Optimum Polyethylene Glycol Level Suitable for Inducing Water Stress in Potato (Solanum tuberosum L.) Genotypes in Kenya

Judith Oggema; Anthony Kibe; Maurice Oyoo; Miriam Mwangi

Judith Oggema Agricultural Development Corporation (ADC), P. O. Box 47101-00100, Nairobi, Kenya
Anthony Kibe Department of Crops, Horticulture and Soil Science, Faculty of Agriculture, Egerton University, P. O. Box 536- 20115, Njoro, Kenya
Maurice Oyoo Department of Crops, Horticulture and Soil Science, Faculty of Agriculture, Egerton University, P. O. Box 536- 20115, Njoro, Kenya
Miriam Mwangi Department of Crops, Horticulture and Soil Science, Faculty of Agriculture, Egerton University, P. O. Box 536- 20115, Njoro, Kenya

Keywords: potato, in-vitro, PEG, genotype, moisture stress

Abstract

Water stress is a critical abiotic constraint that reduces crop productivity by preventing the expression of the genetic potential. Breeding programs prioritise developing climate smart resilient potato cultivars, that are pathogen-resistant, high-yielding and commercially viable. Modern biotechnological approaches, including in vitro drought stress screening using polyethylene glycol (PEG) 6000, have enhanced efficiency in identifying tolerant genotypes. PEG uniformly reduces water potential, mimicking soil moisture deficits. This study determined the optimal PEG level for inducing water stress in selected potato genotypes including; CIP390478.9, CIP397077.16, CIP392797.22, CIP398190.735, and local varieties Unica as tolerant and Shangi as sensitive checks. A randomized complete block design (RCBD) with five PEG levels (0.0–0.04 gL⁻¹) was replicated thrice, conducted at ADC Molo Tissue Culture Laboratory. Significant differences (P<0.05) in performance were observed among genotypes and PEG levels. Morphological parameters were highest at 0.02 gL⁻¹ PEG, with CIP392797.22 exhibiting superior tolerance, followed by CIP398190.735. Shoot and root development declined at higher PEG levels (0.03 - 0.04 gL⁻¹). These finding underscored the use of PEG in screening drought-tolerant genotypes for other areas in Kenya.

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