Effect of boron on ear formation and yield components of two maize (Zea maysL.) hybrids

In sand culture, the effect of various B concentrations in nutrient solution on ear formation and yield response of maize cultivars Mutin and Carlos Semu 201 was investigated. Under continuous B supply, as the B concentration in the solution was raised, ear‐leaf B increased linearly in Mutin (r = 0.93) but nonlinearly in Carlos Semu 201 (R2 = 0.75) and reached 29.1 and 28.1 mmol kg–1, respectively, without showing any unequivocal toxicity symptoms for B. Interruption in the B supply (from one week prior to tasseling until maturity) curtailed the normal development of the ear, which was more severe in Mutin than in Carlos Semu 201. Critical ear‐leaf B concentrations for stover, total, and ear yield were higher in Mutin (3.8, 14.8, and 25.3 mmol kg–1) than in Carlos Semu 201 (1.9, 6.0, and 8.4 mmol kg–1). The data indicate that the B requirement of the hybrids tested is different and is higher than the most‐cited values. The higher critical B levels observed for stover, total and ear production indicate that B plays an important role in the storage of assimilates in maize.