Rooting patterns of four crop legumes in response to seed-placement depths in the dry season
Buakum, B., Limpinuntana, V., Vorasoot, N., Pannangpetch, K. and Bell, R.W. (2012) Rooting patterns of four crop legumes in response to seed-placement depths in the dry season. Acta Agriculturae Scandinavica, Section B - Soil & Plant Science, 62 (1). pp. 35-48.
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On sandy paddy fields, key factors for successful crops in the dry season without irrigation are a shallow water table and practices such as deep seed-placement but only some legume species are adapted to such conditions. To understand the adaptation of legume species to deep seed-placement over shallow water tables, we studied their rooting patterns on two sandy soils. Cowpea (Vigna unguiculata), mungbean (Vigna radiata), peanut (Arachis hypogaea) and soybean (Glycine max) seeds were sown shallow (similar to 5 cm) or deep (similar to 15 cm) in deep sandy soils after harvesting rice in two shallow water table locations in north-east Thailand. The legumes depended mainly on capillary water rising from the water table and none experienced water deficit throughout the growing season. Generally, deeper seed-placement decreased overall root dry weight, but it increased the root surface area to weight ratio. Deep seed-placement promoted a greater fraction of root growth into the subsoil for cowpea (86-99% of total root length), mungbean (61-93% of total root length) and peanut (78-98% of total root length) where the soil contained more water throughout the growing season. Moreover, deep seed-placement at the site with the lower water table promoted deeper penetration of roots of cowpea (similar to 20 cm deeper), mungbean (similar to 20-40 cm deeper) and peanut (similar to 20-40 cm deeper) which improved water access, especially late during the growing season when topsoils dried to close to wilting point. Unlike other species, the soybean rooting pattern did not respond much to seed-placement depths, or soil moisture.
|Publication Type:||Journal Article|
|Publisher:||Taylor & Francis|
|Copyright:||© 2012 Taylor & Francis|
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