Assessment of Critical Soil Water Potential for Emergence of Wheat, Chickpea and Linseed Seedlings in Relation to Water Stress in a Vertisol

摘要

Seedling emergence influences the initial plant population and hence the yield of any annual crop. Among the soil physical properties, soil water potential is the most critical factor influencing the seedling emergence. The narrow range of soil waterfor sowing operation and limited availability of irrigation water are the major constraints for seedling emergence and productivity of the dry season crops in Vertisols. A field experiment was carried out on a deep Vertisol at the Indian Institute of Soil Science, Bhopal to find out the critical soil water potential for the emergence of wheat, chickpea and linseed seedlings and to assess the amount of presowing irrigation required and the optimum time of sowing following the presowing irrigation for achieving the desired emergence of seedlings. Wheat, chickpea and linseed were sown after 1 to 9 days of drainage following application of six levels of presowing irrigation viz., 0, 2, 4, 6, 8, and 10 cm. The results showed that the critical matric potential for the initiation of emergence of wheat, chickpea and linseed was -72.60, -68.65 and -72.76 kPa, respectively and the corresponding critical volumetric water content at the time of sowing was 0.17, 0.19 and 0.18 cm~ cm~(-3), respectively. It was estimated that for achieving 50% emergence, wheat, chickpea and linseed might be sown respectively at 4, 3 and 1 days after drainage of 8 or 10 cm presowing irrigation. The emergence rate index decreased significantly with the increase of matric suction of the seed zone caused by application of less amount of presowing irrigation or delay in sowing after application of a given amount of presowing irrigation. The logistic growth model successfully predicted the relative emergence of wheat, chickpea and linseed.