Response of kabuli chickpea to seed size and planting depth

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The use of small seed can reduce the production costs of kabuli chickpea (Cicer arietinum L.) 15 to 25% by reducing the amount of seed needed per unit area, but little is known about the effects of seed size on stand establishment, plant growth, and seed yield in semiarid environments. We conducted a field study in southwest Saskatchewan from 1998 to 2000 and determined the chickpea responses to seed size under different planting depths. Crops grown from small (7.1–9.0 mm) diameter seed required the same number of days to emerge (16.7 d) and mature (106 d) as those from large (9.1–11.0 mm) diameter seed. There were no differences in plant establishment, shoot dry weight, pod production, or seed yield between the two seed sizes when planted at a 50-mm depth. However, the small-seeded crop produced 7% lower plant stand, 4% lower seed yield, and 3% less seed 1799-mm diameter compared to the large-seeded crop when planted at a 100-mm depth (P < 0.05). Large-seed ed chickpea plants were 20 mm (4%) taller, and the height of the lowest pods from the soil surface was 11 to 13 mm (5%) higher than those from the small seed, suggesting an improvement of harvestability. In general, planting depth did not affect seedling emergence, shoot dry weight, or seed yield, but when small seed was used, chickpea sown at the 50-mm depth increased seed yield by 6% compared to that at the 100-mm depth. Kabuli chickpea produced an average of >20 pods plant-1, with 77% of them containing one seed per pod, 10% with two seeds per pod, and the remainder containing no seed; this ratio of pod fertility was independent of seed size or planting depth. Our results indicate that the use of small seed and shallow planting can reduce the production costs of chickpea by $31 to $52 ha-1 without a seed yield penalty. This level of saving in production far exceeds the otherwise increased value of $4 to $6 ha-1 with the use of large seed which produces a higher (3%) proportion of ≥ 9-mm diameter seed. Key words: Seedling emergence, seed mass, pod production, Cicer arietinum L.