Optimum ratio of calcium and boron in the nutrient solution or in castor bean shoot for fruit yield and seed oil content - Franco, Henrique Coutinho Junqueira; Lavres Junior, José; Oliveira Junior, Adilson de; Matias, Gean Carlos Silva; Cabral, Cleusa Pereira; Malavolta, Eurípedes (Journal of Plant Nutrition, 2012)