Abstract

This study was conducted to determine the relationship between ambient temperature during growing season on tuber β-carotene content and yield of four orange-fleshed sweetpotato varieties; Orange Chingovwa, Olympia, Kokota and Zambezi. A split plot experiment design with the environment (main plot) and variety (subplots). The environments were: High-temperature site (HTS) (average temperature of 38.5°C) and moderate temperature site 1 (MTS 1) and moderate temperature site 2 (MTS 2) (average temperature 32.2 and 31.2°C, respectively). Results suggested that assimilate partitioning between below ground components (tubers) and above ground components (leaves and vines) were inversely related and influenced by ambient temperature during development. Low temperatures favoured tuber formation. The HTS had lower yield (0.97 ton ha-1) compared to the two moderate temperature sites that had tuber yield between 11.96 and 9.41 ton ha-1. The HTS at 7.23 mg/100 g had lower β-carotene contents compared to the MTS sites (≈15.5 mg/100 g). Zambezi and Orange Chingovwa had higher β-carotene content at 21.21 mg/100 g and (18.85 mg/100 g). Kokota had the least β-carotene (3.28 mg/100 g Vine Yield (VY) was significantly different for sites. HTS had the highest VY and leaf area (23.6 t/ha) while the two MTS had low VY of 8.7 and 12.9 t/ha.

Key words: Partitioning, tuber, leaf area, vine, yield.