Abstract
The study was conducted at the Bangladesh Agricultural Research Institute Farm, Joydebpur, Gazipur in both rabi and kharif seasons from November 1988 to October 1990 to find out the yield potential of groundnut with the use of Bradyrhizobium inoculant, mineral fertilizer and growth regulator. Three experiments were conducted with two varieties of groundnut Dhaka-1 and Zhingabadam.Zhingabadam did better than Dhaka-1 in respect of yield and yield components. The application of inoculant and fertilizer either individually or in combination enhanced the vegetative and reproductive growth of groundnut.Combined use of fertilizer was superior to individual one where the yield increase ranged from 13 to 31% in rabi season and 16 to 31% in kharif season. In rabi season, NPK+Inoc and in kharif season, PK+Inoc improved the plant characters and produced the highest pod yield in both the varieties. Groundnut produced lower pod yield in kharif than in rabi season due to high temperature in kharif season and inoculated groundnut did not require nitrogenous fertilizer.The growth regulators exerted positive response on the growth and development of groundnut. The yield potential varied from 5 to 12% in rabi and 2 to 19% in kharif season over control. The highest yield was recorded in Planofix and 2,4-D in both the varieties irrespective of seasons. The application of 2 ppm of Mixtalol produced the highest yield of groundnut in both the seasons.It was observed from the integrated use of growth regulator, Bradyrhizobium inoculant and fertilizer that both the varieties showed improved plant growth characters such as DM, LAI, NAR, CGR, RGR, nodule/plant, dry weight of nodule and shoot/plant. Plant height was higher in kharif than in rabi season due to high temperature. On the other hand, both the varieties showed higher performance in respect of mature pods/plant, 100 seed weight, pod yield/ha and oil content in rabi than in kharif season.In both the seasons, Zhingabadam produced more pod yield/ha than Dhaka-1. Seasonal yield variation was more in Dhaka-1 than Zhingabadam.Growth regulators exhibited positive response on both vegetative and reproductive phases irrespective of seasons. They increased pod yield/ha by 5 to 6% in rabi and 6 to 12% in kharif season. The growth regulator 2,4-D enhanced the vegetative growth in rabi season and in the uptake of NPK by the plants in both the seasons. Mixtalol and Planofix were found to promote the vegetative growth in kharif season and yield of groundnut including sulphur uptake by the plants in both the seasons.Although all the growth regulators were good for groundnut production but Mixtalol was found more effective than 2,4-D and Planofix for yield attributes in both the seasons.The application of inoculant and mineral fertilizer either individually or in combination enhanced the vegetative growth i.e. DM, LAI, NAR, CGR, RGR, plant height, number of branch/plant, nodule/plant, dry weight of nodule/plant, shoot/plant and reproductive organs like mature pods/plant, 100 seed weight and pod yield/ha. Moreover, shelling percentage, harvest index, oil and protein content in the seeds and NPKS contents in the plants were influenced in both the varieties and seasons.Growth and development of groundnut was higher due to the combined use of Inoc and mineral fertilizer rather than individual use of fertilizer. The application of NPKS+Inoc in rabi and PKS+Inoc in kharif season resulted in the best performance of groundnut. Nodule/plant was higher in rabi season due to NPKS+Inoc and for NPK+Inoc in kharif season. The dry weight of nodule and shoot/plant was higher due to NPK+Inoc and was similar with NPKS+Inoc in both the seasons. Application of fertilizer increased pod yield/ha by 11 to 36% in rabi and 19 to 38% in kharif season over control. In rabi season, inoculated groundnut required a small quantity of nitrogen as starter dose for better production of crop, while in kharif season, inoculated groundnut did not require nitrogenous fertilizer. The use of sulphur @ 20 kg/ha increased pod yield/ha by 7% irrespective of seasons.
Most of the plant characters were affected due to the combined use of growth regulator and fertilizer. In rabi season, Mixtalol plus NPKS+Inoc increased the pod yield by 53% over control and in kharif season, Mixtalol plus PKS+Inoc exhibited increased pod yield/ha by 59% over control. In kharif season, Dhaka-1 with Mixtalol plus PKS+Inoc increased pod yield/ha by 61%, while in Zhingabadam the increase was 54% over control with the same treatment.
The use of growth regulator increased the pod yield by 5 to 12%, whereas with the inoculant the increase was 11 to 19% over control. With growth regulator plus inoculant the pod yield increase was 19 to 36% and the combination of growth regulator, inoculant and mineral fertilizer the increase was 36 to 59% over control.