Efeitos do fósforo, zinco, cobre e molibdênio na produção de feijão-de-corda cultivado em cambissolo da chapada do Apodi, Ceará.

Abstract

The caupi (known in Brazil as feijão-de-corda) is mainly grown in tropical and semiarid regions. Traditionally this type of beans make up the basic food used by populations in Northeastern Brazil, specially in the State of Ceará. lt is a crop adapted to many different both soil and climate conditions and is planted alI over the State including the Apodi plateau area. The objective of the present investigation was to study the effects of applications of Phosphorus, Zinc, Copper and Molydenum on caupi yield grown in a Cambisol soil under greenhouse conditions. The experimental design was a entirely randonmized blocks (a cross factorial 3x2x2x2), with twenty four treatments and three replicates. The treatments were: three rates of Phosphorus (0, 600 and 1200mg P/5 kg soil), two rates of Zinc (0 and 20 mg Zn/5kg soil), two rates of Copper (0 and 15mg Cu/5kg soil) and two rates of Molybdenum (0 and 2mg Mo/5kg soil). The plants were harvested 65 days after planting, dried on oven at 65°C and the following parameters were evaluated: tops dry matter weight, grain yield and P, Zn, Cu and Mo top plant concentrations. Dry matter weight and grain yield only significantly responded to P applications. The two highest P rates did not differ significantly. The P top plant concentrations significantly increased with increasing P rates and decreased with Zn rates. The P applications caused a decrese in the leveI of the plant Zn. The P applications also decreased the leveI of Cu in the caupi top tissues. lt was verified no effects of the individuaIs applications of Zn and Cu on the tested plant nutrient concentrations. The Cambisol soil was able to satisfactorily supply the plant with the nutrients tested, except Phosphorus.