The co-planting between upland rice and cowpea production system is a way to create food security of highland communities. Meanwhile, a rhizobium in cowpea’s nodule plays an important role in the nutrient circulation of these plants.
First year, the aim of research is to evaluate the beneficial of microbial inoculation to cowpea (Vigna unguiculata) for improving upland rice productivity. The experimental design was divided two major pot experiments which conducted under the plastic greenhouse and used sterile soil from highs-land. The first experiment was the response of three varieties of cowpea (line 14 41 and 55) on rhizobium and AMF. The experiment was split into three sub-experiments according to varieties. Each variety had 6 treatments as follows:treatment 1 was no inoculation, treatment 2 was inoculated with root nodule bacterial (R) isolate 14/3 41/3 and 55/5 of each cowpea’s varieties (R), respectively. Treatment 3, 4 and 5 was inoculated both of rhizobium and AMF (AMF1, AMF2, and AMF3, respectively) from Thung Roeng Royal project. The treatment 6 was inoculated both of rhizobium and AMF4 form department of agriculture. The completely randomized design (CRD) with 4 replications was used. The second experiment was to study AMF1 AMF2 AMF3 and AMF4responsive on two varieties of upland rice (Luempua and Sew Mae Jan). The control treatment was no inoculation. The experiment was conducted using 2x5 factorial in CRD with 4 replications. Treatment as follows: treatment 1 was no AMF inoculation, treatment 2-5 were inoculated with AMF1, AMF2, AMF3 and AMF4 respectively. The result was found that the single inoculation of root nodule bacterial treatment increased the dry biomass of the above ground part of 14, 41 and 55 cowpea (14, 45 and 28 %, respectively) was higher than the control treatment (P<0.01). The 14 and 41 cowpea line, single inoculation of root nodule isolated bacterial was also increased the amount of fixed nitrogen higher than the control treatment about 70 and 47%, respectively. On the other hand, the 55 cowpea line, root nodule bacterial inoculation did not increased the amount of fixed nitrogen compared to the control. Both of inoculation of AMF (AMF1, AMF2, AMF3 and AMF4) and root nodule bacteria did not significantly affect on the percentage of root colonization compared with control treatment and did not change the phosphorus uptake of each cowpea line. The 14 cowpea line, both of inoculation of rhizobium isolated (R) and AMF treatments was reduced the amount of fixed nitrogen compared with the control treatment. In contrast, the 41 and 55cowpea lines were increased the amount of fixed nitrogen compared with the control treatment (R+AMF2, R+AMF3 and R+AMF4 for 41 cowpea line and R+AMF3 for cowpea 55 line). The results showed that Luempua and Sew Mae Jane rice varieties were different for the response to AMF inoculation on plant height and number of tillers per hill. The plant height of Luempua rice was higher than the Sew Mae Jane rice. The Sew Mae Jane was significantly responded to all AMF groups while Luempua rice was responded to AMF1 only. All of the AMF inoculation treatment was significantly improved the number of tillers per hill for both of upland rice varieties.