Growth and Morphology of Pea (Pisum sativum cv. Oregon sugar pod II) Plants grown Under Different Shading Screens at Hawassa, South Ethiopia

Abstract

A field experiment was conducted in the dry seasons of (2016 and 2017) at Hawassa to assess the effects of three greenhouse-covering materials (Svensson with strip ventilation, white and yellow plastic films) on growth and development of pea plants. Plants grown under the Svensson screen were 5.1– 6.4 cm taller, had 2–3 more internodes and the internodes were 0.44– 0.59 cm longer as compared to those grown under the yellow and the white plastic screens. However, no significant differences in dry matter or pod number were found between the screens. The difference in morphology was mainly due to the reduced transmittance of photosynthetic active radiation (PAR) and ultraviolet (UV) radiation of the Svensson as compared to the white and yellow plastic screens. Significantly smaller stomata aperture and lower leaf conductance were found on plants grown under yellow plastic film as compared to the imported screens. Thus, plants grown under yellow plastic film had 17% and 37% lower transpirational water loss as compared to the Svensson and the white plastic screens, respectively. Maximal PSII efficiency (Fv/Fm) was also lower in the locally produced yellow film as compared to the two imported screens, but Fv/Fm was not correlated with pod number. In conclusion, growth and development of pea are robust to changes in light climate. The cheap locally produced yellow plastic screen with relatively high PAR and UV transmittance is a suitable screen in the production of pea and as an efficient tool to control transpirational water loss in warmer regions like Ethiopia.