Optimum plant population density for chickpea and dry pea in a semiarid environment

Abstract

Chickpea (Cicer arietinum L.), an annual grain legume, is being broadly included in cereal-based cropping systems throughout the semiarid Canadian prairies, but information on optimum plant population density (PPD) has not been developed for this region. This study, which was conducted from 1998 to 2000 in southwestern Saskatchewan, determined the effect of PPD on field emergence, seed yield and quality, and harvestability of kabuli and desi chickpea compared with dry pea (Pisum sativum L.). Seed yields of all legumes increased with increasing PPD when the crops were grown on conventional summerfallow. The PPD that produced the highest seed yields ranged from 40 to 45 plants m-2 for kabuli chickpea, from 45 to 50 plants m-2 for desi chickpea, and from 75 to 80 plants m-2 for dry pea. When the legumes were grown on wheat stubble, the PPD that gained optimum seed yield ranged from 35 to 40 plants m-2 for kabuli chickpea, from 40 to 45 plants m-2 for desi chickpea, and from 65 to 70 plants m-2 for dry pea. The proportion of large-sized (>9-mm diameter) seed in the harvested seed was >70% when the kabuli chickpea was grown on summerfallow regardless of PPD, whereas the large-seed proportion decreased with increasing PPD when the crop was grown on wheat stubble. Increases in PPD advanced plant maturity by 1.5 to 3.0 d and increased the height of the lowest pods from the soil surface by 1.4 to 2.0 cm (or 5 to 10%), with desi chickpea receiving the greatest benefits from increased PPD. The percentage of plants established from viable seeds per unit area decreased substantially as PPD increased, with kabuli chickpea emergence decreasing from 90% at PPD = 20 plants m-2 to 72% at PPD = 50 plants m-2, from 81 to 69% for desi type, and from 83 to 59% for dry pea . The reason for the low field emergence with increased PPD is unknown, but methods which lead to improved field emergence represent a great opportunity to increase seed yield and reduce production costs for both chickpea and dry pea in this semiarid region. Key words: seed size, Cicer arietinum, Pisum sativum, seeding rate, summerfallow