Vegetable Plant Part Relationships. III. Modification of Carrot (Daucus carota L.) Root and Shoot Weights by Gibberellic Acid and Daminozide

Abstract

Aqueous foliar sprays of N-dimethylaminosuccinamic acid (daminozide) at 2000 p.p.m. and gibberellic acid (GA) at 100 p.p.m. were applied 45, 59, 82 and 100 days after sowing to Chantenay carrots with population densities of 244, 495 and 883 plants m⁻². The plants were harvested on ten approximately weekly occasions; fresh weights were determined and d. wt estimates were obtained for the separated shoots (s) and roots (r). Allometric linear regressions of the logarithm of s on that of r at each harvest separately, clearly showed that GA always increased shoot: root ratio and reduced root yield (by approximately 35 per cent) but could sometimes also increase whole-plant weight. Daminozide increased root yield (by approximately 7 per cent from 80 tonnes ha⁻¹) and tended to have effects opposite to those of GA.