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Subject: Crop Physiology × Author: Borgohain, Eshani × End date: 2018 × Start date: 2018 × Type: Thesis ×
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    ThesisItemOpen Access
    RESPONSES OF SOME WHEAT (Triticum aestivum L.) GENOTYPES TO AEROSOLS OF NITROGEN
    (AAU, Jorhat, 2018-07) Borgohain, Eshani; Bharali, Bhagawan
    Wheat (Triticum aestivum L.) is one of the most important cereal crops globally, and it is a staple food for about one third of the world’s population. Cultivation of wheat has been the symbolic of green revolution that played pivotal role in making the nation a food surplus nation. The importance of wheat in Indian Agriculture is second to rice. The investigation into the effects of Nitrogen aerosols on some wheat (Triticum aestivum L.) genotypes (viz., 306, 1544, LOK-1, SHRI RAM-273), was accomplished both under field (October, 2016-March, 2017) and pot culture (October, 2017-March, 2018) at ICR farm and at the vicinity of Stress Physiology Laboratory, Department of Crop Physiology, Assam Agricultural University, respectively. The main objective of the investigation was to evaluate the physiological traits in wheat fertilized with Nitrate aerosols under field condition. The study, too, looked into the action mechanism of Nitrogen aerosol altering the physiology of wheat crop, and the relations between economic yield, physiological attributes and nitrogen status of wheat crop under the influence of aerosols. Treatments were applied at three stages viz., seedling, maximum tillering and spike initiation stages. The aerosols @ 400 ppm (≈40 kg N ha-1), were applied in three times i.e. 1200ppm or 1.2% (on sunny days in the afternoon (after 2–3 P. M.) when air temperature was low. In the field experiment, at maximum tillering and spike initiation stages, almost all the Nitrogen aerosols as compared to control increased the parameters significantly in a range viz., leaf area (8-13%) and (6-15%), LAI(19-31%) and (25.08-31.43%), SLW (11-26%), tiller numbers (14-28%) and (16-24%), effective tillers (19-31%), plant height (3-6%), rate of Pn (9-19%) and(10-16%), total chlorophyll content (14-34%) and (19-31%), chlorophyll a content (16-45%) and (23-35%), chlorophyll b content (14-33%) and (17-29%), NR activity (12-25%) and (23-36%), lipid peroxidase (6-53%) and (2-9%), CMS (14-28%), total carbohydrate content (18-28%), N content in grains (18-37%), NUE (26-39%), intercellular [K+] (13-31%), exchangeable [K+] (14-32%), intercellular [Ca2+] (11-28%) and exchangeable [Ca2+] (8-17%). The aerosols also increased the yield attributes such as no. of seeds per spike (2-7%), length of spike (14-24%), spike weight (14-18%), test weight (4-10%), harvest index (1.23-5.38%), biological yield (2-3%) and economical yield (3-8%). However, CMS was reduced non-significantly as compared to control at spike initiation stage. In the pot experiment, too, as compared to control, almost all the Nitrogen aerosols increased the parameters significantly in a range at maximum tillering stage and at spike initiation stages, respectively viz., leaf area (8-14%) and (4-10%), LAI (11-25%) and (11-21%), SLW (11-20%), tiller numbers (12-21%) and (10.68-16.66%), effective tillers (14.83-21.25%), plant height (5-8%), rate of Pn (16.78-23.43%) and (18-24%), total chlorophyll content (22-39%) and (26-33%), chlorophyll a content (22-43%) and (34-41%), chlorophyll b content (22-37%) and (23-30%), NR activity (14-28%) and (7.39-14.26%), lipid peroxidase (4-16%) and (2-9%), CMS (12-42%) and (12-26%), total carbohydrate content (7-16%), N content in grains (18-39%), NUE (25-42%), intercellular [K+] (21-44%), exchangeable [K+] (8-18%), intercellular [Ca2+] (7-24%) and exchangeable [Ca2+] (11-21%) . The aerosols also increased the yield attributes such as no. of seeds per spike (2-6%), length of spike (12-22%), spike weight (7-15%), test weight (5-9%), harvest index (2-7%), biological yield (2-7%) and economical yield (6-11%). In the field experiment, the variety LOK-1 possessed the highest score (25) followed by SHRI RAM-273 (10), and 1544 and 306 (2) considering their responses to the aerosols at maximum tillering, spike initiation and harvest stages. In the pot experiment, the variety LOK-1 possessed the highest score (28) followed by 1544 (4), SHRI RAM-273 (3) and 306 (2). However, based on the overall performance of the varieties at field and pot experiments together, the variety LOK-1 possessed the highest score (53) followed by SHRI RAM-273 (13), 1544 (6) and 306 (4). Thus, it could be concluded that the variety LOK-1 emerged as the most physiologically efficient one in the experiments. The physiological characteristics supporting the holistic performance of the variety LOK-1 especially are higher leaf area (12.90 cm2 plant-1) and (16.92 cm2 plant-1), LAI (1.63) and (0.99), effective tillers (2.69) and (3.89), rate of net photosynthesis (8699.76 ppm CO2 absorbed g-1d.w.h-1) and (9042.73 ppm CO2 absorbed g-1d.w.h-1), total chlorophyll content (2.48 mg g-1 fw of leaf) and (2.59 mg g-1 fw of leaf), chlorophyll a content (0.73 mg g-1 fw of leaf) and (0.80 mg g-1 fw of leaf), chlorophyll b content(1.68mg g-1 fw of leaf) and (1.73 mg g-1 fw of leaf), nitrate reductase activity (17.21 nmol NO2- g-1 fw of leaf hr-1) and (33.16nmol NO2- g-1 fw of leaf hr-1), CMS (0.17) and (0.65), carbohydrate content (147.63 mg g-1 dw) and (144.84 mg g-1 dw), intercellular [K+] (0.98 mg g-1 fw) and (1.07 mg g-1 fw), exchangeable [K+] (2.03mg g-1 fw) and (1.97 mg g-1 fw), intercellular [Ca2+] (1.66 mg g-1 fw) and (1.61 mg g-1 fw), exchangeable [Ca2+] (8.28 mg g-1 fw) and (8.28 mg g-1 fw), length of spike (10.78 cm) and (11.02 cm), spike weight (1.63 g) and (1.83g), test weight(47.15 g) and (4.57g), harvest index(69.42) and (51.57), biological yield (1.43 t ha-1) and (10.13 g plant-1) and economical yield(0.99 t ha-1) and (5.23 g plant-1) for field and pot respectively. Further as regard to the field application of N aerosols, KNO3 scored the highest (26) followed by Ca(NO3)2 (7), NH4NO3 (5), Control (0) considering the overall scores at maximum tillering, spike initiation and harvest stages. Similarly, in the pot experiment, KNO3 scored the highest (23) followed by Ca(NO3)2 (10), NH4NO3 (4), Control (0). However, based on the overall performance of the varieties at field and pot experiments together, the treatment KNO3 scored the highest (49) followed by Ca(NO3)2 (17), NH4NO3 (9), CONTROL (0). The correlation studies revealed that seed yield in LOK-1 was positively correlated with length of spike (0.63*, 0.97**), spike weight (0.69*. 0.09), harvest index (0.88**, 0.74*), biological yield (0.89**, 0.94*) and N content (0.80**, 0.94**) both for field and pot experiments respectively. In case of aerosol treatments, KNO3 was positively correlated with length of spike (0.97**, 0.55), test weight (0.88**), harvest index (0.96**, 0.79*), biological yield (0.78*, 0.76*) and N content (0.93**, 0.79*) at P (0.05)/ and P (0.01).