Water and nutrient uptake of sweet pepper and tomato as (un) affected by watering regime and salinity

Scarcity or poor quality of irrigation water is increasingly becoming the "way of life" for growers in many mild climate regions. Water can be saved by two means: watering as little as possible (limit losses through drainage) or abundant watering with recollection and re-use of drainage (closed systems). Either way, an additional positive side effect is the reduction in pollution caused by percolation of fertilisers. However, both growing systems have risks: limited watering results in higher concentration of salts in the root zone, and all unused ions accumulate in closed systems. Since it is well known that increased salinity reduces yield (though it may increase product quality), growers are not keen to embrace such water-saving techniques. The objectives of this work were to investigate whether good-quality water can be saved by reducing drainage in open systems; and whether brackish water can be used in closed ones. We present the results of two concurrent experiments: one with drain-less watering in sweet pepper and one with (semi)closed water cycle in tomato. The sweet pepper experiment was designed to allow for limited watering (with good-quality water) without increase in salt concentration, and we show that the ability of plants to absorb water and to take up nutrients is independent of the watering regime (provided there is enough water in the root zone). The tomato experiment, on the contrary, allowed for salinity build-up by using brackish water in a closed system and we show that water and nutrients uptake is largely unaffected by salt accumulation (within boundaries), though there is a reduction in fresh yield, as expected.