Factors affecting seed shattering in Secale montanum and improvement of management in seed production sites.

Mountain Rye (Secale montanum Guss.) is a perennial grass, and desirable for grazing and forage production on pastures with average of precipitation 300 mm. Seed shattering is a major constrain for grain yield loss for growers in this species. The objective of this research were to study of genetic diversity, introduce factors affecting seed shattering for detecting Mountain Rye (Secale montanum Guss.) is a perennial grass, and desirable for grazing and forage production on pastures with average of precipitation 300 mm. Seed shattering is a major constrain for grain yield loss for growers in this species. The objective of this research were to study of genetic diversity, introduce factors affecting seed shattering for detecting tolerant populations and determine optimal seed harvest time for reducing seed shattering. This experiment was conducted on eight populations at Agricultural and Natural Resources Research Center of Razavi Khorassan during 2006 and 2007. The measurements were height plant, number of tiller, seed maturity and shattering at seed setting stage for 10 d intervals through five times. The spikes were studied for length, weight, internode length, and thickness of the rachilla, number of floret and seed length and width and 1000 seed weight. Also, seed germination, germination rate and seedling vigour for maturity stages including milk, dough, hard seed and harvest at dough stage plus windrowing for one month was measured. The result of phenological study showed that in all populations booting stage occurred on early May, anthesis on mid- May and then milky and dough from late May to mid-June and hard seed on late June. Seed Shading started after hard seed from top of inflorescence to bottom from late June for sensitive populations to mid-September for tolerant types. There is genetic variation for resistance to shatter with low frequency within populations. Therefore, populations were grouped into two groups including seed shattering and non-shattering by t test (P0.01). The comparison of susceptible with resistance to shatter revealed that many morphological factors effective for reducing seed shattering when spike length, spike weight, these ratio, spike internode length, and thickness of the rachilla were increased. Seed germination percentage 13.8, 38.2, 88.5, 93.8, and 98.4 and germination rate 22.3, 12.5, 51.9, 48.9, 60.8, and 63.3 were at milky, early dough, early hard seed, complete seed hard stages and windrowing, respectively. These results suggest that seed shattering in mountain ray was influenced by genetic factors. Maximal seed yield could be obtained with two strategies including seed harvest time at late dough stage (physiological maturity) plus windrowing for short time and breeding and selection in native populations for resistance to seed shatter for long time.