Comparison of the subirrigation and drip-irrigation systems for greenhouse zucchini squash production using saline and non-saline nutrient solutions

Soilless cultivation is a method that permits the achievement of high yields, good control of plant growth and development, and is currently in practice all over the world. Several irrigation systems have been developed for containerized-crops (drip-irrigation and subirrigation). Irrigation system can significantly impact the effect of irrigation water salinity on crop performance. Comparing the subirrigation and drip-irrigation systems using saline and non-saline nutrient solutions can be useful for developing optimal management strategies in semiarid regions which are characterized by the shortage of good quality water. A greenhouse experiment was carried out during the spring-summer season to determine the influence two irrigation systems (drip and subirrigation) and two nutrient solution concentrations (2.0 and 4.1 dS m−1) on substrate electrical conductivity (ECe), growth, yield, fruit quality (dry matter, carbohydrates, protein, Vitamin C), yield water use efficiency (WUEy) and tissue mineral composition of zucchini squash (Cucurbita pepo L.). At the mid and at the end of the trial, plants grown with the subirrigation system resulted in a higher ECe in the upper and lower parts of the substrate in comparison to the drip-irrigation system, especially at an EC of 4.1 dS m−1. At an EC of 2.0 dS m−1, zucchini yield (total and marketable) was 13% lower with the subirrigation than with the drip-irrigation systems but offered several benefits: higher fruit quality (dry matter, glucose, fructose, starch and total carbohydrates content) and WUEy. The yield reduction with subirrigation was more pronounced at an EC 4.1 dS m−1, where the zucchini production with subirrigation was lower by 36% than with drip-irrigation. Increasing salinity from 2.0 to 4.1 dS m−1 improved fruit quality (high content of dry matter, reduced sugars, starch, total carbohydrates, and Vitamin C) in both irrigation systems. The results indicate that the choice of the irrigation system appears to be of foremost importance especially when using low quality irrigation water. Unlike subirrigation, using drip-irrigation with saline solution (4.1 dS m−1) would be an attractive strategy in limiting yield reduction, taking advantage of the quality effect of saline water and improving the WUEy.