GROWTH AND PHYSIOLOGICAL RESPONSE OF ENSET (Ensete ventricosum) VARIETY ENTADA TO SOLAR UV-B RADIATION AND DIFFERENT PLANTING DENSITIES

Abstract

Ensete ventricosum (Welw.) Cheesman, commonly known as enset, is a monocarpic perennial herb originated in Ethiopia. Propagation is commonly practiced through traditional sucker inducing techniques. However, Entada, which is one of the enset landraces mostly cultivated in southern part of Ethiopia around Ari zone, which unlike other enset landraces, produces natural suckers like banana. Information is lacking about the response of Entada to environmental cues for the regulation of natural suckering of the landrace. Therefore, the present study was conducted during the 2016/2017 off season with the aim of evaluating the effect of UV and planting density on morphogenesis and physiology of Entada plants grown at Hawassa at an altitude of 1700masl. The experiment was carried out in a randomized complete block design with three replications at Hawassa University field research station. The experiment had three level of planting density (0.5m x 0.5m (40,000 plants/ha), 0.75m x 0.75m (17,777plants/ha) and 1m x 1m (10,000 plants/ha) and two level of UV radiation (with solar UV-B radiation and without solar UV-radiation). Data were collected on light quality, morphological and physiological parameters. The analysis of variance showed that planting density and UV-B radiation significantly influenced light quality distribution, morphology and physiology of plants. It was observed that, total number of sucker and suckering ratio were significantly (p<0.05) affected by UV, planting density and their interaction. The highest planting density induced reduction in R: FR ratio significantly increased plant height by 18% but the number of suckers was reduced by 45% as compared to lowest. However, UV-B had stronger effect on plant height than planting density. Maximum number of suckers were recorded (47.3) from treatment combination of lower planting density (with higher R:FR ratio) and without UV-B radiation. Leaf number significantly responded to UV but not to the changing in planting density. With respect to specific leaf area, dry matter and total biomass no significant effects was observed among planting density, but significantly reduced by solar UV radiation. Photosystem II efficiency (Fv/Fm) significantly responded to UV than planting density. Removing UV-B radiation using plastic film significantly increased photosystem II efficiency (Fv/Fm) of leaves by 2.5%. Although stomata aperture significantly responded to UV than planting density, the stomata number showed a reduction pattern with increasing planting density. Generally, change in the composition of light quality using planting density and screening material approach has a significant effect on the modification of sucker development and morpho-physiological growth condition of Entada.