The Effects of Fertilizer Rates on Dry Weight, Morphology, Length and Activity in Potato Root

Abstract

Knowledge of the fertilizer effect on the roots of potato plants is surprisingly limited and not definitive. In order to obtain more detailed information, root dry weight (DW), root length, root morphology and root activity were investigated under field conditions at different fertilizer rates (0, 75, 150 and 300 kg/ha in each component of N, P₂O₅ and K₂O). The roots were sampled 28 days and 56 days after sprouting with a monolith of 5 cm in width, 30 cm in length and 30 cm in depth. Root activity was identified by root respiration rate per unit root length (ULRR). The ratios of lateral root length to total (nodal+lateral) root length and of root length to root DW were relatively constant regardless of the fertilizer rates. The root length showed similar changes such as root DW, depending on the fertilizer rates. The increases of root DW and root length were suspended and the decay of the roots started earlier at the lower fertilized plot. In addition, ULRR increased significantly with the increase of the fertilizer rates at both sampling times. Its differences were much larger at 56 Days. These results suggested that an increase of the fertilizer rates would result in the increased nutrient absorption ability of the roots especially after the initial flowering stage, depending mostly on the differences in root activity per unit root mass.