High variability in leaf gas exchange and related traits were found in 30 genotypes of field grown finger millet. The variability in carbon exchange rate per unit leaf area (PN) can be partly attributed to the differences in the stomatal conductance (gs) and area leaf mass (ALM). The PN was positively correlated with total dry matter (TDM). However, no relationship between PN and seed yield was found. The leaf area showed a positive and significant correlation with total biomass. None of the other gas-exchange traits had significant relationship either with TDM or with seed yield. The ALM showed a strong positive association with PN. However, it was not correlated with either total biomass or seed yield. As a result, the use of ALM as surrogate for PN for identifying high biomass producing genotypes only had a limited value. Hence selection for high PN would result in higher biomass producing types.
Forty two-month-old plants of Dalbergia sissoo and D. latifolia were subjected for 56 d to water deficit induced by withholding water. Drought stress caused a significant reduction in plant height, stem diameter, net photosynthetic rate (PN), transpiration rate (E), and stomatal conductance (gs) in both species, but the reduction was greater in D. sissoo than in D. latifolia. Water use efficiency (PN/E) was adversely affected due to water stress only in D. latifolia, and intrinsic water use efficiency (PN/gs) was increased in both species. There was a slight effect of water stress on variable to maximum fluorescence (Fv/Fm) (quantum yield of photosystem 2) in both species, but the species did not differ significantly in this attribute. and M. Ashraf ... [et al.].
Growth characteristics such as leaf area, fresh and dry mass, and shoot length, and physiological parameters such as photosynthetic and transpiration rates, stomatal conductance, and water use efficiency were reduced by blister blight significantly more in a susceptible tea clone TES-34 than in a tolerant clone SA-6. Also the contents of total sugars, nitrogen, amino acids, proteins, polyphenols, and catechin were reduced more in diseased plant leaves. However, the reduction was more prominent in susceptible than in tolerant clone. Among the different hybrids of tea, Assam hybrid UPASI-3 was highly susceptible to blister blight followed by Cambod UPASI-27 and China UPASI-9. Similarly, tea seedling cv. Caline was highly susceptible to blister blight when compared to tea clone UPASI-3. Susceptibility of tea cultivars to blister blight infection is connected with many physical barriers including leaf area, shoot length, moisture contents, and other physiological and biochemical parameters. and R. Premkumar, P. Ponmurugan, S. Manian.
The effect of elevated carbon dioxide (600±50 cm3 m-3; C600) on growth performance, biomass production, and photosynthesis of Cenchrus ciliaris L. cv. 3108 was studied. This crop responded significantly by plant height, leaf length and width, and biomass production under C600. Leaf area index increased triple fold in the crops grown in the open top chamber with C600. The biomass production in term of fresh and dry biomass accumulation increased by 134.35 (fresh) and 193.34 (dry) % over the control (C360) condition where the crops were grown for 20 d. The rate of photosynthesis and stomatal conductance increased by 24.51 and 46.33 %, respectively, in C600 over C360 plants. In comparison with C360, the rate of transpiration decreased by 6.8 % under C600. Long-term exposure (120 d) to C600 enhanced photosynthetic water use efficiency by 34 %. Also the contents of chlorophylls a and b significantly increased in C600. Thus C. ciliaris grown in C600 throughout the crop season may produce more fodder in terms of green biomass. and R. K. Bhatt, M. J. Baig, H. S. Tiwari.
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.
The combined effects of water stress (WS) and low irradiance (LI) on growth, photosynthesis, osmotic adjustment, and lipid peroxidation were studied in dragon spruce (Picea asperata Mast.) seedlings grown under two water treatments (well watered, 100 % of field capacity, and water stressed, 30 % of field capacity) and two irradiances (HI, 100 % of full sunlight and LI, 15 % of full sunlight). WS reduced growth, chlorophyll (Chl) a and b contents, net photosynthetic rate, transpiration rate, stomatal conductance, and effective quantum yield of photosystem 2 (Y) but increased free proline and malondialdehyde contents. LI increased Chl contents and decreased Y, photochemical quenching (qP), and non-photochemical quenching (qN) under both water treatments. Hence the seedlings in the understory were more sensitive to drought than to LI. and Y. Yang ... [et al.].
A controlled growth chamber experiment was conducted to investigate the short-term water use and photosynthetic responses of 30-d-old carrot seedlings to the combined effects of CO2 concentration (50-1 050 µmol mol-1) and moisture deficits (-5, -30, -55, and -70 kPa). The photosynthetic response data was fitted to a non-rectangular hyperbola model. The estimated parameters were compared for effects of moisture deficit and elevated CO2 concentration (EC). The carboxylation efficiency (α) increased in response to mild moisture stress (-30 kPa) under EC when compared to the unstressed control. However, moderate (-55 kPa) and extreme (-70 kPa) moisture deficits reduced α under EC. Maximum net photosynthetic rate (PNmax) did not differ between mild water deficit and unstressed controls under EC. Moderate and extreme moisture deficits reduced PNmax by nearly 85 % compared to controls. Dark respiration rate (RD) showed no consistent response to moisture deficit. The CO2 compensation concentration (Γ) was 324 µmol mol-1 for -75 kPa and ranged 63-93 µmol mol-1 for other moisture regimes. Interaction between moisture deficit and EC was noticed for PN, ratio of intercellular and ambient CO2 concentration (Ci/Ca), stomatal conductance (gs), and transpiration rate (E). PN was maximum and Ci/Ca was minimum at -30 kPa moisture deficit and at C a of 350 µmol mol-1. The gs and E showed an inverse relationship at all moisture deficit regimes and EC. Water use efficiency (WUE) increased with moisture deficit up to -55 kPa and declined thereafter. EC showed a positive influence towards sustaining PN and increasing WUE only under mild moisture stress, and no beneficial effects of EC were noticed at moderate or extreme moisture deficits. and A. Thiagarajan, R. R. Lada.
The effects of soil flooding on gas exchange and photosystem 2 (PS2) activity were analyzed in leaves of Phragmites australis, Carex cinerascens, and Hemarthria altissima. Pronounced decrease in net photosynthetic rate and stomatal conductance with flooding was found only in C. cinerascens. No significant changes in PS2 activity were observed in all three species which suggests that the photosynthetic apparatus was not damaged. Among the three species, H. altissima is better adapted to flooding than P. australis and C. cinerascens. and M. Li, D. Yang, W. Li.
Species of the Theobroma genus are primarily known by their commercially valuable seeds, especially, T. cacao is one of the most important tropical perennial crops. Beside T. grandiflorum, T. bicolor, and T. angustifolium, T. cacao is the only species of the genus that has been better studied to obtain physiologically relevant information. The main objective of this work was to evaluate the leaf gas exchange in seedlings of seven species of the Theobroma genus, seeking to identify characteristics that could be used in T. cacao breeding programmes. The study was realized under greenhouse conditions using six-month-old seedlings, in which net photosynthetic rate (PN), stomatal conductance (gs), transpiration (E), as well as parameters derived from light curves (PN vs. photosynthetically active radiation) were evaluated. T. cacao, along with T. microcarpum, showed the lowest values of PN, gs, and E, while the highest values were presented by T. speciosum, which showed higher saturation irradiance and lower intrinsic and instantaneous water-use efficiencies, being considered the species less conservative in water use. Therefore, the parameters shown by the different evaluated species could serve to design T. cacao genotypes, through introgression of genes for specific environments such as the cabruca system widespread in southern Bahia, Brazil., A.-A. F. Almeida, F. P. Gomes, R. P. Araujo, R. C. Santos, R. R. Valle., and Obsahuje bibliografii
Gas exchange, water relations, and leaf traits were studied in the tuberous-root producing legumes ahipa (Pachyrhizus ahipa) and yambean (P. erosus) under different environmental conditions. Differences in leaf traits (hairiness, leaf area, areal leaf mass, stomatal density) and paraheliotropism were found between ahipa and yambean. Under sufficient water supply, the increase in air temperature and decrease in air humidity increased stomatal conductance (gs) and net photosynthetic rate (PN) in yambean but reduced them in ahipa. In a drying soil (14 d after irrigation), inter-specific variation in gas exchange was only observed in the early morning, and yambean showed a greater sensitivity to water restriction than ahipa. High gs at low humidity increased PN of P. erosus but resulted in lower water-use efficiency (WUE). However, long-term WUE, estimated by leaf carbon isotope discrimination, showed little variation between species. Daily-irrigated ahipa and yambean grown in the greenhouse did not show significant differences in gas exchange. However, leaf temperature was significantly greater in yambean than in ahipa while a steepper relationship between E and PN and gs was observed in ahipa.