ARI REVIEW FOR 2016-2017

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. The main analytical facility of the Vegetable Crops Section is the Postharvest Technology Laboratory (PTL), 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 in close cooperation with the Vegetable Science Laboratory. 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 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 landraces. 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. Current work focuses on watermelon and melon rootstock-scion relations with respect to productivity, disease- resistance, stress response, quality and postharvest performance. The Vegetable Crops Section has managed national participation in EU Cost Action 1204 (Vegetable Grafting to Improve Yield and Fruit Quality under Biotic and Abiotic Stress Conditions) and has participated actively in the Action’s working group on rootstock-mediated effects on vegetable fruit quality. The Section’s work on leafy salad crops examined the occurrence of nitrates and nitrites in a wide range of Mediterranean vegetables and how these are modulated by preharvest practices and postharvest conditions. Moreover, extensive work has been initiated on the cultivation and postharvest behaviour of microgreens, which constitute an emerging functional specialty crop globally. Evaluation of wild vegetable relatives comprised trials of male green asparagus cultivars along with select populations of two wild asparagus species ( A. stipularis and A. acutifolius ) tested for adaptability to intensive cultivation. Finally, the PTL coordinates the ARI project on the evaluation of an ex situ collection of indigenous pomegranate clones. Biochemical and histological contributions to textural changes in watermelon fruit modulated by grafting Increased watermelon fruit flesh firmness is systematically incurred with grafting on Cucurbita hybrid rootstocks (heterografting). Possible differences in mesocarp cell wall constitution and histology between heterografted, homeografted (self-grafted) and non-grafted watermelon were examined, as well as their contributions to fruit texture. Firmness correlated positively ( r =0.78, p<0.001) with cell density (cells mm -2 ) which was higher in heterografts (5.83) than homeografts (4.64) and non-grafted controls (4.69) (Fig 3.1). Mean cell size was smallest in heterografts and correlated negatively ( r = -0.75, p<0.001) with firmness. Cell wall material, particularly the water-insoluble pectin fractions associated with firmness, were highest in heterografts. No associations with firmness were found for cell wall neutral sugars and membrane permeability. Higher parenchymatic cell density with higher content of alcohol insoluble residue and more abundant water-insoluble pectin fractions underscore enhanced firmness in heterografts. Possible implication of osmolytes in rootstock-mediated cell pressure regulation warrants further investigation. ( G.A. Soteriou, M.C. Kyriacou ) 27 Vegetable Crops