Assessment of Plant Growth Regulators and Chemicals for Potato (Solanum tuberosum L.) Dormancy Breaking and Subsequent Yield in Central Highlands of Ethiopia

The production of potato in two or more cycles within a year is increasing in the country and it is a common practice in most potato producing regions of Ethiopia. However, the characteristic long tuber dormancy of improved potato varieties in Ethiopia constrains double or triple cropping using irrigation during the long dry season of the year. Thus, it is important to break the long dormancy of tubers for early sprouting and timely planting. Therefore, several types of researches were conducted so far to assess the effect of plant growth regulators and other chemicals to assess its effect on tubers dormancy break, sprouting, sprouts growth, and subsequent effect on tuber yield, yield related and tuber quality of potato varieties. For dormancy break, sprouting and subsequent yield various methods of applications (haulm & dipping) and concentration rates were applied. Moreover, the effect of dormancy-breaking treatment and storage methods were conducted. Results of the studies indicated that, tuber dormancy period and sprout vigour were significantly influenced by the interaction of GA3 and variety, while other sprouting as well as sprout growth traits were significantly influenced by the main effects of GA3 and varieties. The interaction effect of varieties and GA3 significantly influenced days to maturity. Planting of tubers treated with the highest concentration of GA3 produced a significantly highest marketable tuber yield. The optimum tuber size (medium size) for planting purpose was attained from planting of tubers treated with 40 ppm GA3. Significant increase in tuber number and weight due to GA3 application contributed to the increase of total tuber yield. Application of GA3 and storage methods as well as the interaction among the varieties and treatments significantly affected tuber dormancy period, sprouting characteristics and subsequent tuber yield. The mean values for tuber quality (DM & SG) related traits increased in response to treating the tubers with higher concentrations rate of GA3 for both methods of application. Potato varieties treated with GA3 showed significantly higher tuber dry matter yields, specific gravity and total starch content than the other variety. The highest net benefit with an acceptable marginal rate of return was attained in response to treating tubers with higher rates of GA3. Therefore, it could be concluded that haulm application and dipping tuber in GA3 at higher concentration increased tuber yield with a possibility of cultivating potato for two to three production cycles in a year that enhance productivity per unit area, food and nutrition security as well as farmers’ income.