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Subject: Crop Physiology × Start date: 2019 × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    PHYSIOLOGICAL PERFORMANCE OF RAPESEED (Brassica rapa var. Toria) GENOTYPES UNDER RAINFED CONDITION OF ASSAM
    (2023) CHINTEY, RAJESH; Goswami, Ratna Kinkor
    The present research work entitled “Physiological performance of rapeseed (Brassica rapa, var. Toria) genotypes under rainfed condition of Assam” was carried out at the Instructional-cum-Research (ICR) Farm, Assam Agricultural University, Jorhat-13, Assam during rabi seasons of the years 2021-22 and 2022-23. The main objectives of the study were to find out the suitable superior genotypes based on the physiological efficiency and to identify the parameters which contribute significantly towards yield improvement in rapeseed. The field experiment was laid out in randomized block design with three replications comprising of 22 different genotypes of rapeseed including TS-38 (Check), TS-46, TS-67, TS-36, TS-29, TS-75-1, TS-75-1TL, TS-75-2ME, TS-75-2-MM, TS-76-1, TS-76-2, JT-90-1, Panchali, Bhawani, CG Toria-4, TKM-20-1, TKM-20-2, JT-14-5, PT-2018-09, CG Toria-3, Tapeshwari and PT-303. The crops were grown following the recommended package of practice. All the morpho-physiological, biochemical, quality parameters, yield attributes and yield of the crops were taken following the standard methodologies. The results of the study indicated a significant variation of all the morpho-physiological, phenological, quality parameters, yield attributes and yield among the genotypes. The genotypes, TS-75-2ME, TS-38, PT-303 and TS-36 exhibited morpho-physiological superiority with regard to more number of branches, stem diameter, accumulation of more photosynthates, more AGR, CGR and leaf chlorophyll. The same genotypes also recorded significantly higher yield attributes and seed yield. The correlation studies also showed a significant positive correlation of these parameters with seed yield in the set of the genotypes, indicating clearly that these parameters may be regarded as morpho-physiological indices for improving crop productivity in rapeseed. From the results, the genotypes, TS-75-2ME, TS-38, PT-303 and TS-36 may be regarded as superior genotypes suitable for growing under rainfed condition during rabi season in Assam and North-Eastern states of India and may be used as genetic sources in further yield improvement programme of rapeseed.
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    ThesisItemOpen Access
    STUDY ON DIVERSITY OF RICE IN NAGALAND AND THEIR SUITABILITY TO CHANGING CLIMATE
    (AAU, Jorhat, 2022) Merentoshi; Das, Ranjan
    The present investigation was carried out during the year 2018 to 2020 to evaluate the performance of some rice (Oryza sativa L.) genotypes from Nagaland under different CO2 and temperature regimes viz., Treatment I = Field (control), treatment II = (CO2 (550±20ppm) + Temp. of 40 C > ambient) and Treatment III = CO2 (750±20ppm) + Temp. of 60 C > ambient) under fully automated bioreactors with CO2 and temperature control facilities in Stress Physiology Laboratory, Department of Crop Physiology, Assam Agricultural University, Jorhat-13. In the first experiment, 75 rice genotypes collected from different locations of Nagaland were subjected for initial screening for tolerance against elevated CO2 and temperature out of which 7 genotypes were selected for further study on their response mechanism of tolerance by comparing with the national check variety N22. The results revealed that treatment II had a positive impact on the various morpho-physiological parameter viz., plant height, number of leaves, leaf area index, root volume and length, membrane stability index, total leaf chlorophyll content, leaf nitrate reductase activity, proline in all the genotypes whereas a declining trend indicating the deleterious effect of high temperature, at a higher CO2 and temperature in treatment III was observed in all these parameters. Similarly, significant variation in photosynthesis and its related parameters (viz. stomatal conductance, internal CO2, transpiration) affected the photosynthetic rate and their partitioning to root, shoot and reproductive organ under both the treatments as compared to field condition. These factors ultimately contributed to growth efficiency and yield of the plant. Amongst the treatments, significant increase of H2O2, MDA content was recorded in treatment III as compared to treatment III. Kohima Special and N22 recorded lower H2O2 and MDA when compared to other local genotypes. Hence these two genotypes could maintain their plant water status as evidenced by their higher MSI under both the treatments. The maintenance of higher plant water status in Kohima Special and N22 could be attributed to their higher RLWC and increased compatible solutes viz. proline content and non structural carbohydrate contents. Further, studies in tolerance indices indicated that among the tested local genotypes, Kohima Special and Lisem were tolerant whereas Tatza and Tzumma showed to be most susceptible under high temperature. In the molecular analysis, using SCoT molecular markers out of 77 bands amplified, 55 were found to be polymorphic with 68.99 per cent polymorphism. Only four primers SCoT28 and SCoT34 not found to be polymorphic alleles, while remaining 23 SCoT primers showed both polymorphic alleles. Yield and yield attributing characters are governed by all the morphological, physiological and biochemical processes. Among yield parameters, 1000-grain weight, spikelets per panicle and total grain weight per plant were significantly higher due to elevated CO2 at treatment II since the genotypes could maintain a higher photosynthetic rate and had a superior plant defence mechanisms but were significantly decreased under high temperature at treatment III which was negatively influenced by all the processes resulting in decrease in yield and yield attributing characters in all the genotypes.
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    ThesisItemOpen Access
    PERFORMANCE OF SOME BANANA GERMPLASM UNDER MOISTURE STRESS CONDITION AND ITS AMELIORATION THROUGH CHEMICAL INTERVENTION
    (AAU, Jorhat, 2020-07) Saikia, Amarjit; Kalita, Prakash
    A study was conducted at the Experimental Farm, Department of Horticulture and laboratories of Department of Crop Physiology, Assam Agricultural University, Jorhat during the period 2017-2019 with twenty nine germplasm of banana viz., Athiya (BB), Manohar (ABB), Dwarf Jahaji (AAA), Barjahaji (AAA), Ketchulepa (ABB), Jatikal (ABB), Kachkal (white) (ABB), Kachkal (green) (ABB), Honda (AAB), Gobin Tulchi (AAB), Doodhsagar (AAB), Digjowa (AAB), Chenichampa (AAB), Malbhog (AAB), Amrit Sagar (AAA), Man Jahaji (AAA), Agnisagar (AAA), Bhimkal (BB), Lesari Manohar (ABB), Simolu Manohar (ABB), Suti Jahaji (AAA), Bhat Manohar (ABB), Sahabhal (AAA), Fesa manohar (ABB), Dwarf Cavendish (AAA), Grand Naine (AAA), Bogimonohar (ABB), Odil (AAA) and Thengransu (ABB) to assess their performance under moisture deficit condition that prevails naturally during November to January every year in Assam due to lack of rainfall. The germplasm were also evaluated for any change in their tolerance level towards soil moisture deficit after receiving certain chemicals viz. maltose and trehalose through foliar spray. The experiment was laid out in Randomized Block Design (RBD) with twenty nine germplasm. The number of replications was five. The observations on various parameters were recorded on 3rd, 5th, 7th and 9th MAP in the main crop and one month after application of chemicals in the case of ratoon crop. The mean monthly temperature during the crop growing season ranged from 10.8°C to 29.8°C, the rainfall ranged from 0.0-42.7 mm and the relative humidity ranged between 55-97 per cent. The soil of the experimental field was acidic, well drained and sandy loam in texture with low available N and K and medium available P content. Moisture stress progressively reduced the values of relative leaf water content, leaf area, leaf area index, chlorophyll content (a, b, & total) from 3rd to 9th months after planting; while the contents of proline, total soluble protein, free amino acid and level of lipid peroxidation in leaf tissue increased with increase in the magnitude of moisture deficit during that period. Germplasm viz., Barjahaji, Bhimkal, Athiya etc. recorded higher values for various physiological and biochemical parameters namely relative leaf water content, proline content, total soluble protein content, free amino acid content, leaf area, leaf area index, leaf chlorophyll content, number of functional leaves etc. especially during the period when the soil moisture content was very low. Observed higher efficiency in terms of physiological and biochemical parameters in these germplasm might have contributed immensely 6 towards realisation of better yield attributing characters like fruit length, girth of finger, volume of finger weight of finger, weight of second hand, number of hands per bunch, number of fingers per hand and bunch weight under Assam condition which faces severe shortage in soil moisture (soil moisture content was only 33.70 per cent of the field capacity at 7th MAP) under rainfed situation during the months of winter mostly coinciding the reproductive stage of the crop. The germplasm Barjahaji was found to be the highest yielder followed by the germplasm Bhimkal and Athiya, whereas Gobin Tulchi was found to be the lowest performers. It may be concluded that the germplasm Barjahaji, Bhimkal and Athiya are physiologically more tolerant to moisture shortage. Application of chemials (trehalose and maltose) could positively influenced various adaptive mechanism during water deficit condition. The characters like relative leaf water content, proline content, total soluble protein content, free amino acid content, chlorophyll content, leaf area, leaf area index etc. did show positive and significant correlation with bunch yield per plant. On an average with foliar application of maltose (60 mM), trehalose (60 mM) and maltose (60 mM) + trehalose (60 mM) during December, increased the yield by 1.18, 1.76 and 2.44 per cent, respectively over control (spray with distilled water). The highest benefit: cost ratio in case of dwarf germplasm, medium tall germplasm and tall germplasm were found to be 4.66 (Dwarf Jahaji), 4.39 (Barjahaji) and 4.41 (Athiya) respectively all with distilled water spray.