Crescimento da bananeira nanica (Musa sp.) sob diferentes qualidades de água de irrigação.

Abstract

The present study had as objective to study the effects of different levels of salinity and water types on the growth of the banana tree and the chemical characteristics of the soil. The work was carried out under greenhouse conditions using a sandy-texture eutrophic alluvial soil and using a completely randomized experimental design in a factorial scheme with 4 replicates. Two water types (predominantly bicarbonated or chlorinated) and four salinity levels (concentrations of 2, 10, 25, and 40 meq / 1) were prepared by adding appropriate volumes of NaHCO 3, CaCl 2, MgCl 2 and NaCl in water (2meq / l), maintaining the ratio of 7: 3 or vice versa between HCO3 and Cl and the ratio of 7: 1, 5: 1,5 between Na, Ca and Mg, respectively. The banana seedlings were planted in plastic containers (32x16cm) containing 16kg of soil and irrigated with the respective water for 150 days. At monthly intervals, the volume of water used in the irrigations was adjusted in such a way as to allow leaching equivalent to 10% of the water used in the period. The results showed that banana growth was not significantly affected by the water types used, however, for salinity levels there were significant reductions in all studied variations (plant height, pseudocaule diameter, leaf areas and dry weights of aerial and root portions) and the most drastic effects were observed at concentrations of approx. 25 meq / l. Among the variables studied, root weight was the most affected by salinity levels, showing a reduction of up to 93% in the treatment with 40 meq / l, in relation to the control. The salinity of water, in addition to reducing the size of the leaf, caused a delay of up to 8 days in its full opening. As for the content of the elements (N, P, K, Ca, Mg, S, Mn, Fe, Cu, Zn, Na and Cl) at 150 days, water types had only significant influence on Na and Cl, while the levels of salinity. The water volumes used by the banana tree were negatively influenced by the salinity levels. In treatments irrigated with water from 10 meq / l the leaves became chlorotic and / or necrotic, with more drastic effects in the saline treatments and in larger proportions in the bicarbonated waters. Soil analysis, after experiment, revealed a significant accumulation of salts in the treatments with concentration from 10 meq / l and in higher proportions in the chlorinated waters.