[Evaluation of some Barley (HordeumvulgareL.) Genotypes for lodging resistance under irrigation conditions]

The study was carried out in the laboratories of field crop department and biotechnology department for the lab work, and Abi Jarash farm in the faculty of agriculture, Damascus university for the field work. The research work was conducted during the growing season 2009-2010, 2010-2011. Ten varieties of barley were used, according to randomized complete block design (RCBD), with three replication, in order to evaluate some of the varieties for lodging resistance based on some morphological, anatomical and molecular indicators, and to study the most important criteria and associated indicators and to introduce it into breeding programs, with the possibility of identifying some of the genetic sites responsible for the lodging resistance. We have studied many of the field traits associated directly and indirectly with the lodging resistance of the studied varieties and we have found that plant height, stem length, wall thickness, stem diameter, the length of the second internode, and the length of the main spike, are a key indicators associated with lodging resistance. The other traits such as the numbers of total and productive tillers, the number of internodes, the total weight of the plant, main spike weight, and the weight of secondary spikes. In addition to the characteristics affecting the grain yield, such as: total number of grains per plant, total weight of grains per plant, thousand grain weight, harvest index which are indicators that indirectly influence on the lodging phenomenon. In addition to that we have studied some laboratory characteristics such as the number, length and weight of roots, length and weight of the embryonic peduncle. The results of statistical analysis, showed that the Arabi abiad surpassed other varieties in root weight (0.026 g) and the weight of embryonic peduncle (0.073 g), while the Fourat6 recorded the lowest values of root weight and the weight of embryonic peduncle (0.010 g, 0.013 g, respectively). The improved Arabi abiad recorded the largest value of the embryonic peduncle length (4.53 cm), which allow increasing the depth of sowing and getting strong seedlings with good establishment capacity, which increases their ability to resist root lodging. While Fourat7 recorded the lowest values of the length of embryonic peduncle (3.15 cm). The results showed that lodging resistance in the barley plant was affected by the anatomical characteristics of stem, especially stem diameter and thickness, Fourat4 surpassed other varieties in plant height (88.4 cm), stem length (83.6 cm), the length of the second internode (12.09 cm), stem thickness (41.42 µm), and total stem diameter (387.4 µm). While Arabi asuad recorded the lowest value of the length of the second internode (9.94 cm), and stem thickness (34.50 µm) and diameter (257.2 µm). The length of the second internode is important trait for lodging resistance, whenever the second internode more shorter the variety will be more resistant to lodging. Through our study we noticed that the varieties Arabi asuad, Fourat2 and Fourat5 recorded the lowest value of the length of the second internode (9.94, 10.03 and 10.14 cm, respectively) compared with the rest of the varieties. The results showed that the total plant weight and the weight of main spike and weight of secondary spikes influenced negatively on lodging resistance, when the total plant weight and total weight of spikes per plant will increase its suseptibility to lodging, and the varieties Arabi asuad and Fourat3 recorded the lowest plant weight (10.13 and 12.37 g, respectively). It was noticed a strong and significant positive correlation between plant length and the stem length (r= -0.933**), and strong and significant positive correlation between the numbers of total tiller and both the plant weight (r =0.789**) and the number of productive tiller (r= 0.933**). Also the correlation was negative and significant between the length of second internode and wall thickness (r= -0.305**). The genetic study indicated to the effectiveness of all used primers and their ability to give polymorphism among varieties, and primers gave a total of 11 allele with a polymorphic percentage of 100%. The number of bands for each primer varied from minimum 1 bands for the primer (Bmac0067) to maximum 4 bands for the primer (Bmag0125), in average of 2.2 bands for each primer, cluster analysis and Dendrogram showed the highest degree of genetic relationship was between variety Fourat5 and variety Fourat7 (0.0371), while the lowest degree of genetic relationship was observed between variety Fourat5 and variety Fourat6 (0.3339), which indicates vast genetic diversity among them. The genetic study also demonstrated that the varieties Fourat6, Fourat2, Arabi abiad, possess the largest number of genetic sites responsible for the lodging phenomenon in comparison with the rest of the varieties, and this is consistent with the results of morphological and anatomical study, i.e, they are the most resistant varieties to the lodging phenomenon.