Nodulation, nitrogenase activity, and dry weight of chickpea and pigeon pea cultivars using different Bradyrhizobium strains

Chickpea [Cicer arietinum (L.)] and pigeon pea [Cajanus cajan (L.) Millsp.] were grown outside in large clay pots from 1992 to 1995 in Edmond, Oklahom a. Plants were studied to evaluate nodulation, nitrogenase activity, and sh oot dry weight (DW) of 'ICCV-2' and 'Sarah' chickpea inoculated with multis train, TAL 1148, and TAL 480 Bradyrhizobium, as well as 'Georgia-1' and 'IC PL-87', pigeon pea inoculated with multistrain TAL 1127, and TAL 1132 Brady rhizobium. Following wheat [Triticum aestivum (L.) emend. Thell.] harvests in the spring, legumes were planted in the summer and harvested at three su ccessive dates during the following months. Leaves and stems fi om remainin g plants were incorporated into the soil after the last harvest. Across yea r, chickpea measurements were sensitive to temperature and precipitation wh ereas pigeon pea measurements were sensitive to length of growing season as well as climate. Pigeon pea consistently demonstrated higher nitrogen-fixi ng capacity and shoot DW compared with chickpea. Nodule and shoot DW of bot h species increased with plant age whereas nodule count and nitrogenase act ivity generally increased with plant age and leveled off or decreased at fl owering. Sarah chickpea demonstrated higher nodule count and nodule DW than ICCV-2, as did the Georgia-1 pigeon pea compared with ICPL-87. Shoot DW of Georgia-1 pigeon pea was generally higher than that of ICPL-87. Multistrai n inoculum improved nodulation and shoot DW of chickpea, and TAL 1127 impro ved nodulation of pigeon pea compared with other treatments. These results indicate that specific chickpea and pigeon pea cultivars, along with approp riate Bradyrhizobium strains, may improve nitrogen fixation and DW of these species.