This research was carried out to determine the changes in melatonin and tryptophan contents and the possible effects of melatonin on the ageing process of lettuce seeds stored for two years. For this purpose, seeds were treated with melatonin (0 or 250 µM) for one day after which they were stored for up to two years at two temperature (4°C or 25°C) regimes. The results showed that seed melatonin content varied significantly during storage reaching its peaks in October-December and lowest levels in August while tryptophan levels displayed an opposite trend with a strong peak in August and low levels in October. Similar seasonal changes were observed in seeds stored under both temperature conditions suggesting that endogenous melatonin could play a crucial role in seasonal rhythms independent of environmental conditions. Lettuce seed quality deteriorated fast when stored at 25°C but pre-treatment with melatonin reduced seed deterioration significantly by increasing the activities of antioxidant enzymes and restoring membrane properties indicating that melatonin could be used to slow the ageing process in seeds.

Uncertainty about climate change exposes agriculture to high risks. Magnetic field (MF) applications are one of the methods that can be used to reduce the effects of environmental stress conditions. Melatonin (MEL) acts as a broad-spectrum antioxidant in eliminating the effects of damage caused in plants exposed to stress. This study aims to examine the effect of MF and ultrasound (US) applications on endogenous MEL levels in peppers and investigate the usability of treated seeds against drought stress. Pre-sowing pepper seeds, 0, 0.3, 0.9, 1.1 T MF and 0, 15, 30 min 40 Hz US were applied. The results show that the highest increase in MEL content was detected at 0.3 T MF with 82% and with 30 min of US application at 98%. MF and US treatments decreased the malondialdehyde (MDA) (19% and 35%, respectively) and hydrogen peroxide (H₂O₂) (52% and 58%, respectively) contents in seedlings. An increase of 24% and 22% (MF-US, respectively) was observed in catalase (CAT) enzyme activity with these applications. As a result, it was observed that MF and US treatments increased the endogenous MEL content and provided tolerance against drought stress. MF and US applications could be suggested as methods to increase drought tolerance in peppers by increasing the endogenous MEL content.

The purpose of this study was to explore the possibilities of improving chilling stress tolerance of eggplant seedlings through exogenous melatonin (MEL) application. Eggplant (Hadrian F1) seedlings were treated with various concentrations (0, 1, 5 or 25 μM) of MEL via soil drench after which they were subjected to chilling stress at 5°C/10°C (night/day) for 3 days. Following stress imposition, the efficacy of MEL applications on enhancing chilling stress tolerance was determined by several physical and physiological measurements and biochemical analyses. The results demonstrated that exogenous application of MEL alleviated the adverse effects of chilling stress in eggplant seedlings. Among the MEL concentrations tested, 5 µM was determined as the most effective concentration since antioxidant enzyme (CAT, POX and APOX) and photosynthetic activities increased while visual and membrane damage decreased in 5 µM MEL-treated seedlings. Also, these results are the first experimental evidence that exogenous application of MEL could improve chilling stress tolerance in eggplant, but further detailed studies are necessary to better understand the mechanism in acquiring chilling tolerance.

ISHS VII International Symposium on Seed, Transplant and Stand Establishment of Horticultural Crops - SEST2016 Investigating the effects of melatonin application on the ageing process of pepper seeds

One of the biggest threats to agro-ecosystems, especially in arid and semiarid areas, is the deterioration of soil quality, which is associated with low soil organic matter levels. Despite the elevated volume of publications related to soil quality and crops, information about specific plants such as the Capia pepper (Capsicum annuum L. cv.) with clear economic relevance in semiarid environments is missing. The aim of present study is to investigate the effects of different doses of manure on Capia pepper focusing on soil–plant interaction, soil quality, and plant yield in an experimental area located in Turkey. Key soil properties were monitored and relationships between plant and soil properties were evaluated using the principal component analysis (PCA). At the end of the first and second growing season, the effects of manure application on some plant and soil characteristics were statistically significant at different levels. According to the PCA result, 15 plant characteristics and 7 soil characteristics were grouped into five factors and defined 85.4% and 90.9% of the total variability in the population in the first and second growing seasons, respectively. Our research concluded that sustainable soil management such as the use of specific dose of manure improves soil quality and plant productivity.