Under natural and greenhouse conditions we found a significant reduction in the physiological and biochemical constituents in leaves of five disease types when compared to healthy ones. The growth characteristics such as height, dry mass, photosynthetic and transpiration rates, stomatal conductance, and water use efficiency were reduced significantly more in susceptible cv. TRI-2024 than in tolerant cv. TRI-2025. Also contents of total sugars, nitrogen, amino acids, proteins, polyphenols, and catechin were reduced in diseased plant leaves. However, the reduction was more prominent in susceptible than tolerant cultivar. Canker size and barker moisture content were larger in the susceptible cultivar than in the tolerant cultivar. and P. Ponmurugan, U. I. Baby, R. Rajkumar.
Seedlings of green gram (Vigna radiata cv. ADT-1 and CO-5) were exposed to daily showers of simulated acidic rain (H2SO4 : HNO3 : HCl, 4 : 2 : 1, v/v) for 10 d. The effects were analysed after 5 and 10 showers, respectively. Rain of pH 2.5 inhibited seedling growth and biomass accumulation, though in other acidic levels the effects were mostly inconsistent. Both cultivars had high degree of surface wettability indicated by high leaf surface contact angles and water-holding capacity. Treated leaves were thinner with smaller mesophyll cells. Stomatal index and trichome density were lower in contrast to epidermal cell density and stomatal frequency which increased with increasing acidity. Decreases in chlorophyll (Chl), carotenoid (Car), and starch contents in cv. ADT-1 at pH 2.5 were observed after 5 showers, while in cv. CO-5 decreases were noted only after 10 showers. In contrast to total sugar levels, the protein content of cv. CO-5 was augmented significantly after simulated acidic rain (SAR) treatment. and G. Kumaravelu, M. P. Ramanujam.
Changes in growth parameters and 14CO2 and [U-14C]-sucrose incorporation into the primary metabolic pools and essential oil were investigated in leaves and stems of M. spicata treated with etherel and gibberellic acid (GA). Compared to the control, GA and etherel treatments induced significant phenotypic changes and a decrease in chlorophyll content, CO2 exchange rate, and stomatal conductance. Treatment with etherel led to increased total incorporation of 14CO2 into the leaves wheras total incorporation from 14C sucrose was decreased. When 14CO2 was fed, the incorporation into the ethanol soluble fraction, sugars, organic acids, and essential oil was significantly higher in etherel treated leaves than in the control. However, [U-14C]-sucrose feeding led to decreased label incorporation in the ethanol-soluble fraction, sugars, organic acids, and essential oils compared to the control. When 14CO2 was fed to GA treated leaves, label incorporation in ethanol-insoluble fraction, sugars, and oils was significantly higher than in the control. In contrast, when [U-14C]-sucrose was fed the incorporation in the ethanol soluble fraction, sugars, organic acids, and oil was significantly lower than in the control. Hence the hormone treatment induces a differential utilization of precursors for oil biosynthesis and accumulation and differences in partitioning of label between leaf and stem. Etherel and GA influence the partitioning of primary photosynthetic metabolites and thus modify plant growth and essential oil accumulation. and Preety Singh ... [et al.].
Changes in growth parameters, carbon assimilation efficiency, and utilization of 14CO2 assimilate into alkaloids in plant parts were investigated at whole plant level by treatment of Catharanthus roseus with gibberellic acid (GA). Application of GA (1 000 g m-3) resulted in changes in leaf morphology, increase in stem elongation, leaf and internode length, plant height, and decrease in biomass content. Phenotypic changes were accompanied by decrease in contents of chlorophylls and in photosynthetic capacity. GA application resulted in higher % of total alkaloids accumulated in leaf, stem, and root. GA treatment produced negative phenotypic response in total biomass production but positive response in content of total alkaloids in leaf, stem, and roots. 14C assimilate partitioning revealed that 14C distribution in leaf, stem, and root of treated plants was higher than in untreated and variations were observed in contents of metabolites as sugars, amino acids, and organic acids. Capacity to utilize current fixed 14C derived assimilates for alkaloid production was high in leaves but low in roots of treated plants despite higher content of 14C metabolites such as sugars, amino acids, and organic acids. In spite of higher availability of metabolites, their utilization into alkaloid production is low in GA-treated roots. and N. K. Srivastava, A. K. Srivastava.
Fluorescence images of leaves of sugar beet plants (Beta vulgaris L. cv. Patricia) grown on an experimental field with different fertilisation doses of nitrogen [0, 3, 6, 9, 12, 15 g(N) m-2] were taken, applying a new multicolour flash-lamp fluorescence imaging system (FL-FIS). Fluorescence was excited by the UV-range (280-400 nm, λmax = 340 nm) of a pulsed Xenon lamp. The images were acquired successively in the four fluorescence bands of leaves near 440, 520, 690, and 740 nm (F440, F520, F690, F740) by means of a CCD-camera. Parallel measurements were performed to characterise the physiological state of the leaves (nitrogen content, invert-sugars, chlorophylls and carotenoids as well as chlorophyll fluorescence induction kinetics and beet yield). The fluorescence images indicated a differential local patchiness across the leaf blade for the four fluorescence bands. The blue (F440) and green fluorescence (F520) were high in the leaf veins, whereas the red (F690) and far-red (F740) chlorophyll (Chl) fluorescences were more pronounced in the intercostal leaf areas. Sugar beet plants with high N supply could be distinguished from beet plants with low N supply by lower values of F440/F690 and F440/F740. Both the blue-green fluorescence and the Chl fluorescence rose at a higher N application. This increase was more pronounced for the Chl fluorescence than for the blue-green one. The results demonstrate that fluorescence ratio imaging of leaves can be applied for a non-destructive monitoring of differences in nitrogen supply. The FL-FIS is a valuable diagnostic tool for screening site-specific differences in N-availability which is required for precision farming. and G. Langsdorf ... [et al.].
Incorporation of photosynthetically fixed 14C was studied at different time intervals of 12, 24, and 36 h in various plant parts-leaf 1 to 4 from apex, roots, and rhizome-into primary metabolites-sugars, amino acids, and organic acids, and secondary metabolites-essential oil and curcumin-in turmeric. The youngest leaves were most active in fixing 14C at 24 h. Fixation capacity into primary metabolites decreased with leaf position and time. The primary metabolite levels in leaves were maximal in sugars and organic acids and lowest in amino acids. Roots as well as rhizome received maximum photoassimilate from leaves at 24 h; this declined with time. The maximum metabolite concentrations in the roots and rhizome were high in sugars and organic acids and least in amino acids. 14C incorporation into oil in leaf and into curcumin in rhizome was maximal at 24 h and declined with time. These studies highlight importance of time-dependent translocation of 14C-primary metabolites from leaves to roots and rhizome and their subsequent biosynthesis into secondary metabolite, curcumin, in rhizome. This might be one of factors regulating the secondary metabolite accumulation and rhizome development. and Deeksha Dixit, N. K. Srivastava.
Changes in leaf growth, photosynthetic efficiency, and incorporation pattern of photosynthetically fixed 14CO2 in leaves 1 and 2 from plant apex, in roots, and rhizome induced in Curcuma by growing in a solution culture at Fe concentration of 0 and 5.6 g m-3 were studied. 14C was incorporated into primary metabolites (sugars, amino acids, and organic acids) and secondary metabolites (essential oil and curcumin). Fe deficiency resulted in a decrease in leaf area, its fresh and dry mass, chlorophyll (Chl) content, and CO2 exchange rate at all leaf positions. The rate of 14CO2 fixation declined with leaf position, maximum being in the youngest leaf. Fe deficiency resulted in higher accumulation of sugars, amino acids, and organic acids in leaves at both positions. This is due to poor translocation of metabolites. Roots and rhizomes of Fe-deficient plants had lower concentrations of total photosynthate, sugars, and amino acids whereas organic acid concentration was higher in rhizomes. 14CO2 incorporation in essential oil was lower in the youngest leaf, as well as incorporation in curcumin content in rhizome. Fe deficiency influenced leaf area, its fresh and dry masses, CO2 exchange rate, and oil and curcumin accumulation by affecting translocation of assimilated photosynthates. and Deeksha Dixit, N. K. Srivastava.
Wheat (T. durum cvs. HD 4502 and B 449, T. aestivum cvs. Kalyansona and Kundan) and sunflower (Helianthus annuus L. cv. Morden) were grown under atmospheric (360±10 cm3 m-3, AC) and elevated CO2 (650±50 cm3 m-3, EC) concentration in open top chambers for entire period of growth and development till maturity. Leaf net photosynthetic rate (PN) of EC-grown plants of wheat measured at EC was significantly decreased in comparison with AC-plants of wheat measured at EC. Sunflower, however, showed no significant depression in PN in EC-plants. There was a decrease in ribulose-1,5-bisphosphate carboxylase (RuBPC) activity, its activation state and amount in EC-plants of wheat, whereas no significant decrease was observed in sunflower. The above different acclimation to EC in wheat and sunflower was related with saccharide constituents accumulated in the leaves. Under EC, sunflower accumulated in the leaves more starch, whereas wheat accumulated more sugars. and M. C. Ghildiyal, S. Rafique, P. Sharma-Natu.
Wheat (Triticum aestivum L. cv. HD 2329 and DL 1266-5) and sunflower (Helianthus annuus L. cv. MSFH 17 and MRSF 1754) plants were grown in field under atmospheric (360±10 cm3 m-3, AC) and elevated (650±50 cm3 m-3, EC) CO2 concentrations in open top chambers for entire period of growth and development till maturity. Net photosynthetic rate (P N) of wheat cvs. when compared at the same internal CO2 concentration (Ci), by generating PN/Ci curves, showed lower PN in EC plants than in AC ones. EC-grown wheat cultivars also showed a lesser response to irradiance than AC plants. In sunflower cultivars, PN/Ci curves and irradiance response curves were not significantly different in AC and EC plants. CO2 and irradiance responses of photosynthesis, therefore, further revealed a down-regulation of P N in wheat but not so in sunflower under long-term CO2 enrichment. Wheat cvs. accumulated in leaves mostly sugars, whereas sunflower accumulated mainly starch. This further strengthened the view that accumulation of excess assimilates in the leaves under EC as starch is not inhibitory to PN. and V. Pandurangam ... [et al.].
14CO2 uptake in leaves of wheat plants (Triticum aestivum L.) fertilized by urea or Ca(NO3)2 (25 mol m-3) was investigated. The Warburg effect (inhibition of 14CO2 uptake by oxygen) under 0.03 vol. % CO2 concentration was observed only in non-fertilized plants. Under 0.03 vol. % CO2, the Warburg antieffect (stimulation of 14CO2 uptake by oxygen) was detected only in plants fertilized by Ca(NO3)2. Under saturating CO2 concentration (0.30 vol. %), the Warburg antieffect was observed in all variants. Under limitation of ribulose-1,5-bisphosphate carboxylase/oxygenase activity (0.30 vol. % CO2 + 1 vol. % O2), the rate of synthesis of glycollate metabolism products decreased in control and urea-fertilized plants but was enhanced in nitrate-fed plants. Hence, there was an activation of glycollate formation via transketolase reaction in fertilized plants, and the products of nitrate reduction function were oxidants in nitrate-fertilized plants whereas the superoxide radical played this role in urea-fertilized plants. and V. Chikov, G. Bakirova.