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Subject: Crop Physiology × Author: Chack, Sonbeer × End date: 2017 × Start date: 2015 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    PHYSIOLOGICAL CHARACTERIZATION OF SOME WHEAT GENOTYPES FOR HIGHER NITROGEN USE EFFICIENCY AND YIELD POTENTIAL IN ASSAM
    (AAU, Jorhat, 2017-09) Chack, Sonbeer; Bharali, B.
    Wheat is one of the most important cereal crops globally, and is a staple food for about one-third of the world’s population (Hussain et al., 2002). Nitrogen is the most important yield-limiting nutrient for crop production in the world (Huber and Thompson, 2007). Two field experiments were conducted for two consecutive years near Stress Physiology Laboratory, Department of Crop Physiology, Assam Agricultural University. The main objective of the study was to characterise some wheat genotypes (collected from East Zone of India) physiologically for higher nitrogen use efficiency (NUE) and yield potential in Assam. In the first year experiment (November, 2014-April, 2015): Nitrogen @ 0, 50, 100, 150 kg ha-1 (as Urea) in the form of granules @ 50% of N as basal with the whole recommended doses of P (as Single super phosphate) and K (as Muriate of potash), and the rest 50% Urea were applied at maximum tillering stage. In the second year experiment (November, 2015-April, 2016), Nitrogen @ 0, 500, 1000, 1500 ppm (equivalent to granules in kg ha-1) were applied as foliar spray at the maximum tillering stage (once in a week for two weeks) of the crop. In the first year experiment, the varieties having the higher NUE in leaves were Wheat 231 (11.36%)> HP 1744 (8.58%)> Pusa Gold (8.42%), and higher NUE in seed were Wheat 231 (19.41%)> HP 1744 (10.01%)> Pusa Gold (9.29%)> PBW 343 (8.27%)> HD 2967 (6.08%). The physiological parameters contributing to the higher NUE in the varieties were maximum Leaf area in Wheat 231(16.81, 17.55 cm2 plant-1)> HD 2967 (15.11, 16.98 cm2 plant-1) at maximum tillering and PI stages respectively. The maximum leaf number was observed in wheat 231 (23.27)> HP 1744 (21.53)> PBW 343 (19.43) under the highest dose of N i.e. 150 kg ha-1 at panicle initiation stage. The other physiological parameters viz. root length of Wheat 231 (12.77 cm)>Pusa Gold (12.57 cm), root volume of Wheat 231 (10.31 cc)> PBW 343 (8.43 cc), and shoot dry weight of Wheat 231 (1.66 g)> HP 1744 (1.55 g) were responsive to augment NUE in the wheat varieties. The variety Wheat 231 (36.18, 34.26)> HP 1744 (33.19, 33.60) showed the highest NR activity (nmol NO2- g-1 fw of leaf) at both Maximum tillering and PI stages. Wheat 231 also exhibited higher N contents in leaf (0.41%) at PI stage, in grain (0.61%), and in leaf (0.37%) at harvest. The yield and yield attributes for higher NUE in the variety Wheat 231 were number of seed spike-1 (48.73), spike length (12.72 cm), spike weight (4.01 g), test weight (45.67), economical yield (3.02 t ha-1) and harvest index (47.32%). Nitrogen @ 150 kg ha-1 imparted higher NUE in leaves (12.48%) and grain (15.79%). In this contest, the physiological & biochemical parameters were leaf number (22.45), leaf area (18.30 cm2), root volume (8.41cc), NR activity (34.08 nmol NO2- g-1 fw of leaf) at PI stage, and starch content in leaf (271.05 mg g-1 d.w.) at maximum tillering stage, total N uptake (37.50%) and N content in seed & leaf (0.46%, 0.38%) at harvest as compared to values in controlled one. In the second year experiment, the varieties having the higher NUE in leaves were of Wheat 231 (10.90%)> HP 1744 (8.15%); and in case of seed, it was in Wheat 231 (18.74%) only. The physiological parameters contributing to the higher NUE in the variety Wheat 231 were: maximum leaf area (15.29 cm2 plant-1) at PI stage; root length (14.66 cm) at PI stage, NR activity (37.40 nmol NO2- g-1 fw hr-1) at maximum tillering stage, nitrogen content in leaf (0.456%) at PI stage and starch content in leaf (221.20, 241.22 mg g-1 d.w) at both maximum tillering and PI stages. The yield and yield attributes for higher NUE in the variety Wheat 231 were number of seed spike-1 (46.39), spike length (12.03 cm), test weight (44.00 g), economical yield (2.76 t ha-1) and harvest index (47.07%). The N dose @ 1500 ppm triggered higher NUE in leaves (12.07%) and grains (15.61%) at harvest. In this case, the other physiological & biochemical parameters contributing the higher NUE were leaf area (16.05 cm2), root length (14.39 cm), NR activity (19.08-37.69 nmol NO2- g-1 fw hr-1), N content in seed & leaf (0.493% & 0.394%) at harvest and nitrogen harvest index (0.56%) as compared to values in the controlled one. Overall, in the experiment 1, the variety Wheat 231 possessed the highest score (12) followed by PBW 343 (3)> Pusa Gold (1), and the variety HP 1744 & HD 2967 obtained zero score at harvest. In the second year, too, Wheat 231 (11) scored the highest followed by PBW 343 (3)> Pusa Gold (2)> HP 1744 (1), and the variety HD 2967 obtained zero score at harvest. Thus, it could be concluded that Wheat 231 emerged as the most physiologically efficient variety in the experiments. This variety possesses the adaptive traits, especially the higher NUE, yield and its attributes. Further, N-dose response studies revealed that N @ 150 kg ha-1 (as granule) or N @ 1500 ppm (as foliar spray) in the form of Urea was the most effective in augmenting the NUE and its related physiological indices including economic yield in wheat crop in Assam.