Distribution of root activity in young 'Alphonso' mango (Mangifera indica) trees as influenced by season and growth.
Kotur S. C., Iyengar B. R., Shivananda T. N.
Author Affiliation: Isotope Laboratory, Indian Institute of Horticultural Research, Bangalore, Karnataka 560 089, India.
Indian Journal of Agricultural Sciences 67 : 113-116
Abstract : In studies carried out at Bangalore, India, during 1992-93, spatial distribution of root activity was studied using the 32P soil injection technique in 8-year-old trees of cv. Alphonso budded on Bangalora rootstocks grown on a loamy sand (Typic Haplustalf) belonging to the Thyamagondlu series. During the late rainy season, most of the active roots (80%) were confined to a 100-cm radial distance, with 30% at 50-cm. A substantial percentage of the active roots was found at depths of 20 and 60 cm (41 and 46% respectively), whereas only 12% occurred at 40 cm. During winter, the active roots were uniformly distributed (80-85%) up to a 100-cm radial distance; root activity increased with depth. In summer, only 20 and 28% active roots were found at 50- and 100-cm radial distances, respectively, whereas 52% active roots were found at 150 cm. Root activity decreased with depth (50, 31 and 19% at 20, 40 and 60 cm, respectively). There was variation in the distribution of active roots with season, indicating that high root activity coincided with high volumetric moisture content in the soil profile, particularly in the top 15-cm layer. The high intensity of root activity preceded a period of high shoot and floral growth observed in winter. In summer, root activity was very low. The presence of significant root activity (40-70%) below a 20-cm depth despite a clayey texture, hard to very hard, dry consistency, and blocky structure was probably due to the presence of adequate moisture at these depths.