STUDY ON PRODUCTION PRACTICE AND EFFECT OF GENOTYPE, IRRIGATION AND ZINC FERTILIZATION ON PRODUCTIVITY AND QUALITY OF POTATO IN SEMI-ARID ENVIRONMENT OF TIGRAY, ETHIOPIA

Abstract

Potato is the fourth most important world food crop after wheat, rice, and maize because of its great yield and high nutritional value. It is also an important crop among the root and tuber crops grown in Tigray. However, productivity is very low due to moisture stress, climatic variability, traditional agronomic practices that growers undertake, the use of low-yielding varieties and other production constraints. A series of studies were conducted to assess the current potato production practices of smallholder farmers, identify key opportunities and constraints, analyze climate variability and its implications for potato production, and evaluate the relationship between historical climate data and farmers' perceptions. The studies also aim to optimize potato yield by evaluating suitable genotype both under supplement and under nonsupplement irrigation conditions, assess the effects of genotypes and irrigation levels on growth, yield, quality, water use efficiency, and drought tolerance, and examine the effect of Zn fertilizer rates, genotypes, and irrigation levels on yield, quality, and nutrient use efficiency in potatoes. The study used surveys, long-term climate analysis, and field experiments on various potato genotypes and irrigation levels. Survey was conducted in major potato production areas. Long-term daily rainfall and temperature data analysis as well as an interview were carried. For the field experiment five potato genotypes with two and three irrigation levels were used as treatments under rain-fed and irrigation condition, respectively arranged in split plot using randomized complete block design with three replications. Furthermore, three potato genotypes, three-irrigation levels and five Zn fertilizer rates were used as treatments arranged in a factorial complete randomized design with three replications, conducted under controlled screen house conditions . Mann–Kendall test and Sen's slope estimator statistical trend analysis techniques were used to analyze the climate variability , SPSS , and SAS software were used to analyze the qualitative and quantitative data/. The survey result confirmed that potato is the main horticultural crop in the study areas, serving as a source of cash, food, and seed under both irrigation and rain-fed conditions. The average tuber yield under irrigation ranged from 12.6 to 15.0 tons per hectare, while under 2 rainfall conditions, it ranged from 12.4 to 14.6 tons per hectare. Key opportunities for potato production in the study areas include suitable agro-ecological conditions, good soil types, access to irrigation water, and available labor. However, persistent challenges, including diseases and pests, a lack of improved varieties, drought, and limited market access were identified. The study revealed that rainfall patterns in the study areas are showing decreasing trends in annual and seasonal rainfall, coupled with rising temperatures. The seasonal rainfall in the study areas was also highly variable and unevenly distributed. This variability negatively affects the kiremt season, characterized by lateonset and early cessation of rainfall, ultimately shortening the growing period. Farmers have also perceived these changes, noting reduced rainfall and increased temperatures that adversely affected crop production. The study indicates that the interaction between irrigation and potato genotypes significantly affected maturity, yields and water use efficiency under both rain-fed and irrigation conditions. The highest marketable and total tuber yields, along with shorter days to flowering and maturity, were obtained from the genotypes CIP-394611.112 and CIP-390478.90 under both supplemental and full irrigations. Under full irrigation, CIP-394611.112 produced the highest total tuber yield (29.87 t ha⁻¹). Under rainfall with supplemental irrigation, CIP-390478.90 produced the highest yield (28.71 t ha⁻¹).A pot experiment also revealed that the genotype CIP394611.112 with 100% and 75% irrigation levels produced the highest total (0.28 and 0.256 kg pot-1 respectivly) and marketable tuber yields (0.267 and 0.247 kg pot-1 respectivly). The study recommends strengthening extension services for Integrated Pest Management (IPM) and promoting water-harvesting techniques to address the primary constraints of pests and drought. Furthermore, it advocates for building a robust seed system by supporting local seed multipliers and strengthening the formal seed sector. A key long-term strategy is breeding improved varieties with enhanced drought tolerance and resistance to local diseases. Research institutions and NGOs should also focus on developing high-yielding drought-tolerant varieties and producing high-quality seed tubers of improved varieties through the establishment of a potato seed multiplier association. In summary, the studies provide valuable insights and recommendations for mitigating the effects of climate change and improving potato production in the Tigray region and other similar areas of Ethiopia. Key interventions include developing and disseminating drought-tolerant potato genotypes, as well as adopting efficient water management practices like small-scale irrigation and rainwater harvesting to offset rainfall variability