Phosphorus uptake and its utilization by onion varieties at different stages of growth

摘要

Onion (Allium cepa L.) is a major source of foreign exchange-earner amongst vegetables in the country. Generally, it requires a higher level of available P and K in the soil to achieve more yield than other temperate vegetables (Greenwood et al., 3). As onion has shallow root system, low root densities and lacks root hairs, it needs a high concentration of P in soil solution to drive diffusion to root surface at a rate sufficient to satisfy the potential demand (Brewster, 1). Phosphorus fertilization has received prime attention in recent years because of its low utilization by most of the crops (Raju et al., 8). The major problem associated with low utilization is high rate of P fixation. This has resulted in wide disparity among P recommendations ranging from 26 to 113 kg/ha from field experiments. However, little information is available till date with regards to actual release of P in soil, and its subsequent uptake and utilization by crop for sustained higher production of quality bulbs. Therefore, present study was designed to understand the effect of P on yield and the pattern of its uptake and utilization at different stages of crop growth.