, T., Garabet, S., Pala, M. 1998. Water-use efficiency and transpiration efficiency of wheat under rain-fed conditions and supplemental irrigation in a Mediterranean-type environment. Plant Soil 201 :295
Investigations of the water regime of the plant species
L. (Scrophulariaceae) were conducted to examine ecological characteristics and the physiological status of the species from different geological substrates of its habitats (from the serpentine, andesite, dacite, limestone) in the flora of Serbia.
Authors:M. Mori, M. Inagaki, T. Inoue, and M. Nachit
Zhang, H., Oweis, T., Garabet, S., Pala, M. 1998. Water-use efficiency and transpiration efficiency of wheat under rain-fed conditions and supplemental irrigation in a Mediterranean-type environment. Plant Soil 201 :295
Changes in the microclimate and transpiration of reedbeds on the shores of Lake Balaton, some still standing in water and some from which the water has receded, were examined in Keszthely Bay during the 2003 vegetation cycle, after canopy closure. Microclimate data were recorded using combined sensors connected to a data-collector. Ten-minute means calculated from data recorded every two seconds were used as the basis of comparison. Transpiration was quantified using the shoot mass loss method. The leaf area index of reeds growing on dry areas was greater than that of plants rooted in the lake. This difference was moderate at first, but increased greatly during the vegetative phase, and could be attributed primarily to differences in plant density and leaf size, and to the effect of waves. Among the components of the microclimate, the humiditywithin the stand was 8-20% greater for plants growing in water, irrespective of the weather and the development stage. The daily mean air temperature was lower in the dry stand, and exhibited considerable daily fluctuations. The mean daily sum of transpiration, averaged over three sample days, was 16.5% lower in the dry stand. The plot of daily changes in transpiration exhibited two peaks for the dry stand and one for the wet stand.
The stress reaction of maize plants was evaluated in relation to drought stress intensity and to growth stages by assessing the transpiration intensity and the expression of two dehydrin genes, DHN1 and DHN2. The maize plants were grown under four different watering conditions: well-watered (control), mild stress, moderate stress and high stress. The sap flow values were taken as an indicator of plant stress reactions at the transpiration level. A significant correlation between the average diurnal values of sap flow and the volumetric soil moisture appeared only for the moderate stress condition (R = 0.528) and for the high stress condition (R = 0.395). Significant increases in the expression of DHN1 and DHN2 (DHN1 = 105-fold and DHN2 = 103-fold) were observed primarily for the high stress condition compared to the control. Differences in the stress reactions at the DHN1 gene expression level were detected for all the experimental drought stress conditions. A relatively close relationship between the levels of expression of both genes and the values of the sap flow was observed during the initial stage of the stress (R = –0.895; R = –0.893). The severity of water stress and transpiration intensity significantly affected certain biometric and yield parameters of maize. Higher DHN genes expression at the ripening stage was related to lower grain and dry biomass yield. The results indicated that DHN gene expression assessment in maize and evaluation of the changes in transpiration expressed by the sap flow could be considered appropriate indicators of stress intensity while the DHN gene expression assessment appeared to be more sensitive than evaluation of the changes in transpiration, mainly in the initial phases of stress response.
Transpiration method was used to measure the equilibrium water vapor pressures of the dehydration of the respective hydrates,
such as oxalates, sulfates,chlorides and acetate, and the enthalpies of dehydrations (ΔHTr0) of these hydrates were obtained. The heats of dehydrations (ΔHDSC0) were also determined by TG-DSC method. From the comparison with ΔHTr0 of ΔHDSC0, the relation of ΔHDSC0/ΔHTr0=R (=dehydration molar number determined by TG-DSC peak/stoichiometric dehydration molar number) was yielded. From these results,
the following relations were found: ΔHDSC0(corrected)=ΔHDSC0/R=ΔHTr0
Authors:Abeer H. Ali, Usama Radwan, Soad El-Zayat, and Magdi A. El-Sayed
transferring into field station under normal climatic conditions.
Measurement of photosynthetic parameters
Measurements of photosynthesis (Pn) rate, transpiration (Tr) rate, leaf intercellular CO 2 concentration, and
Drought adaptation of wheat is one of the most significant and complex subjects in the rain-fed agricultural regions of West Asia. Interaction between root water-uptake and the remaining soil moisture is a key factor for drought adaptation. Under controlled conditions, root development was compared among four wheat genotypes under water deficit stress in relation to water-uptake. In addition, the effects of soil water deficit on the production of biomass and grain were examined using drought-adaptive varieties from different sources.Genotypic differences in root development were significant by the time of heading under well-irrigated conditions but were decreased under water-stressed conditions. After heading, water deficit stress also decreased grain yield through a reduction in grain number. Genotypic variations in transpiration efficiency and harvest index, two components of water-use efficiency, were significant and transpiration efficiency was negatively associated with root weight and water-uptake. The effect of harvest index was three-times greater than that of transpiration efficiency. Two wheat genotypes, SYN-10 and Drysdale derived from different sources, had high grain weights in contrast to reduced root development and low water-uptake under water deficit stress. Their differences in genetic mechanism remain uncertain.Transpiration efficiency and harvest index are critical factors for producing greater grain yield under water deficit stress. These components are closely related and highly dependent on wheat genotype. Harvest index was more determinant of grain yield than transpiration efficiency. The drought-adaptive wheat genotypes achieved water-savings through reduced root weight and reduced water-uptake and compensated for these through higher transpiration efficiency and higher harvest index.
Authors:T. Zsom, W. B. Herppich, Cs. Balla, A. Fekete, J. Felföldi, and M. Linke
Sweet pepper is susceptible to relatively fast quality changes and its quality is influenced strongly by water or mass losses
mainly due to transpiration processes during post-harvest. The aim of this study was the investigation of different storage
conditions' effect on quality maintenance of pepper using surface thermal imaging, measurement of overall static stiffness
and low-mass impact stiffness as non-destructive methods. Post-harvest keeping quality of pepper samples increased and unfavourable
quality degradation was prevented under low, non-chilling temperatures together with the use of LDPE-packaging film resulted
in high quality and fresh appearance after more than two weeks long storage period.