Composições poliméricas a base de carboximetilcelulose (CMC) e amido como veículos de inoculação de rizóbio em leguminosas

Abstract

This study had the objective of evaluating the efficiency of carboximethylcelullose (CMC) and starch based blends as carrier material of rhizobia to cowpea. Two tests were conducted to evaluate the survival of BR 3267 strain of Bradyrhizobium japonicum incubated at room temperature in compositions in the proportions of M1; M2; M3; M4 e M5 (CMC/Starch) compatibilizated with ZnO and MgO or not compatibilizated. The compositions M3 and M4 compatibilizated and the noncompatibilizated with 1% of ZnO and MgO showed capacity to sustain high bacterial populations till the 30th incubation day. It was established an experiment with these blends and with peat based inoculant, to evaluate the survival of rhizobial cells by a period of 12 weeks. The compositions compatibilizated with ZnO, were not capable to maintain high cells concentrations till the end of the incubation period. However the CMC/Starch/MgO compatibilized blends showed capable to sustain high bacterial populations (above 109 cells per mL) through the experiment time, being statistically the same as the peat based inoculant. Cowpea seeds pre-pelletizated were maintained in refrigeration to evaluate de capacity of maintenance of the cells inoculated, during a period of 8 weeks, using the same compositions used in the last experiment. In all the treatments, the seeds received a number of cells above 106 cells per seed, but they were not capable of maintaining a high cell number (above 6 x 105), during a period up to 5 weeks, suggesting that it is necessary to adequate the composition to this purpose. An assay in greenhouse conditions was made to evaluate the efficiency of polymeric blends as a delivery system of rhizobial cells to cowpea plants. All the treatments that used as carrier the polymeric blends were statistically equal to the treatments with peat based inoculants. This result shows that the rhizobial inoculants developed with the carrier based on polymeric blends using CMC and Starch are capable to produce the same performance, when compared with methods traditionally used for the inoculation of rhizobial cells to leguminous seeds. Thus, it is possible to develop a polymeric based inoculant to the inoculation of rhizobial cells to legume seeds.