Using Date Palm Waste as an Alternative for Rockwool: Sweet Pepper Performance under Both Soilless Culture Substrates.

The degradation of soil quality due to environmental conditions and improper management practices has caused a shrinkage in land areas suitable for crop cultivation. This necessitates a transition towards soilless culture systems, which offer desirable conditions for crop growth and development and increase resource use efficiency. One of the growth-limiting factors in soilless culture systems is the type of growing substrate. The use of more sustainable resources and environmentally friendly growing substrates is a challenge that affects the soilless culture industry. This work evaluates the efficacy of date palm waste (DPW) and rockwool as growing substrates for sweet pepper (Capsicum annuum L.) under greenhouse conditions. The plant height, stem diameter, average total leaf area, φPSII, and Fm' of leaf fluorescence show significant increases when plants are grown in rockwool. No differences are found in terms of the total yield or the number of marketable fruits and fruit quality between the two substrates. However, the DPW substrate shows a significant decrease in the number of unmarketable fruits and number of Blossom End Rot (BER) fruits. Plants grown in both growing substrates consume equal water amounts for the optimal fruit production, while the water use efficiency of rockwool is better than that of DPW. Our results highlight DPW's role in soilless production and as a key solution for resource-saving production systems.

Perchlorate, nitrate, and iodine uptake and distribution in lettuce (Lactuca sativa L.) and potential impact on background levels in humans.

Much focus has been placed on the impact of exposure to perchlorate (ClO4(-)) from drinking water. Recently, it has become more apparent that a significant percentage of the total ClO4(-) exposure may be due to ingestion of food. Most studies have only evaluated the uptake and distribution of ClO4(-) by plants without considering the potential for uptake of iodine (I) by the plant and the subsequent impacts on ClO4(-) uptake and distribution on human health. The objectives of this research effort were to evaluate the relative uptake of ClO4(-) and I supplied as either KI or KIO3, the two major environmental forms of I in a standard hydroponic nutrient solution using butter head lettuce. No interaction of ClO4(-) uptake and distribution was found in the presence of I(-) or IO3(-) relative to previous studies evaluating ClO4(-) alone. Bioconcentration factors for ClO4(-) and total I in butter head lettuce when coexposed to both anions were similar for outer (292 ± 17 and 294 ± 12 L kg(-1) of dry weight, respectively) and inner (76 ± 18 and 60 ± 8 L kg(-1) of dry weight, respectively) leaves but not for roots (23 ± 3.7 and 359 ± 1.7 L kg(-1) of dry weight, respectively) when the iodine was supplied as I(-). The uptake of iodine was lower (BCF = 47 ± 3.8, 19 ± 0.6, and 189 ± 16, L kg(-1) of dry weight for the outer and inner leaves and roots, respectively) for all tissues when iodine was supplied as IO3(-), with the greatest accumulation by the roots. These results suggest that if lettuce is grown using fertilizers containing both ClO4(-) and I(-), then the final ratio of IT/ClO4 in the leaves will be essentially equal to the ratio in the fertilizer but lower if the I is supplied as IO3(-). Therefore, the impact of the consumption of lettuce containing ClO4(-) may be mitigated if the lettuce is grown using fertilizer with an appropriate amount of I to maintain the existing ratio of serum I to total goitrogen load (TGL). Nevertheless, the TGL in lettuce appeared to be almost completely dominated by NO3(-) with only a minor contribution of ClO4(-), even for the highest exposure to ClO4(-).

Biofortification of lettuce (Lactuca sativa L.) with iodine: the effect of iodine form and concentration in the nutrient solution on growth, development and iodine uptake of lettuce grown in water culture.

BACKGROUND: Iodine is an essential trace element for humans. Two billion individuals have insufficient iodine intake. Biofortification of vegetables with iodine offers an excellent opportunity to increase iodine intake by humans. The main aim was to study the effect of iodine form and concentration in the nutrient solution on growth, development and iodine uptake of lettuce, grown in water culture. RESULTS: In both a winter and summer trial, dose rates of 0, 13, 39, 65, and 90 or 129 microg iodine L(-1), applied as iodate (IO(3)(-)) or iodide (I(-)), did not affect plant biomass, produce quality or water uptake. Increases in iodine concentration significantly enhanced iodine content in the plant. Iodine contents in plant tissue were up to five times higher with I(-) than with IO(3)(-). Iodine was mainly distributed to the outer leaves. The highest iodide dose rates in both trials resulted in 653 and 764 microg iodine kg(-1) total leaf fresh weight. CONCLUSION: Biofortification of lettuce with iodine is easily applicable in a hydroponic growing system, both with I(-) and IO(3)(-). I(-) was more effective than IO(3)(-). Fifty grams of iodine-biofortified lettuce would provide, respectively, 22% and 25% of the recommended daily allowance of iodine for adolescents and adults.

Kasza: design of a closed water system for the greenhouse horticulture.

The need for a closed and sustainable water system in greenhouse areas is stimulated by the implementation in the Netherlands of the European Framework Directive. The Dutch national project Kasza: Design of a Closed Water System for the Greenhouse Horticulture will provide information how the water system in a greenhouse horticulture area can be closed. In this paper the conceptual design of two systems to close the water cycle in a greenhouse area is described. The first system with reverse osmosis system can be used in areas where desalination is required in order to be able to use the recycle water for irrigation of all crops. The second system with advanced oxidation using UV and peroxide can be applied in areas with more salt tolerant crops and good (low sodium) water sources for irrigation. Both systems are financially feasible in new greenhouse areas with substantial available recycle water.