza 177, Giza 179, Giza 182, Egyptian Jasmine, GZ 10303, GZ 10305, IET 1444, GZ 10286, GZ 9399, GZ 9461, PLGF101 and Egyptian Hybrid 1) during 2014 and 2015 seasons. The obtained results could be outlined as following: 1- The high level of salinity negatively affected growth parameters (leaf area index, dry matter production and chlorophyll content) and yield related characteristics (heading date, plant height, number of tillers hill-1, number of panicles hill-1, panicle length, number of filled grains panicles-1, 1000-grain weight, grain yield, biological yield and harvest index) in both seasons. It was detected that increasing salinity sharply decreased rice grain and biological yields with reduction percent amounted to 43.66 and 33.81 % for grain yield and biological yield, respectively. On the other side, increasing salinity significantly increased proline content, Na+ % and Na+/ K+ ratio while decreased K+ % in rice leaf. 2- The different genotypes were significantly varied among each other in their growth and yield. Egyptian Hybrid 1 surpassed other tested genotypes in growth parameters, number of tillers and panicles hill-1, panicle length, number of filled grain panicle-1 and grain and biological yields ha-1 in both seasons as compared with the other rice genotypes. On the contrary, the rice genotype of Giza 179 had the lowest unfilled grains panicle-1. The salt tolerant rice genotypes (Egyptian Hybrid 1, Giza 179, GZ 9399, GZ 9461 and IET 1444) had higher proline content and potassium % and lower Na+ and Na+/ K+ ratio, while the sensitive salt rice genotypes showed opposite pattern. 3- The interaction between the tested rice genotypes and salinity levels was significant for studied traits in both seasons. In general, Egyptian Hybrid 1 genotype was superior for the most growth and yield traits when it was grown on medium or high salinity levels followed by GZ 9399 and GZ 9461 genotypes. However, PLGF 101 genotype had the worst performance followed by GZ 10303 and Giza 177 rice genotypes. It could be concluded that Egyptian Hybrid 1 genotype had considerable affinity for withstanding salinity stress to tested levels under the experimental salinity conditions. The maximum reduction for grain yield (65.94 and 66.83%) was produced by planting Giza 177 and Giza 182 genotypes in the first and second seasons, respectively. However, the lowest reductions (23.59 and 18.85%) were obtained by growing Egyptian Hybrid 1 and GZ 9399 in the first and second season, respectively. 4- The phenotypic coefficient of variability (PCV) was slightly higher than those of genotypic coefficient of variability (GCV) for all studied traits of the twelve rice genotypes grown under the salinity levels. The value of GCV % was varied from 21.44 to 41.93 but in PCV% ranged from 23.68 to 52.99 for grain yield. In most characteristics the increasing salinity level raised the contribution of environmental variability in phenotypic variability. High heritability (H2%) estimates in broad sense were detected for most studied traits. |
