Mineral Nutrition of Aeroponically Grown Subtropical and Temperate Crops in the Tropics with Manipulation of Root-Zone Temperature at Different Growth Irradiances

Plant growth and productivity are often limited by high root-zone temperatures (RZT) which restricts the growth of subtropical and temperate crops in the tropics. High RZT temperature coupled with low growth irradiances during cloudy days which mainly lead to poor root development and thus causes negative impact on the mineral uptake and assimilation. However, certain subtropical and temperate crops have successfully been grown aeroponically in the tropics by simply cooling their roots while their aerial portions are subjected to hot fluctuating ambient temperatures. This review first discusses the effects of RZT and growth irradiance on root morphology and its biomass, the effect of RZT on uptake and transport of several macro nutrients such as N [nitrogen, mainly nitrate, (NO3 )], P (H2PO4 , phosphate), K (potassium) and Ca (calcium), and micro nutrient Fe (iron) under different growth irradiances. The impact of RZT and growth irradiance on the assimilation of NO3 (the form of N nutrient given to the aeroponically grown plants) and the site of NO3 assimilation are also addressed. _____________________________________________________________________________________________________________