ARI Biennial Review for 2018-2019

VEGETABLE CROPS The Vegetable Crops Section undertakes research on intensive vegetable production systems, on the postharvest physiology and technology of horticultural commodities, and on the ex situ conservation and utilisation of local plant genetic resources. Current work in Vegetable Crop Science focuses on watermelon and melon rootstock-scion relations with respect to productivity, disease-resistance, stress response, quality and postharvest performance. The Vegetable Crops Section manages national participation in EU Cost Action 1204 (Vegetable Grafting to Improve Yield and Fruit Quality under Biotic and Abiotic Stress Conditions) and participates actively in the Action’s working group on rootstock-mediated effects on vegetable fruit quality. Work on leafy salad crops examines the effect of planting pattern, nitrogen administration strategies, shading, seasonal adaptation and time of harvest on yield, quality, shelf-life and consumer safety. Performance of five male hybrid asparagus cultivars is under trial along with select populations of two wild asparagus species ( A. stipularis and A. acutifolius ) tested for adaptability to intensive cultivation. The Postharvest Technology Laboratory (PTL) is the main analytical facility of the Vegetable Crops Section, dedicated to the study of pre- and postharvest ripening physiology of climacteric and non-climacteric fresh horticultural commodities in relation to the configuration of quality and postharvest performance. The PTL maps the farm-to-fork etiology of fresh produce quality, by studying the impact of pre- and postharvest applications on quality and shelf-life. Analytical emphasis is placed on assessing the implications of harvest maturity for product physiology, on deducing objective indices of physiological and commercial maturity, and on describing physicochemical attributes of quality. The effects of minimal processing on product quality and shelf-life, and the effectiveness of non-chemical postharvest treatments for controlling pathological and physiological loss of quality are also within the scope of PTL current activity. The PTL coordinates the current ARI project on the evaluation of an ex situ collection of indigenous pomegranate clones. The National Genebank constitutes another integral component of the Vegetable Crops Section concentrated on the collection, ex situ conservation, regeneration, characterisation, evaluation and utilisation of native plants of the flora of Cyprus and local landarces. Finally, the ARI Herbarium, which is an extension of the Genebank, is dedicated to the collection and documentation of botanical specimens of the Cyprus flora. VEGETABLE SCIENCE The occurrence of nitrates and nitrites in Mediterranean fresh salad vegetables and its modulation by preharvest practices and postharvest conditions Winter and summer nitrate/nitrite concentrations in 11 salad vegetables were surveyed using a validated HPLC- DAD method. Nitrate was highest in rocket, both in winter (x=3974 mg kg−1 fw) and summer (x=3819 mg kg−1 fw). High nitrate accumulators included spinach, purslane, chards, dill, coriander and parsley. Wide intra-species variability and levels in excess of permitted maxima highlighted the importance of monitoring vegetable production methods to protect consumer health. Occurrence of detectible nitrite (14–352 mg kg−1 fw) was most frequent in winter head cabbage. Three additional experiments examined the seasonal effects of nitrogen (N) fertilisation rate, application method, formulation and postharvest storage on nitrate and nitrite levels in lettuce, rocket and spinach. Violation of current nitrate limits is likely when total N exceeds 200 kg ha−1, particularly in rocket and spinach. Postharvest nitrate reduction requires exogenous microbial nitrate reductase activity, which is unlikely to be achieved without visible loss of quality. (G.A. Soteriou, M.C. Kyriacou) 25 VEGETABLE CROPS − −