EFFECT OF SEED SIZE AND PLANT SPACING ON GROWTH, FORAGE AND SEED YIELD OF GRASS PEA (LATHYRUS SATIVUS L.)

This field study was conducted in the agricultural winter season of 2019-2020 in two sites, the first one was in Tobzawa village/Bashiqa sub-district, about 25 km east of the city Mosul and the second one was in Al-Thaljah village/Hmaidat sub-district, about 20 km west of Mosul. The research aims at studying the effect of three plant spacing distances among rows (10, 20 and 30 cm) with three seed sizes (small, non-graded and large) on the characteristics of growth, forage and seed yield of grass pea using the split plot system with a Randomized Complete Block Design (RCBD) with three replications. The results showed that the plant height and leaf rate characteristics were significantly affected by the plant spacing in the two study sites, Tobzawa and Al-Thalja. The 10 cm-plant spacing between the rows provided the highest average for dry forage yield mounted to 2.34 and 0.94 tons at both sites Tobzawa and Al-Thaljah, respectively. The seed yield and its components characteristics were not significantly affected by the plant spacing with the exception of the number of pods/plant at Tobzawa site and the seed yield at Al-Thaljah site. The results showed significant differences among the plant sizes in the characteristic of the plant height at the both study sites, whereas the two characteristics of the number of branches/plant and dry forage yield were not significantly affected by the seed size in Tobzawa and Al-Thalja sites. The weight of one thousand seeds and the total seed yield characteristics were also significantly affected by the seed size in Al-Thaljah site only, where the large seeds provided the highest seed yield of 0.47 tons/ha at Al-Thalja site. The overlap between the plant spacing and the seed size significantly affected the characteristics of plant height and leaf ratio on the one hand and the number of seeds/pod and weight of 1000 seeds, on the other hand, in the two sites of the study.