Influence of controlled water deficit at different levels of fertilization on the yield of greenhouse tomatoes

Antoniya Stoyanova, Georgi Kostadinov and Milena Moteva

Abstract: The main objective of this study is to analyze the mutual influence of different irrigation regimes and fertilization rates on the greenhouse tomato yield and on the irrigation water use efficiency. Different irrigation schedulings have been studied in order to establich the impact of water deficit on the tomato productivity and quality. The study is achieved through an experiment with tomatoes in polyethylene unheated greenhouse during 2016-2018. An important role in the technology plays fertilization with different rates. The focus in this experiment is on the effect of a controlled water deficit achieved by reducing the irrigation depth at different levels of plant nutrition on the productivity of greenhouse tomatoes and water use efficiency. In studies interval of irrigation depth and fertilizer rate was found significantly stronger influence of the fertilizer rate on yield. The impact of irrigation on the yield is lower at the lower fertilizer levels. It has greater effect at the higher levels of the irrigation rate. Close to the maximum yield - over 100 Mg/ha can be obtained also by applying the maximum fertilization rate and 80% of the full irrigation depth. The greatest relative additional yield (RAdYn) can be obtained by maximum irrigation depth and maximum fertilizer rate and irrigation has greater effect at maximum and close to it fertilization rates. Maximum water use efficiency can be obtained by a minimum amount of irrigation water and maximum fertilization. Moreover, irrigation has small impact at lower fertilization rates (up to 50%), i.e. WUE is small. The analysis of the the utility function, which summarizes the conditions for obtaining maximum yield and maximum water use efficiency indicates that it maximum value can be obtained at maximum fertilizer rate and 60-70% of the full irrigation depth.

Keywords: efficiency; fertilization; irrigation regime; tomato; yield

Date published: 2020-12-14