Comparison of date-palm wastes and perlite as growth substrates on some tomato growing indexes

Today, various organic matters are used as growth media. Most of them are combined with various materials, such as a mixture of peat moss and pine bark, or a mixture of peat moss and pine bark with mineral materials like perlite or vermiculite. All over the world, stone wool and other materials like perlite, pumice, polyortan phome, zeolite, coco peat and sawdust are used as growth media in soilless culture. The objective of this study was to assess the effects of incubation time on the physicochemical properties of date palm wastes and their effects on growing indexes of tomato in comparison with perlite when used as culture substrates. The date palm wastes were first manually chopped into small pieces, after which they were kept in plastic bags. They were adjusted to 55% moisture content and thoroughly mixed once every week. Treatments were done for 4 incubation times (0, 1, 3 and 9 months). The physicochemical properties of materials were analyzed during 3 months. After 3 months of incubation, for comparison of this composting materials (date-palm) with other substrates, perlite and the composting materials were used as growth media. The research was conducted in a completely randomized design with 6 replications of tomato for 6 months. Treatments included perlite, date-palm1 (without incubation time) and date-palm2 (with 3 months incubation time). During plant growth irrigation rate, temperature, humidity and pest control for all treatments were similar. During plant growth, Papadopolus formula with fertigation method was used for the nutrient solution. The plants were kept for 6 months, then after this period, the physicochemical properties of these materials were analyzed again. So, the growing indexes of tomato, which included fruit yield, plant height, fruit  number, stem diameter, TSS and biomass, were measured. The results of incubation time period showed that changes of porosity, bulk density, pH, C/N ratio and CEC had significant differences (p<0.05). The C/N ratio reduced, while the bulk density and CEC increased by the increase in incubation time period. Comparison of tomato growing indexes in the different substrates showed that fruit yield, plant height and fruit number of tomato had no significant differences at 5% level, but stem diameter and biomass in date-palm1 was higher than other media and thus, had significant differences at 5% level.Key words: Date palm wastes, incubation time, aerating, perlite, fertigation, tomato

Closed hydroponic systems : operational parameters, root exudates occurrence and related water treatment

Greenhouse production of vegetables in closed hydroponic cropping systems is a resource-efficient technique for the production of high-quality produce with a high yield per unit area. Recently, there have been considerable progresses in the development of hydroponic culture. While this type of cropping system allows savings in terms of water and nutrient use, the recirculation of water increases the risk of root exudates dispersal. Plant roots often exude numerous organic acids, which are known to inhibit growth. So far several methods have been found to be effective in removing or degrading the phytotoxic substances released from plant roots during autotoxicity such as adsorption by activated carbon, electrodegradation of root exudates and TiO2 photocatalysis. In this review an overview will be presented of hydroponic systems and their related root exudates occurrence and removal