The effect of MCPA and paclobutrazol on flowering, berry set, biomass production, tuber yield and quality of potato

Abstract

The effects of MCPA and paclobutrazol on potato (Solanum tuberosum L.) flowering, berry formation, dry matter production and allocation, tuber yield and quality were investigated under greenhouse and field conditions at the Experimental Farm of the University of Pretoria. Both MCPA and paclobutrazol were applied during early and full bud stage at rates of 0, 5.6,11.2, and 16.9 mg a.i. plant⁻¹. Regardless of rates and stages of application MCPA and paclobutrazol prevented flowering and completely inhibited berry set. MCPA did not affect the number, yield, specific gravity and dry matter content of the tubers. Without affecting the number of tubers initiated, paclobutrazol increased tuber yield, specific gravity and dry matter content. MCPA decreased assimilate partitioning to the stems. Paclobutrazol treatment at early flower bud stage resulted in higher tuber yield than spraying during late flower bud stage. Paclobutrazol decreased assimilate partitioning to the leaves, stems, and roots while it increased partitioning to the tubers. A single foliar spray of MCPA or paclobutrazol at the early flower bud stage at a rate of 250g a.i. ha⁻¹ reduced flower formation and completely inhibited berry set.