ARI Biennial Review for 2018-2019

NATURAL RESOURCES AND ENVIRONMENT The research work of the Natural Resources and Environment (NRE) section concerned irrigation and fertilisation of crops, soil fertility, the use of treated waste water in agriculture, sustainable use of soil, water and energy, precision agriculture, biodiversity conservation and environmental issues in order to assist efforts for sustainable and viable agriculture under the impact of climatic change. An important part of the research work has been accomplished within the framework of competitive programmes from various funding agencies, such as the European Union, and the Research and Innovation Foundation of Cyprus. PLANT NUTRITION AND SOILLESS CULTURE Soilless culture (SC) is the most intensive production method in today’s greenhouse industry, recognised globally for its ability to promote resource-efficiency and intensive plant production and, at the same time, to apply environmentally friendly technology. However, in Mediterranean countries, SCs have been performing below their potential. Particularly, irrigation and plant nutrition are the most important components, which enable farmers to control product yield and quality in the context of smart agriculture. Finally, in modern greenhouse horticulture, sustainable production mainly relies on hydroponic systems with reuse of drainage water, since a close control in the supply of water and nutrients is impossible in soil-grown crops. Modelling Ca 2+ accumulation in soilless zucchini crops: Physiological and agronomical responses Existing empirical models capable of predicting salt (NaCl) accumulation in closed-loop irrigation systems were further extended to simulate Ca 2+ concentrations in the root environment of zucchini crops. The mean uptake ratios of nutrients (i.e., N, P, K, Ca and Mg) and water denoted as uptake concentrations (UCs) were determined within a wide range of Ca 2+ concentrations in the root zone, and may be used as a rough basis for the establishment of nutrient solution compositions for closed hydroponic Mediterranean zucchini crops. Photosynthesis, plant growth, yield and water uptake were restricted above a nutrient-induced EC value in the recycled solution of 3.2 dS m -1 related to osmotic potential effects (avg. 15% decrease up to 5.5 dS m -1 ). However, water resources containing up to 3 mM Ca 2+ can be safely used in closed hydroponic crops of zucchini (raised Ca 2+ level up to 12 mM) in terms of growth, yield and quality of the produce. (D. Neocleous) 48 NATURAL RESOURCES AND ENVIRONMENT