Desalinated water has become a legitimate alternative water resource for the irrigation of intensive crops in semiarid regions. The concentrations of calcium (Ca) and magnesium (Mg) in water (CCa and CMg, respectively) supplied from desalinated plants are much lower than the values typically found in irrigation water resources in semiarid regions. blossom-end rot (BER), a physiological disorder at the blossom-end part of the fruit resulting in tissue disintegration and dehydration, is considered a Ca-related disorder and therefore the optimization of CCa has to consider not only total fruit production but also the occurrence of BER. There is a lack of information regarding the optimal CCa and CMg and Ca/Mg ratio in low-salinity water under Mediterranean conditions for high-quality yield of tomato fruits.
The main objective of the research was to optimize CCa and CMg for the production of high tomato fruit yield with minimal occurrence of BER. A secondary objective was to determine critical levels of Ca, Mg and Ca/Mg ratio in leaves in relation to yield and the occurrence of BER.
Tomato plants were grown in an inert media and fed with a wide range of CCa and CMg. Fruit yield was shown to decrease significantly when CCa was at or below 0.40 mmol l–1. In moderate CMg (1.4 mmol l–1) treatment, BER was negatively correlated to Ca level up to and including 1.4 mmol l–1 and was not manifested above that level under the prevailing conditions. Elevating CMg above 0.25 mmol l–1 enhanced BER occurrence. Concentrations of Ca and Mg in tomato organs increased with the respective mineral concentration in irrigation solution, whereas each element was reduced in organs as a function of the increased solution concentration of the other. The Ca concentration in diagnostic leaves (the diagnostic leaf is the fully developed youngest leaf) for optimal fruit yield with minimum BER was found to be 1.6%. The optimum CCa for high fruit yield with minimal BER occurrence was found to be in the range of 1.5–2.5 mmol l–1 combined with CMg at 0.25 mmol l–1.
While the environmental impacts of religious and secular holidays are increasingly characterized, interventions to reduce their effects are modest and poorly understood. Israel’s L’ag B’omer holiday has emerged as a major air pollution source due to the common practice of lighting bonfires. We implemented and evaluated an intervention amongst Israeli school children in which they were challenged to design and adopt alternative “environmentally friendly” celebrations that maintained the holiday spirit. The interventions were observed and a mixed method approach applied to study implementation involving, interviews with teachers, parents and students as well as an ex-post questionnaire answered by participants. Children supporting environmental celebrations displayed higher levels of environmental behavior, and environmental hope than those preferring bonfires. Those who voted for an environmental alternative, against the majority, also displayed higher levels of self-control skills. The study confirms the potential of well-designed, environmentally friendly holiday celebrations to replace environmentally deleterious ones.