Viabilidade do cultivo de caupi (Vigna unguiculata (L.) Walp.) em áreas com problemas salino-sódicos.

Abstract

Aiming to study the cultivation of Vigna in soil presenting problems of salinity, this study was carried out in an irrigated area with a central pivot at Escola Agrotécnica Federal de Sousa / PB, in the Irrigated Perimeter of São Gonçalo. Initially, a mapping of the CE levels, of the experimental area, was carried out. From this initial survey, 26 points are located, located in sub-areas, named 1, 2 and 3, with salt levels varying from CEcs 0.49 to 2.99 dS.m-1. The minimum and maximum PST values ​​observed were 2.76% and 82.66%, respectively. Under these conditions, the cowpea crop, variety EPACE-10, was installed, 26 plants were monitored in the places where the soil samples were collected, in the Ires sub-areas. The irrigation management was carried out with soil moisture control (neutron probe), seeking to maintain the minimum moisture content required by the crop, without prejudice to the production. After the harvest. soil samples were collected at the same locations where the plants were monitored in order to understand the dynamics of the soil variables under study, CE, PST and pH. There was an increase in CE values. in the three sub-lines. in which initial ranges went from 0.49- 1.01 to 2.07-2.99 dS.m-1 (sub-bar 2); from 0.93-1.97 to 2.00-3.99 dS.m-1 (sub-row 3). In sub-row 1, modifications of lower amplitude, raised the upper limit of the range from 1.16 to 1.24 dS.m-1, however, there was a lowering of the lower limit from 0.63 dS.m-1 to 0.59 dS.m "\ There was a decrease in PST and an increase in exchangeable Ca" c Mg **. There was a tendency to lower the pH in places with sodicity problems, however, the final values ​​still remained at levels high, compatible with the highest PST values. Number of leaves, leaf area, dry matter of leaves, number of branches, dry matter of branches, number of pods, dry matter of grains and relative crop production were used for development and production evaluation. Saline EC levels below 1.2 dS.m-1 and PST values ​​below 4.5%. characterized the sites with plants that obtained the highest yields. Initial PST values ​​in the range of 5 to 13%. associated with EC values ​​of up to 1 dS.m-1 promoted a reduction in all indexes (by an average of 27.77%). the reduction of the leaf area being more accentuated (32.29%) and less accentuated in the dry matter of branches of branches (19.95%). Initial PST values, from 20.16% to 82.66% and EC ranging from 1 to 3.46 dS.cm-1 promoted a drastic reduction in the development and production of culture (70%. cm average) for all evaluated parameters. In this case, the least affected was the number of leaves that was reduced by 63.1% and the most affected was dry grain matter, with a reduction of 84%. Regression analyzes (multiple and exponential) were performed using values ​​of CE and PST, resulting in satisfactory mathematical models to describe the interferences of these parameters in plant development and production.