Comparative Effects of Foliar Application of Gibberellic Acid and Benzylaminopurine on Seed Potato Tuber Sprouting and Yield of Resultant Plants

Abstract

Seed potato tubers planted immediately after harvest is characterized by delayed plant emergence, poor establishment and low yields. Gibberellic acid (GA) and Benzylaminopurine (BA) or their combinations cause dormancy breakage though little information is available on their combined application to dormancy termination. The effects of foliar application of GA and BA on potato tuber sprouting and subsequent yield were studied. Three potato varieties with different tuber dormancy period; ‘Asante’ (short dormancy), Dutch Robyjn (medium dormancy) and ‘Kenya Sifa’ (long dormancy) were planted at National Potato Research Centre, Tigoni and sprayed with a factorial combinations of 0, 50, 100, 300 ppm GA and 0, 50, 75, 100 ppm BA separately and combined at the rate of 1000 lts/ha spray volume towards the end of maturation. The resulting tubers were put in diffuse light storage (DLS) and data on number, length and vigour of sprouts recorded. Sprouted seed tubers were subsequently planted and evaluated for both growth characteristics and yields. The data collected was subjected to analysis of variance and significantly different means were separated using Fisher’ s protected least significant difference at p≤0.05. Higher rates of foliar application of GA+BA (300 ppm + 100 ppm) compared with the control (0 + 0) resulted in significant increase insprout length (cm), number ofsprout/tuber, sprout vigour (score), and % sprouting from 3.24 to 7.02 and 3.84 to 9.03, 2.04 to 4.45 and 2.07 to 4.8, 1.7 to 3.06 and 1.63 to 3.23, 61.21to 86.67and 63.3 to 83.7 in Asante, 2.94 to 8.03 and 2.8 to 7.99, 1.84 to 5.24 and 1.87 to 4.76, 1.3 to 3.0 and 1.27 to 2.63, 50.61 to 92.7 and 52.7 to 85.7in Dutch Robyjn and 0.79 to 6.43 and 1.32 to 6.99, 0.61 to 3.49 and 0.79 to 3.33, 0.61 to 3.03 and 0.73 to 2.83, 22.12 to 85.76 and 28.3 to83.7 in Kenya Sifa after storage in 2008 and 2009 respectively. A combination of BA and GA resulted in significantly more growth than using only GA or BA alone at the same level. Similarly the subsequent tuber numbers per plant and yield (tons/ha) in resultant plants increased from 7.13 to 12.53 and 24.66 to 32.27, 6.93 to 10.47 and 16.73 to 23.37, and 5.63 to 9.6 and 17.53 to 30.13 in Asante, Dutch Robyjnand Kenya Sifa respectively. Combined application of GA + BA at varied rates can be used to improve sprouting characteristics of seed potato and yield of resultant plants.