Etissa E, Dechassa N and Alemayehu Y
Two field experiments were conducted to study fruit yield and physiological responses of field grown tomato. The first experiment was conducted with container grown during rainy season by combining three factors namely, two levels of N (0 and 25 kg N ha-1), and two levels of P (0 and 23 kg P ha-1) fertilizers and with six locally available media mix ratios (MR). The experiment was laid down on CRBD in a factorial arrangement and replicated three times. The second experiment was conducted under drip irrigation during hot dry season with three levels of daily irrigation applications: full irrigation, 80% and 60% of daily ETc irrigations. Data on marketable, unmarketable and total fruit yield were recorded and some physiological responses: quantum yield, leaf chlorophyll content and fluorescence, and stomatal conductance were assessed from sample plant leaves using various sensors. The results of container grown experiment indicated that use of combinations of starter N and MR showed a significant effect (P<0.05) on the marketable fruit yield, similarly use of media mixtures had highly significant (P<0.01) influence on the unmarketable fruit yield and finally use of media mix ratio showed a highly significant effect (P<0.01) on the total fruit yield of container grown tomato. MR3 yielded the highest total fruit yield while MR6 gave the lowest total fruit yield. Application of starter N, P or media mix did not bring any combined effect (P<0.01) on the leaf chlorophyll content. However, application of starter N caused a highly significant (P<0.01) effect on leaf quantum yield. The results of drip irrigated experiment indicated that use of various irrigation depth brought a significant (P<0.01) effect on the marketable yield of tomato. The highest fruit yield was recorded in response to full irrigation, while the lowest marketable fruit yield was recorded from 60% of full irrigation. Irrigation depth significantly (P<0.01) affected the tomato leaf chlorophyll content. The highest irrigation level increased leaf chlorophyll content and lowest irrigation depth reduced leaf chlorophyll content. Irrigation depth brought significant (P<0.01) effect on the stomatal conductance as irrigation depth decreased, leaf stomatal conductance was highly reduced. Measuring quantum yield, leaf chlorophyll content, and fluorescence and stomatal conductance of tomato plant there is indicated direct relation with yield performance that would give instant improvement of management practices of the crop. Thus further research is required to fine tune and use of this physiological response with the crop yield.
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