Cultivar responses to daylength and stem descent in aeroponic seed potato

Extending daylength during vegetative growth may improve aeroponic potato (Solanum tuberosum L.) growth but yield responses may depend on cultivar and canopy disturbance. Two cultivars, cvs. Atlantic Malang and Chipita, were grown under a natural 12 h day or a 16 h day created by 4 h supplemental LED lighting until 6 weeks after planting (WAP), combined with no stem descent or stem descent at 2 or 4 WAP. A split-plot randomised complete block design with five blocks was used; daylength was the main-plot factor and six cultivar-stem descent combinations were subplots. Data were analysed by split-plot ANOVA followed by Tukey's test and principal component analysis. At 6 WAP, 16 h increased canopy, root, stolon, and early tuber growth. In cv. Atlantic Malang without stem descent, 16 h increased final tuber weight per plant by 55%. In cv. Chipita, 16 h combined with stem descent at 4 WAP reduced final tuber number and weight by 71% and 59%, respectively. Cv. Chipita without stem descent or with descent at 2 WAP produced the greatest plot-level yields. Thus, daylength extension should be matched to cultivar and stem-descent timing.