Effect of sowing season and seeding rate on the morphological traits and yields in pea cultivars of differing leaf types

The effects of three seeding rates (25, 50, and 100 seeds m(-2)) on several morphological traits, and dry matter, seed and protein yields were evaluated in two leafed, two semi-leafless and two tare-leaved pea (Pisum sativum L.) cultivars, with fall and spring sowing for 3 years. The experiments were conducted under rain-fed conditions in the Bursa Region of Turkey. Sowing season, seeding rate and cultivar type had a significant effect on most of the measured traits and the yield determinants. The actual number of seedlings per unit area varied greatly among varieties, sowing seasons and climatic conditions during emergence. Fall sowings had taller plants, and more pods and seeds per plant. The number of tillers per plant usually increased with declining seeding rate. Semi-leafless varieties had improved standing ability particularly at higher seeding rates and fall sowing conditions. The harvest index was higher for short strawed, tare-leaved varieties than both leafed and semi-leafless varieties. Harvest index was hardly affected by sowing season and seeding rate. In general, fall sowings and the highest seeding rate produced the highest dry matter, seed and protein yields in all pea cultivars. The yields of spring sowings varied greatly, primarily depending on the amount and distribution of the spring rainfall. In the wet spring of 1993, dry matter, seed and protein yields from spring sowing was higher than those of fall sowings for all varieties. The semi-leafless pea varieties, Countess and Niva, presented a clear advantage in the yield determinants under Bursa rain-fed conditions