The effects of substrate physical properties on growth and irrigation water use efficiency of greenhouse tomato transplant

Substrate is one of the most important factors in soilless cultures. Growers of horticultural crops usually select substrates based on physical and chemical characteristics. In order to evaluate the effects of some of the most important physical properties of media, on growth and irrigation water use efficiency of greenhouse tomato transplant, physical properties (water holding capacity, effective air filled pore space and effective pore space) of 50 mixed media were measured. Media which had the same physical properties among the mixed media were selected as experimental treatments to grow greenhouse tomato transplants. Randomized complete block design with 3 replications and 12 observations in each experimental unit was used for the experiment. Results showed that maximum and minimum plant total dry weight, leaf area and leaf number was recorded in sand-cocopeat and perlite-vermiculite media, respectively. Sand- cocopeat and perlite-cocopeat media had the same values of stem diameter, plant height and height of the first node especially during first 2 weeks. Maximum and minimum irrigation water use efficiency (1.17 g/l and 0.34 g/l) occurred in sand-cocopeat and perlite-vermiculite media, respectively. Results indicated that although studied media had the same water holding capacity, but the best growth and irrigation water use efficiency was obtained on sand-cocopeat medium which had a higher amount of easily available water. According to results, it can be concluded that the same water holding capacity of two media doesn’t necessarily guarantee similar results from them and other properties must be taken in account.