Growth and transpiration of tomato seedlings grown in hazelnut husk compost under water-deficit stress
This study was carried out to determine effects of composted hazelnut husk (CHH) on tomato seedlings grown under water stress conditions. Seven media were prepared using CHH mixed, in different ratios, with native peat and perlite. The following mixtures were used: 100%CHH, 100%peat, 75%CHH+25%peat, 50%CHH+50%peat, 25%CHH+75%peat, 25%CHH+50%peat+25%perlite and 50%CHH+25%peat+25%perlite. The experiment was arranged in a randomized plot design with seven media, three water levels (100%, 50% and 25% of easily available water content) and three replicates under greenhouse conditions. After a growing period (until beginning of flowering) of two months, transpiration rate, total dry matter, root/shoot ratio and plant height were measured. Among these media, 50%CHH+50%peat (M2) and 25%CHH+50%peat+25% perlite (M4) were found more ideal media than the others as physical and chemical properties. Water-deficit stress negatively affected seedling growth and transpiration rate. When water deficiency level increased, transpiration rate is decreased. Therefore, plant growth slowed down and total dry matter content of seedlings and plant height decreased. It was found that 50%CHH+50%peat (M2) and 25%CHH+50%peat+25% perlite (M4) media increased transpiration rate, total dry matter and seedling height. Root /shoot ratio increased under water stress in contrary to the other parameters. Root/shoot ratio raised in 100%peat and 50%CHH+50%peat media (M2). For tomato seedlings growth, 25% and 50% CHH can be used in mixtures with peat as a growing media component under water stress conditions. Besides, further research is recommended on the effects different combinations of CHH media for growth of tomato plant exposed to water stress during different growing period (such as flowering and fruit setting).