Spike morphological characteristics and factors affecting seed shattering in Mountain Rye (Secale montanum Guss.)

Mountain Rye (Secale montanum Guss.) is a perennial grass, and attractive for grazing and forage production on pastures, with average precipitation of 300 mm per year. Seed shattering is a major constrain for grain yield loss for growers of the species. The objectives of the research were to study genetic diversity and introduce factors affecting seed shattering for detecting seed shattering resistant plant populations. The experiment was conducted on eight populations at experimental field of Agricultural and Natural Resources Research Center of Khorasan Razavi, Iran, during 2006 and 2007. The measurements were done on seed maturity and shattering at seed setting stage by 10-days intervals for five times and the spike characteristics, including length, weight, internode length, and thickness of the rachilla, number of floret, seed length and width, and 1000 seed weight. Results showed that seeds were fully matured by late June and seed shading started after June from top of inflorescence to bottom from late June for sensitive populations to mid-September for seed shattering resistant types. There was genetic variation for shattering resistance with low frequency within the populations. Therefore, populations were divided into two groups including seed shattering and non-shattering by t-test (P<0.01). Also, comparison of the spike characteristics revealed that the most important reducing factors of seed shattering were spike weight, spike length, their ratio, seed weight on spike, and spike internodes length with increments of 75, 19, 31, 31, and 5.1%, respectively, comparing to the seed shattering populations. The results suggest that seed shattering in mountain ray was influenced by genetic factors and native seed shattering resistant populations can be found in the country.