Das, RanjanDoulboruah, Pronamee2023-12-302023-12-302021https://krishikosh.egranth.ac.in/handle/1/5810205194A field experiment was conducted at stress physiology laboratory, AAU, Jorhat during kharif season of 2020-2021 to study the “Nitrogen acquisition under elevated CO2 and temperature in rice (Oryza sativa L.). The experiment was carried out in controlled environment under CO2 temperature gradient tunnel (CTGT), to understand the differential response of rice to higher level of CO2 i.e. CTGT-I at ambient CO2 395 ppm & temperature, CTGT-II at elevated CO2 (550±20ppm) + temp. of 4 0 C > ambient and CTGT-III at elevated CO2 (750±20ppm) + temp. of 6 0 C > ambient with four different level of N treatment viz. N0 (zero N), N1 (75% recommended dose), N2 (100% of recommended dose), N3 (125%of recommended dose). The experiment was laid out in two factorial completely randomized block design (FCRD) with 10 replications. The popular rice cultivar of Assam, Luit, was collected from research station of Agricultural University. This experiment was conducted on pot which was sown on 8th Aug 2020 and harvested between 28th Nov to 2nd Dec 2020. In the experiment under elevated CO2 and temperature there was a significance difference of crop growth parameters where highest value were recorded at CTGT-II with N3. In phenological data highest value was recorded at CTGT-III with N3. All biochemical and anatomical parameters also exhibit better result in CTGT-II with N3 as compared to CTGT-I. Membrane related phenomenon i.e. MSI was recorded as high at CTGT-II with N3. But there was a negative trend in H2O2 and lipid peroxidation where highest value was recorded at CTGT-III with N0. Similar result also found in water relation parameters and all physiological parameters. Chlorophyll florescence related phenomenon shows highest result in CTGT-II at N3. Likewise, yield attributing parameters gave highest value in CTGT-II with N3. Results shows that application of N significantly increased various morphological growth parameters as well as yield parameters in rice under elevated CO2 condition (at 550±20 ppm with 40 c temperature) under CTGT-II as compared to CTGT-I and CTGT-III. High temperature has a deleterious effect on plant growth and some related processes viz. physiological and biochemical activities because an effect on C: N ratio. Therefore, supplementation of N may play a pivotal role in amelioration of some deteriorative process like lipid peroxidation content and MDA content of leaves thereby reduced yield by affecting yield attributing parameters. Results indicated that higher doses of N under elevated CO2 and temperature invariably maintained not only the C:N ratio but also improved the physiological response positively. But at lower level of N in plant showed poor plant growth as well as metabolic de-arrangement because of low photo synthetic rate, nitrate reductase activity, chlorophyll loss and depression membrane stability index. Therefore, modification of agriculture and nutrient management technologies for future environments is important criteria for sustainable management of rice ecosystem.EnglishThesis