Relationship between wheat yield and foliage temperature: theory and its application to infrared measurements

A theoretical basis is presented for the relationship between crop yield and one time-of-day measurements of the foliage-ambient temperature differential (T_f — T_a). The theory was used to analyse two contrasting relationships between wheat yield and T_f — T_a. The relationships resulted from a range of irrigation treatments and two times of sowing imposed on 26 plots. This caused yields to vary from 8.3 to 1.7 t ha^?1 when the crop was sown in June and from 5.5 to 2.2 t ha^?1 when sown in August. To explain these variations T_f — T_a and associated micrometeorological data were collected around solar noon during the period from jointing to maturity. From these data transpiration and the associated aerodynamic and canopy stomatal resistances to water vapour transport were predicted. The associated canopy conductances for diffusion of CO₂ were derived and used to predict the corresponding CO₂ assimilation rates.The predicted transpiration and CO₂ assimilation rates were closely related to yield within each year but not between years. However if the rates were normalised for the shorter growing season of the late sown crop the yields from the 26 plots formed a common relationship. The transpiration vs. yield relationship was further improved by normalising for differences in foliage vapour pressure deficit. The good agreement between field data and theory was probably due to the dominating effect of stomatal control on both T_f — T_a and CO₂ assimilation rate. If CO₂ assimilation rate is strongly influenced by factors other than soil water stress then the theory may not hold and a different relationship may exist. It was concluded that infrared thermometry is a useful technique for studying yield variations in agronomic experiments where these variations are due to stomatal control.     

Copper Complexing Capacity of Throughfall and its Environmental Effect

Copper complexing capacity (CuCC) and conditional stability constants (K′) of the complexes were analyzed for throughfall collected in Japanese cypress (Chamaecyparis obtusa), Japanese cedar (Cryptomeria japonica), Japanese red pine (Pinus densiflora), and bamboo-leafed oak (Quercus myrsinaefolia) groves (soil: light-colored Andosol) located in a suburban area of Japan (Tsukuba, Ibaraki). The method was based on the titration of throughfall samples with standard Cu²⁺ solution using a Cu²⁺-selective electrode, followed by data analysis using the van den Berg-Ruzic plot (1:1-type complexes were assumed). CuCCs (μM) obtained were in the order: C. obtusa (7.1± 5.1) ≤ C. japonica (9.6± 5.6) < P. densiflora (15.9± 16.4) < Q. myrsinaefolia (29.3± 23.9). In addition, ratios of CuCC/DOC (μmol mg^?1 C) were in the order: C. obtusa (0.42± 0.26) ? C. japonica (0.42± 0.22) ? P. densiflora (0.55± 0.38) ? Q. myrsinaefolia (2.0± 1.3), and the ratios in the throughfall of Q. myrsinaefolia were about 4 times higher than those in the throughfall of other tree species. On the other hand, log K′ was almost the same for all tree species (about 5.5). CuCC and also CuCC/DOC increased in spring and autumn, and decreased in summer and winter, indicating that organic matter with metal complexing capacity, released from trees, changed seasonally not only in quantity but also in quality. Since throughfall accelerated the leaching of metals from grove soil and artificial material (e.g. alloy) placed in the groves, it may be involved in the behavior of metals in the plant-soil ecosystem.     

Proteolytic activities of suparen and rennilase on buffalo, cow, and goat whole casein and beta-casein.

The proteolytic specificity and activity of Mucor miehei protease (Rennilase) and Endothia parasitica protease (Suparen) on buffalo, cow, and goat whole casein and beta-casein (CN) were studied by analyzing the degradation products. The results suggest that Rennilase hydrolyzes casein of the three species in a manner similar to that of chymosin, resulting in the formation of alpha(s1)-I and beta-I, -II, -III as initial degradation fragments of alpha(s1)- and beta-CN. alpha(s1)-I was also the initial breakdown product of alpha(s1)-CN by Suparen. Contrary to Rennilase, Suparen showed a higher affinity toward beta-CN and hydrolyzes beta-CN, giving rise to degradation products characterized by mobility lower than that of beta-CN. Increasing NaCl concentration (>3%) reduced the proteolysis of beta-CN of the three species by Rennilase but not by Suparen. The hydrolysis of alpha(s1)-CN and alpha(s1)-I by the two enzymes was enhanced in the presence of NaCl.     

Transpiration from coppiced poplar and willow measured using sap-flow methods

Transpiration rates from poplar (Beaupré, Populus trichocarpa×deltoides) and willow (Germany, Salix burjatica) clones, grown as short-rotation coppice (three-year-old stems on four-year-old stools) at a site in south-west England, were measured through the summer of 1995. Area-averaged transpiration was estimated by scaling sap-flow rates measured in individual stems to a stand area basis using measurements of leaf area and stem diameter distribution. Sap flow in poplar was measured using the stem heat balance, heat pulse velocity and deuterium tracing techniques; in willow only the stem heat balance method was used. In June and early July the mean daily transpiration from the poplar was 6±0.5 mm day⁻¹, stomatal conductances averaged 0.33 mol m⁻² s⁻¹ for leaves in the upper layer of the canopy and daily latent heat flux often exceeded the daily net radiation flux. Similarly high transpiration was estimated for the willow. The transpiration rates were higher than any reported rates from agricultural or tree crops grown in the UK and arose because of high aerodynamic and stomatal conductances. The high stomatal conductances were maintained even when atmospheric humidity deficits and soil water deficits were large. Much lower rates (1±1 mm day⁻¹) from both clones were recorded in August at the end of a drought period.These results suggest that extensive plantation of poplar or willow short-rotation coppice will result in reduced drainage to stream flow and aquifer recharge.     

Responses of transpiration and canopy conductance to partial defoliation of Eucalyptus globulus trees

Partial defoliation has been shown to affect the water relations and transpiration (gas exchange) of plants. Over one growing season, the water relations in response to partial (∼45%) defoliation were examined in four-year-old Eucalyptus globulus trees in southern Australia. Daily maximum transpiration rates (E_max), maximum canopy conductance (GCmax), and diurnal patterns of tree water-use were measured over a period of 215 days using the heat-pulse technique in adjacent control (non-defoliated) and defoliated trees. Sap-flux measurements were used to estimate canopy conductance and soil-to-leaf hydraulic conductance (K_P); leaf water potential (Ψ) and climate data were also collected. Following the removal of the upper canopy layer, defoliated trees exhibited compensatory responses in transpiration rate and canopy conductance of the remaining foliage. Defoliated E. globulus had similar predawn but higher midday Ψ_l, transpiration rates (E), canopy conductance (G_C) and K_P compared to the non-defoliated controls, possibly in response to increased water supply per unit leaf area demonstrated by higher midday Ψ_l. Higher E in defoliated E. globulus trees was the result of higher G_C in the morning and early afternoon. This paper also incorporates the cumulative effect of defoliation, in a phenomenological model of maximum canopy conductance of E. globulus. These results contribute to a mechanistic understanding of plant responses to defoliation, in particular the often observed up-regulation of photosynthesis that also occurs in response to defoliation.     

Cadmium in Fagus sylvatica L. trees and seedlings: Leaching,uptake and interconnection with transpiration

Most of the airborne Cd-polluted particles which eventually precipitate in forest regions remain on the surface of the tree leaves and do not penetrate into the plants' live tissues. Such pollutions can be removed from the leaves by cation exchange or can be washed off with water of low pH. Acid rains and acid soils have contributed very much to the solubilization of Cd and to its transformation into an available ionic form which is later absorbed by tree roots. ^115mCd uptake by young beech trees (Fagus sylvatica L.) seems to be positively correlated with the concentrations of the applied solutions as well as with the duration of the exposure. Low environmental pH increases the rate of ^115mCd uptake. High or low transpiration had no apparent effect on root absorption of Cd, but exposure of beech trees to a Cd(NO₃)₂ solution reduced their rates of transpiration after very few days of treatment.     

Photosynthetic Response of Maize Plants Against Cadmium and Paraquat Impact

The effects of cadmium (Cd) and/or paraquat (PQ) toxicity on photosynthesis in maize leaves were examined by measurement of gas exchange and chlorophyll content in hydroponically cultured plants. It was found that growth rate was distinctly influenced only by 100 µM Cd treatment. Chlorophyll a and chlorophyll b decreased along with the increase of Cd concentration, while PQ spraying, alone and combined with Cd, increased chlorophyll a content on the third and seventh experimental days. Generally, carotenoid content increased in response to Cd and PQ and reached the highest levels at 100 µM Cd. Rate of photosynthesis in maize decreased after Cd treatment. CO₂ assimilation was approximately 60% reduced at 50 µM Cd and 70% reduced in the presence of 100 µM Cd. PQ toxicity was partly overcome after the third day of exposure. Transpiration and stomatal conductance in maize leaves decreased on the third day along with Cd concentration and PQ spraying, except for the 25-µM Cd-treated plants. On the tenth day, the 25-µM Cd-treated plants and those from PQ-treated variants showed an increase of transpiration and stomatal conductance. Maize exhibited an ability to accumulate Cd in high quantities, especially in the roots—over 4,500 mg Cd/kg dry weight.     

Calcium concentration in leaf litter alters the community composition of soil invertebrates in warm-temperate forests

Many studies have shown the effects of aboveground plant species on soil organisms due to differences in litter quality. However, the calcium concentration in soil has received less attention as a controlling factor of soil invertebrate communities, even though it is an essential element for many animals, especially crustaceans. Litter of Japanese cedar (Cryptomeria japonica) plantations, which account for 19% of the forested area in Japan, has a higher calcium concentration compared to other taxa such as broad-leaved trees. We predicted that C. japonica plantations affect soil invertebrates by altering calcium availability. We compared soil properties including exchangeable calcium concentration and soil invertebrate communities between C. japonica plantations and natural broad-leaved forests. Exchangeable calcium was significantly higher in soil from cedar plantations than in that from broad-leaved forests. The invertebrate community composition differed between the two forest types and was best explained by the exchangeable calcium concentration. In particular, two major taxa of soil crustaceans (Talitridae and Ligidium japonicum) were found only in cedar plantations. Our results suggest that calcium concentrations in soil are altered in C. japonica plantations and that this affects soil invertebrate communities.     

Water use by tamarillos (Cyphomandra betacea) within a sheltered orchard environment

The transpiration of Tamarillos (Cyphomandra betacea (Cav.), Sendt.) grown in a sheltered orchard was measured periodically through a season. A series of excision experiments provided daily water uptake data which agreed closely with rates calculated on the basis of equilibrium transpiration and projected canopy area. Comparative porometer and leaf water potential measurements indicated that the excised trees functioned normally over the measurement periods. Shelter apparently reduced the influence of advection on evaporation with the result that transpiration was strongly dependent on net radiation.     

Genetic diversity in Japanese aromatic rice (Oryza sativa L.) as revealed by nuclear and organelle DNA markers

Aromatic rice (Oryza sativa L.) cultivated in Japan is regionally differentiated by geographical distribution and characteristics. We aimed to characterize the lineage of Japanese aromatic rice using DNA markers. Based on analyses with nuclear SSR markers, we found that Japanese aromatic rice cultivars belong, with one exception, to japonica but showed some differences from authentic japonica and were divided into two clades that were distributed in western and eastern Japan, respectively. Further analyses with organelle markers showed that most of the cultivars in eastern Japan had cytoplasm characterized by tropical japonica, whereas most of those in western Japan had cytoplasm characterized by temperate japonica. We postulate that the ancestor of the cultivars in eastern Japan differs from those of the cultivars in western Japan, and that the two groups may have been separately introduced from Taiwan into Japan. The cytoplasm of aromatic rice cultivars in western Japan may have originated from tropical japonica and been substituted into the cytoplasm of temperate japonica through hybridization between tropical japonica as a male parent and temperate japonica as a female parent.     

Rice Bran Addition to Leaf Compost Can Reduce Radiocesium Concentration and Its Uptake by Crops After the Fukushima Daiichi Nuclear Power Plant Accident

Abstract

Leaf composting is an essential technique in organic farming; it improves the physicochemical properties of soil such as texture, structure, water-holding capacity, and nutrient content. However, the use of leaf compost is prohibited in the Fukushima and Ibaraki prefectures because large areas of the Fukushima and Ibaraki forests were contaminated by radiocesium (¹³⁴Cs and ¹³⁷Cs) after the Fukushima Daiichi nuclear power plant (FDNPP) accident. We examined the changes in radio Cs concentration and other physicochemical properties in leaf compost made from Ibaraki and Fukushima forest leaves. At the beginning of the composting process, rice bran-treated compost showed 25%–32% lower radio Cs concentration than the leaf-only compost; however, 2?years after composting, the difference in concentration between these treatments had increased to 35%–63%. Moreover, the incorporation of rice bran significantly increased the compost temperature, moisture, electrical conductivity, bulk density, and total nitrogen during the composting process. Plant uptake of radio Cs was significantly lower in rice bran-treated compost than the leaf-only compost at each level of application; furthermore, the levels of soil radio Cs showed a similar trend. Potassium application combined with leaf compost resulted in a significant reduction of radio Cs plant uptake. Our data revealed that adding rice bran to leaves positively affects radio Cs reduction in leaf compost and also reduces its uptake by plants. Our findings may improve the management of leaf composting after the FDNPP accident.     

Contribution of dissolved organic nitrogen deposition to nitrogen saturation in a forested mountainous watershed in Tsukui, Central Japan

Nitrogen (N) budget was estimated with dissolved inorganic N (DIN) and dissolved organic N (DON) in a forested mountainous watershed in Tsukui, Kanagawa Prefecture, about 50 km west of Tokyo in Central Japan. The forest vegetation in the watershed was dominant by Konara oak (Quercus serrata) and Korean hornbeam (Carpinus tschonoskii), and Japanese cedar (Cryptomeria japonica). Nitrate (NO₃ ^?) concentration in the watershed streamwater was averagely high (98.0 ±± 19 (±± SD, n = 36) μmol L^?1) during 2001–2003. There was no seasonal and annual changes in the stream NO^? ₃ concentration even though the highest N uptake rate presumably occurred during the spring of plant growing season, a fact indicating that N availability was in excess of biotic demands. The DON deposition rates (DON input rates) in open area and forest area were estimated as one of the main N sources, accounting for about 32% of total dissolved N (TDN). It was estimated that a part of the DON input rate contributed to the excessive stream NO^? ₃ output rate under the condition of the rapid mineralization and nitrification rates, which annual DON deposition rates were positively correlated with the stream NO₃ ^? output rates. The DON retention rate in the DON budget had a potential capacity, which contributed to the excessive stream NO^? ₃ output rate without other N contributions (e.g. forest floor N or soil N).     

A model to simulate response of plant stomata to environmental conditions

In order to simulate plant transpiration under different field climatic conditions we have developed and verified a semi-empirical model for predicting the stomatal response to solar global radiation, leaf temperature, vapour pressure difference between the leaf and ambient air, ambient air CO₂ concentration and soil water potential. The transpiration and the stomatal relative conductance of a Nicotania Tabaccum var “samsun” plant leaves were measured in a laboratory apparatus and compared to those predicted by the model: good agreement was obtained between them for the different investigated cases. The model was incorporated in a numerical greenhouse microclimate model and its effects on the canopy microclimate are discussed here.     

Use of a greenhouse as an open chamber for canopy gas exchange measurements: Methodology and validation

Measurements of whole-canopy gas exchange - of CO₂ and H₂O - are important for agricultural and ecological reasons. The objective of this study was to investigate the use of a full-size greenhouse as an open-chamber system for measuring canopy-scale gas exchange. Measurements were validated by comparison with gas exchange scaled up from leaf- and plant-level measurements. Leaf-level measurements used a conventional hand-held cuvette gas exchange system at many points in the greenhouse. The experiments were done in a greenhouse with an area of (15 × 24) m² in which a pepper crop was grown. Within the canopy photosynthetic activity and transpiration changed with height, as expected. In addition, it was shown both theoretically and experimentally that in the absence of air mixing within the chamber, gradients of CO₂ and H₂O developed along the airflow direction. Theoretical estimates of the gradients were in good agreement with measured values. In spite of the gradients, canopy photosynthesis and transpiration could be estimated relatively accurately. For instance, the values of canopy photosynthesis and transpiration, during the course of the day, as measured with the open-chamber approach, were in good agreement with mean values obtained from measurements on individual leaves. However, transpiration values obtained both from open-chamber measurements and from individual leaves were generally a little lower than those obtained with lysimeters.     

Plant water relations in lychee: Effects of solar radiation interception on leaf conductance and leaf water potential

The effect of radiation interception on leaf conductance and leaf water potential in six-years old lychee trees (Litchi chinensis Sonn. cv. Bengal) was investigated during the dry season in subtropical Queensland, Australia. A high degree of exposure of leaves to direct radiation raised leaf-air water vapour concentration gradient (Δw) and resulted in lower leaf conductance and leaf water potential. Interior leaves of the south side of trees were less sensitive to atmospheric and radiation effects and are the best indicator of drought stress in lychee. Completely random or stratified sampling is necessary to estimate a true mean value for calculation of canopy transpiration or photosynthesis.     

Annual Variations of Needle Surface Characteristics of Pinus Sylvestris Growing Near the Emission Source

In present study, pollutant effects on needle surface characteristics of Pinus sylvestris in the area affected by a nitrogen fertilizer plant have been investigated over 1994–1997 year period. Near the factory, sites with 15–25-year-old trees on a 0.5–22 km interval were chosen. Mean monthly concentrations of NO₂ and NH₃ varied across the transect in the range of 1.8–8.8 µg m^?3 and 1.8 – 69.3 µg m^?3, respectively. NH₃ concentrations exceeded the critical level (>23 µg m^?3) only in the 0.5 km vicinity. Assessment of needle surface wettability by measuring contact angles (CA) of water droplets and surface quality by measuring stomatal area covered by structural wax (SW) revealed significant (p<0.05) needle age, site, and year of sampling related differences. Comparison of SW between sites showed reliably (p<0.05) higher surface wax erosion on one-year-old needles sampled in the area, where ammonia concentration exceeds critical level. Significant correlations between site SW on one-year-old needles and distance from the pollution source, NO₂ and NH₃ concentrations were detected (r = 0.539; r = ? 0.495; r = ? 0.426; p<0.001, respectively). Correlations between CA and factors mentioned were lower.     

Effects of air pollution on the chemistry of surface waxes of scots pine

Surface waxes from Scots pine (Pinus sylvestris) trees from the same provenance, but growing at a polluted and an unpolluted site, were sampled for each year class of needles at least twice during the year.There was no change in the amount of wax per unit area over the lifetime of the needles, but less wax was obtained from trees at the polluted site.Quantitative thin-layer chromatography of the wax gave several components which decreased in amount with time. They were identified as long-chain alcohols and ketones, and comprised only a small proportion of the total wax. The rate of change was greater in polluted air than in clean air, and there was a strong correlation with measured contact angles for water droplets. The degradation in structure observed by scanning electron microscopy may be associated with particular chemical components of the surface wax.     

Einfluß exogener und endogener Faktoren auf den Calciumgehalt von Paprika- und Bohnenfrüchten

Effect of external and internal factors on the calcium content of paprika and bean fruits In water culture experiments with paprika and bean plants the effect of Ca supply, transpiration and growth rate on the Ca content of the fruits has been studied. A 10-fold increase in Ca supply only slightly increased the Ca content. The Ca content of the paprika fruits was increased considerably at high transpiration rates of either the whole shoot or the single fruit. High transpiration also increased the Mg content but had no effect on the K content. In bean high transpiration rates only increased the Ca content in the early stages of fruit development. The ratio of Ca translocation versus water loss by transpiration sharply declined during fruit growth in both species. In paprika the highest ratio (μg Ca/ml) in the fruits corresponded with the ratio in the leaves. In bean fruits, however, this ratio distinctly exceeded that of fully developed leaves. At high transpiration rates of the shoot 20% of the Ca (⁴⁵Ca) injected into the fruit were translocated out of the fruit. At low transpiration rates of the shoot the corresponding value was below 1%. Most of all the growth rate of the fruits affected the Ca content. With increasing growth rate the Ca transport into the fruits was hardly altered which in turn led to a sharp decrease of the Ca content per unit dry weight. The results support the idea of the Ca transport into the fruit via the xylem. This Ca transport — i.e. also the Ca content of the fruit — is regulated and is also to be influenced by direct or indirect alterations of the water transport in the xylem.     

Sensitivity analysis of the SWAP (Soil-Water-Atmosphere-Plant) model under different nitrogen applications and root distributions in saline soils

Sensitivity analysis is important for determining the parameters in the model calibration process. In our study, a variance-based global sensitivity analysis (extended Fourier amplitude sensitivity test, EFAST) was applied to an agro-hydrological model (the SWAP (Soil-Water-Atmosphere-Plant model) model). The sensitivities of 20 parameters belonging to 4 categories (soil hydraulics, solute transport, root water uptake, and environmental stresses) for the simulated accumulated transpiration, dry matter (DM), and yield of sunflowers were analyzed under three nitrogen application rates (N1, N2, and N3), four salinity levels (S1, S2, S3, and S4), and three root distributions (R1, R2, and R3). The results indicated that for predominantly loamy soils, the high-impact parameters for accumulated transpiration, DM, and yield were the soil hydraulic parameters (α and n), critical stress index for compensatory root water uptake (ω_c), the salt level at which salt stress starts (Pi), the decline of root water uptake above Pi (SSF), residual water content (θ_r), saturated water content (θ_s), and relative uptake of solutes by roots (TSCF). We also found that nitrogen application did not change the order of the parameter impacts on accumulated transpiration, DM, and yield. However, TSCF replaced α as the highest-impact parameter for the accumulated transpiration, DM, and yield at high salinity levels (S2 and S3). Furthermore, α was also the highest-impact parameter for DM and yield under different root distributions, but the highest-impact parameters for transpiration were ω_c, α, and θ_s under R1, R2, and R3, respectively. Nitrogen application could be neglected when considering the interactive effects of nitrogen application, salinity level, and root distribution on the transpiration, DM, and yield. Additionally, the mean values and uncertainties of the transpiration, DM, and yield were similar in all scenarios, except S3, which showed a sharp decrease in the mean values. We suggest determining the above eight parameters (α, n, ω_c, Pi, SSF, θ_r, θ_s, and TSCF) and the saturated vertical hydraulic conductivity (K_s) based on rigorous calibrations with direct or indirect local measurements using economical methods (e.g., a literature review), with limited observations for other parameters when using the SWAP model and other similar agro-hydrological models.     

Temperature determinants of plant-soil-air mercury relationships

Using the Arrhenius thermodynamic equation, which relates rates of processes to temperature through the quantity E _a , the ‘Heat (or Energy) of Activation’, we have evaluated the thermal relationships for several parameters of Hg cycling. It is shown that release from isolated leaves (shoots) of Hg⁰ is a two-step process with a higher E _a value below 21 °C than above (28 vs 14 kcal mol^?1). Open field air Hg measurements over a mixed stand of grasses and other plants in volcanic soil show strikingly similar behavior to detached organs. Mercury release from volcanic soil was uniform over a wide temperature range, resembling plant and open field emissions above 18 to 21°C with anE _a value of 13 kcal · mol^?1. We conclude that Hg release below 18 to 21 °C is limited by a physiological process, whereas above that range, release is controlled by the physical process of vaporization itself. Plant concentration of total Hg from 5 to 33 °C (air temperature), is a more complex function involving direct accumulation and re-release of Hg⁰ from the atmosphere, release from tissue storage, and root uptake with reduction.