Sharma, PushpBajya, Mamta2023-12-122023-12-122023Mamta Bajya (2023). Effect of growth retardant to hasten maturity in groundnut (Arachis hypogaea L.) and utilization of phosphorous solubilizing bacteria to enhance its phosphorous uptake (Unpublished Ph.D. Dissertation). Punjab Agricultural University, Ludhiana, Punjab, India.https://krishikosh.egranth.ac.in/handle/1/5810202759The preliminary field experiment was conducted on SG99 to test the efficacy of growth retardant mepiquat chloride at five concentrations (100,300,500,700 and 900ppm) keeping check as control. Single foliar spray of mepiquat chloride was given at 40, 60 and 80 DAS. Results of preliminary field experiment revealed the effective concentration of growth retardant was 700 ppm and the time of foliar spray selected was between 45-50 days after sowing. Therefore two foliar sprays were given first at 50 DAS followed by second spray 10 days thereafter (60 DAS) on three released varieties of groundnut (SG99, TG37A and J87) during the two consecutive kharif seasons (2020 and 2021) significantly reduced days to maturity days, plant height but increased number of branches, nodule number and weight with mobilization of assimilates to the developing sinks as per source sink relationship .Overall, mepiquat chloride@700 ppm improved physiological and biochemical traits along with an increased number of mature pods and decreased immature pods, resulting in enhanced pod (14.6%) and kernel yield(21.4%) in kharif .Similarly an increase of 19.6% in pod yield and 24.3% in kernel yield was witnessed in spring season. Kernel treated with different microbial inoculants showed differential responses to RWC, membrane stability, leghaemoglobin content, nodulation, however with Azotobacter increase in enzymatic activity was almost similar over control at two doses of P2O5 i.e.16.5% for nitrite reductase and almost 5.0% .for nitrate reductase. Strong relationship between source-sink existed with Azotobacter inoculations for two phosphorous doses at 100DAS. Pod yield improved by 19.7 % with Azotobacter double dose and P uptake in kernels. Pod yield improved by 17.4%, shelling percentage by (6.6%), kernel yield by 25.2 % and 100 kernel weight by 11.9% with combined treatment of Azotobacter + mepiquat@700 ppm over control. The photosynthetic pigments and enzymatic activities enhanced with this beneficial treatment.EnglishThesis