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ThesisItem Restricted REGULATION OF SENESCENCE THROUGH THE APPLICATION OF PLANT GROWTH REGULATORS AND NUTRIENTS IN RELATION TO PRODUCTIVITY IN SOYBEAN (Glycine max L. Merrill)(Punjab Agricultural University, Ludhiana, 2010) Kaur, Jasdeep; Kaur, JagmeetSoybean called ‘Miracle Bean’ belongs to family Fabaceae, contains 40% proteins and 20% edible oil. A striking feature of maturing soybean is decline of assimilatory capacities due to growing reproductive structures and is characterized by syndrome of physiological changes that include decline in foliar N, protein, chlorophyll and photosynthetic activity culminating in leaf abscission. The regulatory signals exchanged between the parts of soybean plant during development are affected by endogenous levels of hormones and possibly nutrient fluxes. The exogenous application of plant growth regulators and nutrients was done to study the senescence behavior in soybean. The treatments comprised of control (no spray), foliar application of SNP @150 and 200 µM, ethrel @ 150 and 200 µgml-1, calcium chloride @ 1 and 2 mM and sodium selenite @10 and 20 µgml-1. The treatments were applied in combinations of three stages vis-à-vis preflowering (V), pod initiation (P) and grain filling (G). Various observations pertaining to the morpho-physiological, biochemical and yield attributes were recorded at various growth stages. The morpho-physiological traits vis-à-vis plant height, root length, leaf characteristics, canopy characteristics and biomass accumulation studied at 60, 80, 100 and 120 DAS; were effectively enhanced by V+P+G application of SNP 200µM and P+G application of sodium selenite 20µgml-1. Also, the application of SNP 200µM (V+P+G) and sodium selenite 20µgml-1 (P+G) gave best results in terms of yielding attributes viz. pod count, 100 seed weight and seed yield. The photosynthetic pigments and activity along with storage biomolecules (total soluble sugars and starch) exhibited maximum change with SNP 200µM (V+P+G) and sodium selenite 20µgml-1 leading to enhanced production of photosynthates and accumulation of photoassimilates. The activities of antioxidant enzymes vis-à-vis catalase, peroxidase and superoxide dismutase concomitant with proline accumulation was putatively enhanced with the application of SNP 200µM (V+P+G) and sodium selenite 20µgml-1 (P+G) thereby counteracting the senescence induced oxidative stress. Also, the treatment with SNP 200µM elicited the activation of high molecular weight proteins in the leaves at 80 DAS. Conversely, higher concentration of ethrel at all treatment combinations depicted reduction in morpho-physiological traits, intense loss of chlorophyll and membrane integrity, lesser production of sugars and starch and reduced antioxidants contributing towards much reduced yield. Therefore, NO donor SNP 200µM (V+P+G) and sodium selenite 20µgml-1 (P+G) behaved as anti-senescence growth substance.ThesisItem Open Access INFLUENCE OF BENZYLAMINOPURINE AND SALICYLIC ACID ON MORPHO-PHYSIOLOGICAL AND SOME BIOCHEMICAL PARAMETERS OF WHEAT (Triticum aestivum L.) UNDER WATER STRESS(Punjab Agricultural University, Ludhiana, 2010) RadhikaThe influence of Benzylaminopurine (BAP) and Salicylic acid (SA) on morphophysiological and some biochemical parameters of wheat (Triticum aestivum L.) genotypes (PBW 343 and PBW 527) under water deficit conditions was studied. The PEG (6000) induced water stress (-.2MPa, -.4MPa and -.6MPa) had markedly reduced the root and shoot traits (coleoptile length, seminal root number, seminal root length, number of leaves, total leaf area, seedling fresh weight and seedling dry weight) at 10 DAS under laboratory conditions. Foliar application of BAP and SA given at the 7 DAS had partially ameliorate the PEG induced water stress. Water stress given at the tillering stage and the boot leaf stage had significantly reduced the plant height, hill reaction activity, photosynthetic pigments, starch, proteins and significantly induced the sugars, free amino acids, proline, water saturation deficit, relative saturation deficit, acid invertase activity and membrane permeability in the leaves of the studied genotypes at both 70 DAS and 100 DAS. Water stress imposed at the tillering stage resulted in more yield loss as compared to the stress given at the boot leaf stage. Foliar application of BAP @100 μg ml-1 given at the vegetative stage under water deficit conditions had showed the stress ameliorative effect and foliar application of SA @ 30 μg ml- 1 given at the vegetative stage had more growth promotary effect as compared to the application given at the anthesis stage under water deficit conditions, whether the stress was given at the tillering stage or the boot leaf stage.ThesisItem Open Access ThesisItem Open Access SELECTION CRITERIA FOR COMBINING HIGH GRAIN YIELD AND PROTEIN CONTENT BASED ON NITROGEN PARTITIONING EFFICIENCY IN WHEAT (Triticum aestivum L.)(Punjab Agricultural University, Ludhiana, 2010) Sidhu, Sukhpreet KaurThis study was designed to identify selection criteria for the simultaneous improvement of grain yield and grain protein concentration in wheat (Triticum aestivum L.). Three wheat cultivars namely PBW-550, PBW-502 and PBW-343 were sown on 2nd week of November under two nitrogen levels (120 and 180 kg ha-1). Results showed that Cv.PBW-550 found to have maximum remobilization efficiency (78.98%), grain protein yield (90.33 g m-2) and nitrogen harvest index (0.602). This cultivar had higher grain yield (57.34 q ha-1) averaged over both nitrogen level due to maximum number of spikes per plant (7.5), number of kernels per spike (65.67) and 1000- kernel weight (44.43 g) as compared to Cv.PBW-502 and PBW-343.This indicate that Cv. PBW-550 expressed high levels of both traits concurrently. Pearson correlation analysis showed significant positive correlation with grain yield and vegetative nitrogen at anthesis + 12 days (r = 0.9693**), vegetative nitrogen at anthesis + 4 days (r = 0.8527**), accumulated nitrogen (r = 0.8596**), accumulated dry matter (r = 0.7313**) at post anthesis stage. Correlation analysis also indicate significant positive correlation between grain protein concentration (r = 0.8236**), harvest index (r = 0.9833**), total plant nitrogen (r = 0.9710**) and grain protein yield (r = 0.9067**) at physiological maturity. Regression line between grain yield and grain protein concentration showed significant positive relationship (R2 = 0.6948).The correlation and path analysis revealed that the direct effect of vegetative nitrogen at maturity was more (P9 11= 0.5329) followed by remobilization efficiency (P10 11=0.2072) on grain yield. The regression model showed significant positive correlation between grain yield and growing degree days accumulated during booting stage (R2= 0.4709).These results indicated that Cv.PBW-550 showed 12.96% increase in grain yield and 19.62% increase in grain protein concentration due to its high nitrogen remobilization and partitioning efficiency. Nitrogen uptake and nitrogen partitioning function as separate and independent physiological systems in wheat plants. Therefore, improvement in both grain protein percentage and grain yield realized by manipulating nitrogen uptake and its partitioning separately.ThesisItem Restricted Studies to moderate the heat stress effects on wheat (Triticum aestivum L.) productivity(Punjab Agricultural University, Ludhiana, 2010) Davinder SinghThe field experiment entitled “Studies to moderate the heat stress effects on wheat (Triticum aestivum L.) productivity” was carried out at Punjab Agricultural University, Ludhiana during 2009-10. Results of the investigation indicated that wheat yields in heat stress environment can be raised significantly by modifying agronomic practices. The sowing of 25 November gave significantly higher grain yield than late sowing of 10 December. The crop sown on 25 November with zero tillage in standing stubbles after removal of loose straw and one foliar spray of KNO3 (1%) during anthesis was at par in grain yield than those obtained with conventional tillage without mulching + two foliar spray of KNO3 (1%) during anthesis/one additional irrigation during post anthesis, conventional tillage with mulching + one additional irrigation during post anthesis/ recommended irrigation. It was significantly higher than the crop sown on 25 November and 10 December with other methods of planting and agronomic practices. When crop sown very late on 10 December gave the maximum yield with zero tillage in standing stubbles after removal of loose straw with one/two foliar spray of KNO3 (1%) during anthesis or one additional irrigation during post anthesis conventional tillage without mulching with two foliar spray of KNO3 (1%) during anthesis/one additional irrigation during post anthesis and conventional tillage with mulching with one additional irrigation during post anthesis which was significantly higher than crop sown 10 December with other methods of planting as well as agronomic practices. In heat stress environment the higher yield obtained from the crop sown on 25 November and 10 December with the modifying practices due to the higher growth, yield contributing characters, lower soil and canopy temperature and especially higher use of growing degree days and photo-thermal units by the crop sown on 25 November.ThesisItem Open Access SCREENING AND CHARACTERIZATION OF PHYSIOLOGICAL TRAITS IN WHEAT VARIETIES FOR NITROGEN EFFICIENCY(Punjab Agricultural University, Ludhiana, 2010) Sanghera, Amritpal KaurA field experiment was conducted at the research farm of Department of Soils Punjab Agricultural University, Ludhiana with an objective to screen wheat cultivars (cvs) for N efficiency and determine the physiological traits for N efficiency. Fifteen wheat cvs (10 bread wheat, 3 durum wheat and 2 triticale genotypes) were grown on soil low in available N at four levels of fertilizer N (0, 50, 100 and 150 N kg ha-1). On the basis of grain yield, N uptake efficiency (NupE), Biomass N utilization efficiency (BNutE) and Grain N utilization efficiency (GNutE), three bread wheats (PBW 509, PBW 502, PBW 343) were selected as efficient and three durum wheats (PDW 274, PDW 291 and PDW 233) as inefficient cultivars. Efficient cultivars had significantly higher grain yield, NupE and GNutE while BNutE was more in inefficient cvs. Grain yield had significant positive correlation (r = 0.973) with NupE. Normalized difference vegetative index at different stages was significantly higher in efficient cultivars and had positive correlation with grain yield both at low and high N. Root distribution in the profile indicated that roots of efficient cvs penetrated into deeper layers compared to inefficient cvs which had denser root system but only in the surface layers. Nitrate reductase activity had a negative correlation with grain yield (r = -0.93) and NupE (r = -0.92) but positive correlation with BNutE (r = 0.73), suggesting that this enzyme cannot be used as index of N efficiency in wheat genotypes. Efficient cultivars had higher number of leaves and tillers, total N uptake and dry matter production than inefficient cvs. Grain yield and GNutE had positive correlation with N partitioning in grain (r = 0.75) but negative correlation with N partitioning in leaves (r = -0.77) and chaff (r = -0.76) under low N indicating that N mobilization from leaves and chaff to the grain limited grain yield and GNutE. Our study indicates the possibility of genetic modification for deeper rooting to increased N uptake, vegetative growth, biomass and grain production. Early flowering genotypes with grain filling period coinciding with favourable temperature are another characteristic of wheat development related to N efficiency.ThesisItem Open Access EFFECT OF LAND USE ON SOIL AGGREGATION AND SOIL ORGANIC CARBON FOOTPRINT IN SHIWALIKS OF PUNJAB(Punjab Agricultural University, 2010) Debasish SahaAn understanding of the effect on land use on soil structural stability and soil organic carbon (SOC) is of paramount importance for framing strategies for soil quality management in the present context of increasing atmospheric CO2 concentration. A study was thus conducted in lower Shiwaliks of Punjab (i) to study the impact of different land uses on soil aggregation in relation to soil erodibility and (ii) to study the SOC fractions in different sized aggregates and SOC sequestration under different land uses. Two different approaches of determining aggregate stability were used i.e. by shaking under water and that determined with single simulated rain drop technique (SISRT). The SOC fractions viz. hot water soluble carbon (HWC), particulate organic carbon (POC), labile carbon (LC) were determined. The 1-m profile C stock was determined under different land uses. The concentration of SOC was highest in 0-15 cm layer of grassland soils and lowest in eroded soils but in 15-30 cm layer, it was highest in forest soils. The mean weight diameter (MWD) was highest for surface soils of grasslands (1.13 mm) and lowest in eroded lands (0.19 mm). The SISRT followed the similar trend as MWD. In surface soils, the water-stable macro-aggregates (WSA>2mm) were highest in grassland soils (17.3%) whereas, the micro-aggregates (WSA<0.25mm) were highest (25%) in eroded soils. The SOC in WSA>2mm varied from 7.93 g kg-1 in eroded soils to 17.3 g kg-1 in grassland soils, whereas the SOC in WSA<0.25mm was similar. The SOC decreased with increase in aggregate size and was highest in 1-2 mm aggregates for all the land uses. Among the SOC fractions, the POC was most dominant but LC and HWC showed vulnerability to land use change. The POC was highly correlated (r = 0.83) with wet aggregate stability (WSA>0.25mm) whereas, HWC had good correlation (r = 0.88) with SISRT. The total SOC stock in 1-m profile was highest in forest (83.5 Mg ha-1) and lowest in eroded (55.6 Mg ha-1) soils. The grassland soils had highest C stock (42.5% of total SOC stock) in 0-15 cm soil layer, whereas forest soils stored 73% of the total SOC stock in the subsurface (15-100 cm) layers. The aggregate bulk density was higher than that of whole soils. The water holding capacity of grasslands was highest whereas saturated hydraulic conductivity was similar in forest and grassland soils.
