Effects of foliar and tuber sprout suppressants on shelf life of ware potatoes under tropical ambient conditions

Authors: NYANKANGA, RICHARD - University Of Nairobi; MURIGI, WINNIE - University Of Nairobi; SHIBAIRO, SOLOMON - Kibabii University; Olanya, Modesto; Larkin, Robert - Bob

Submitted to: American Journal of Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/24/2018
Publication Date: 9/1/2018
Citation: Nyankanga, R.O., Murigi, W.W., Shibairo, S.I., Olanya, O.M., Larkin, R.P. 2018. Effects of foliar and tuber sprout suppressants on shelf life of ware potatoes under tropical ambient conditions. American Journal of Potato Research. Vol.95:539-549.

Interpretive Summary: Potato is an important food and cash crop for the resource-constrained farmers in the highland tropics. Long-term storage and shelf life of potato at post-harvest is important for food security. However, sprouting of tubers limits storability of potatoes under tropical ambient conditions, depending on the cultivar type and storage conditions. Due to limited data on sprout potential and storability of tubers of some tropical-adapted potato cultivars, we evaluated application of sprout suppressants for control of premature sprout development on tubers of cultivars Shangi , Asante and Kenya Mpya. Pre-harvest foliar applications of chemicals such as paclobutrazol (PBZ) and ethephon and post-harvest application of chloropropham (CIPC) and dimethylnaphthalene (DMN) on tubers of three potato cultivars were evaluated at ambient temperature of 23 C. Overall, pre-harvest foliar application of PBZ prolonged tuber dormancy by 21-31 days while simultaneously reducing tuber weight loss in tubers of the three cultivars. In contrast, ethylene releasing agent ethephon did not impact dormancy duration, sprouting percentage, and tuber weight loss. When CIPC was applied on tubers at post-harvest, excellent storage of tubers were observed for a period of up to six months with negligible weight loss and no sprout development. Due to the limitation of financial resources for cold storage of potato at the farm level in the highland tropics, prolong shelf life and reduced weight loss of potato tubers will greatly improve food security.

Technical Abstract: Potato (Solanum tuberosum) is an important source of dietary carbohydrate and cash income for farmers in the tropical highlands of Kenya. The feasibility for cold storage at the farm level is limited due to the high costs of maintaining such a facility and there is limited data on the long-term post-harvest storage and quality of tubers of tropical-adapted cultivars. Application of sprout suppressants to control premature sprouting of ware potato is an attractive proposition. We evaluated the efficacy of pre-harvest foliar applications of paclobutrazol (PBZ) and ethephon for sprout suppression on ware potato tubers of three cultivars in storage in comparison to post-harvest tuber applications of Isopropyl N-(3-chlorophenyl carbamate) chloropropham (CIPC), and 1, 4 dimethylnaphthalene (DMN). The tubers of potato cultivars had varying levels of dormancy. The tubers were stored at ambient temperature (23 deg C) and assessed for % sprouts, sprout length and tuber weight loss for 24 weeks. Paclobutrazol prolonged tuber dormancy period by 21-31 days and reduced the rate of tuber weight loss. Ethephon treatment had no significant (P>0.05) effect on dormancy, dormancy period, sprouting percentage and tuber weight loss. Potato tubers treated with CIPC had excellent storage of 6 months duration. Tuber response to DMN treatment differed among the three potato cultivars evaluated. The findings from this study imply that PBZ is effective in prolonging potato tuber dormancy for short-term basis at 23 deg C, while CIPC applied on tubers was effective for long term storage. Optimization of post-harvest potato storage can improve food security in the highland tropics.