Root activity distribution studies in citrus, grape, mango and guava using isotopic techniques.
Kotur S. C., Murthy S. V. K.
Author Affiliation: Indian Institute of Horticultural Research, Bangalore 560089, India.
Karnataka Journal of Agricultural Sciences 11 : 651-657
Abstract : Soil injection of carrier-free 32P was used to study root activity distribution in fruit crops. All 4 citrus crops (oranges, 2 types of mandarin, and limes) were shallow-rooted while grape (cultivars Anab-e-Shahi and Thompson Seedless), mango (cv. Alphonso) and guava (cv. Arka Mridula) were deep-rooted. The spread of active roots was uniform during north-east monsoon period due to uniformly moist soil mantle. During summer, the active roots moved toward the soil surface and away from the trunk toward the periphery of the drip-circle. The intensity of root activity was highest during northeast monsoon due to high volumetric soil moisture, and decreased during winter as the rains receded. Least activity was observed during summer due to depletion of soil moisture. Generally the period of high root activity alternated with that of shoot growth except in guava in which both high root activity and shoot activity coincided. These results can be used to predict the time and placement of fertilizer during the year to achieve the best fertilizer use efficiency.