Morphological changes and yield enhancement of Russet Burbank potatoes by AC 243,654

The nitroguanidines are a new family of plant growth regulators with cytokinin-like activity. AC 243,654, l-(m)-methoxybenzyl)-3-nitroguanidine, is a member of this family, and has caused morphological and yield changes on several crops. Greenhouse-grown potatoes (Solanum tuberosum L.), cultivar Russet Burbank were exposed at 15 days after emergence (DAE) to AC 243,654 at 0.5 and 1 kg/ha. The effects of AC 243,654 on plant growth and tuber yields were determined at 7, 14, 28, 42, 56, and 70 days after treatment (DAT). At 14 to 42 DAT, AC 243,654 increased the number of branches. Stolon length was increased at 7 and 14 DAT, and root length was decreased at 7 DAT. Stem length was not affected. Plant weight was higher in treated plants than in checks at 14 DAT but not at 28 DAT. At 42 DAT, the check weight was decreasing while the weight of the treated plants was maintained. The slower weight loss in treated plants is attributed to the anti-senescence effect of AC 243,654. Treated plants had greater tuber yield and number than the checks at tuber initiation, 7 DAT. From 14 DAT to the final harvest at 70 DAT, the treated plants produced higher yields than the checks of tubers over 25.4 mm. This resulted in higher total yields at 42, 56 and 70 DAT, but not at 14 and 28 DAT due to the proportionately lower yield of tubers less than 25.4 mm