Leaf Area Research Papers - Academia.edu (original) (raw)

This paper presents the effect of hydric stress on Select sunflower hybrid grown under near-neutral and acid soil conditions. The experiment was conducted in green - house with sunflower plants grown in PVC tubs filled with: near- neutral... more

This paper presents the effect of hydric stress on Select sunflower hybrid grown under near-neutral and acid soil conditions. The experiment was conducted in green - house with sunflower plants grown in PVC tubs filled with: near- neutral soil (pH = 6.2 ) (I), acid soil (pH = 5.27) (II) and ferti-lized acid soil ((phosphorus (100 kg/ha), potassium (100 kg/ha)

Summary. In this study, effect of salinity with different osmotic potential on shoot length, total fresh and dry weight, amounts of organic (proline) and inorganic (K+ and Na+) substance of leaf tissue, the Na+/K+ ratio, and leaf area,... more

Summary. In this study, effect of salinity with different osmotic potential on shoot length, total fresh and dry weight, amounts of organic (proline) and inorganic (K+ and Na+) substance of leaf tissue, the Na+/K+ ratio, and leaf area, relative water content (RWC) and leaf osmolality in two maize (Zea mays L., var. intendata, C.6127 and DK.623) cultivars which are grown

Various aspects of the water economy were investigated for a range of herbaceous species varying in relative growth rate. Plants were grown in a growth chamber with a non-limiting supply of water and nutrients, and the rate of... more

Various aspects of the water economy were investigated for a range of herbaceous species varying in relative growth rate. Plants were grown in a growth chamber with a non-limiting supply of water and nutrients, and the rate of transpiration, short-term intercellular CO2 concentration and long- term carbon isotope discrimination (∆) in the leaves were determined. No correlation was found between the relative growth rate of these species, and the transpiration rate per unit leaf area, the intercellular CO2 concentration and the 13 C-discrimination. There was a positive correlation, however, with the rate of water uptake per unit root weight. From these observations we infer that the previously observed differences in photosynthetic nitrogen-use efficiency, the rate of photosynthesis per unit leaf nitrogen, can not be explained by variation in intercellular CO2 concentration. These data were also used to analyse correlations between ∆ and both growth parameters and chemical composition...

Eight accessions of swordbean (Canavalia gladiata (Jacq.) DC.) were collected from eight agroclimatic regions of Tamil Nadu, India. A portion of the collected seeds of accessions will be deposited in NBPGR, New Delhi. The most pronounced... more

Eight accessions of swordbean (Canavalia gladiata (Jacq.) DC.) were collected from eight agroclimatic regions of Tamil Nadu, India. A portion of the collected seeds of accessions will be deposited in NBPGR, New Delhi. The most pronounced differences in agrobotanical characters were observed in seed germination percentage, plant height, number of branches per plant, number of leaves (180th day) per plant,

O trabalho foi realizado com o objetivo de avaliar a produção de B. decumbens cv. Basilisk e B. brizantha, cultivares Marandu e Xaraés, sob diferentes níveis de sombreamento. Utilizou-se delineamento em blocos casualizados com esquema de... more

O trabalho foi realizado com o objetivo de avaliar a produção de B. decumbens cv. Basilisk e B. brizantha, cultivares Marandu e Xaraés, sob diferentes níveis de sombreamento. Utilizou-se delineamento em blocos casualizados com esquema de parcelas subdivididas, considerando os níveis de sombreamento (0, 50, 70%) como parcela e as espécies ou cultivares como subparcelas. Sementes das gramíneas foram postas a germinar em bandejas e transplantadas (três plântulas por vaso). Foram realizados quatro cortes em cada subparcela. Antes de cada corte, mediram-se a altura de planta e a área foliar de quatro folhas em cada planta e quantificou-se o número de perfilhos vivos por vaso. Após a colheita, as plantas foram separadas em lâmina, colmo + bainha e material morto para determinação da produção de matéria seca. Para produção de matéria seca total, calcularam-se a produção média em cada um os cortes e a produção total. No último corte, avaliou-se a massa seca de raízes. As interações signific...

Strawberry cultivar 'Rapella'grown in a glasshouse responded to shade with reductions in leaf area, number of leaves, crowns and inflorescences and shoot dry weight. There was no apparent interaction of shading and salinity on... more

Strawberry cultivar 'Rapella'grown in a glasshouse responded to shade with reductions in leaf area, number of leaves, crowns and inflorescences and shoot dry weight. There was no apparent interaction of shading and salinity on vegetative growth. Shading depressed the ...

Transpiration rates were measured in a flooded population of Phragmites australis ssp. altissima in a wetland located in El Hondo Natural Park (southeastern Spain) during the growing season of 2000. The heat balance method for measuring... more

Transpiration rates were measured in a flooded population of Phragmites australis ssp. altissima in a wetland located in El Hondo Natural Park (southeastern Spain) during the growing season of 2000. The heat balance method for measuring sap flow was used to calculate the rate of water transpiration on a whole-stem basis. Four series of measurements were carried out in selected weeks in May, June, August and October. Structure, biomass and leaf area index of the reed population were simultaneously quantified in order to scale transpiration on a plot-area basis.Overall, transpiration flux was high during the sampling period and showed a typical diurnal pattern with a maximum at about midday. Mean transpiration was highest at the end of June coinciding with the peak of reed growth and with the maximum leaf area both at individual and plot scales. Rates decreased abruptly in October, in parallel with the advanced foliar senescence. The variation of both midday and integrated daily transpiration is significantly related to that of the air temperature on clear days. Cloudy and rainy days exert a pronounced effect on water loss by decreasing transpiration. Our results highlight the potential use of the sap-flow method to measure transpiration in reed ecosystems and the relevance of this flux for the water balance in wetlands in semi-arid environments. Thus, it is suggested that water management in these areas could be favoured by acquiring high-quality experimental data.

The cold stress effect on early vigour and photosynthesis efficiency was evaluated for five industrial chicory varieties with contrasting early vigour. The relationships between the growth and physiological parameters were assessed. The... more

The cold stress effect on early vigour and photosynthesis efficiency was evaluated for five industrial chicory varieties with contrasting early vigour. The relationships between the growth and physiological parameters were assessed. The varieties were examined at three growth temperatures: 16 (reference), 8 (intermediate) and 4 °C (stress). The effect was measured using physiological processes (growth, photosynthesis, chlorophyll a fluorescence), and pigment content. The analysis of the measured growth parameters (dry leaf and root mass, and leaf area) indicated that temperature had a significant effect on the varieties, but the overall reaction of the varieties was similar with lowering temperatures. The photosynthesis and chlorophyll a fluorescence measurements revealed significant changes for the photosynthesis (maximum net photosynthesis, quantum efficiency, light compensation point and dark respiration) and chlorophyll a fluorescence parameters (photochemical and non-photochemical quenching) with lowering temperatures for Hera and Eva, two extremes in youth growth. No significant differences could be found between the extremes for the different temperatures. The pigment content analysis revealed significant differences at 4 °C in contrast to 16 and 8 °C, especially for the xanthophyll/carotenoid pool, suggesting a protective role. Subsequently, the relationship between the physiological processes was evaluated using principal component analysis. At 4 °C, 2 principal components were detected with high discriminating power for the varieties and similar classification of the varieties as determined in the growth analysis. This provides a preview on the possible relationships between photosynthesis and growth for industrial chicory at low temperatures.

P-containing nutrient solutions at concentrations of 5, 20 and 40 ppm, applied through a hydroponics system, provided induced systemic resistance (ISR) against Sphaerotheca fuliginea in young cucumber plants. Protection was expressed as a... more

P-containing nutrient solutions at concentrations of 5, 20 and 40 ppm, applied through a hydroponics system, provided induced systemic resistance (ISR) against Sphaerotheca fuliginea in young cucumber plants. Protection was expressed as a significant reduction (up to 92% compared with control) in the mildewed leaf area. ISR was also expressed as a 53–91% reduction in the number of S. fuliginea conidia per infected leaf area as determined on leaves 1(first true leaf) and 2, at 9 days after inoculation, and on leaves 1–3 at 12 days after inoculation. A concentration of 20 ppm P in the hydroponics solution was found to be optimal for ISR. The optimal P concentration enhanced the uptake and increased the content of Ca in the leaves by 50% compared with the controls. Once the fungus had been established, root-applied P did not affect well-developed colonies, but, foliar application of 1% solution of mono-potassium phosphate (MKP) effectively protected the foliage against powdery mildew, regardless of the P concentration in the nutrient solutions. This treatment was persistent up to 21 days after inoculation, it significantly inhibited powdery mildew development and caused a reduction of 72.3% in sporulation of the fungus as compared with the control. The results suggest different mechanisms for the two phenomena and highlight the role of P in ISR.

In vitro produced leaves of the apple rootstock M26 were infected with Agrobacterium tumefaciens strain GV3 101 containing a binary vector carrying the nptII gene and the rolA gene on the T-DNA. Four transformed clones were obtained from... more

In vitro produced leaves of the apple rootstock M26 were infected with Agrobacterium tumefaciens strain GV3 101 containing a binary vector carrying the nptII gene and the rolA gene on the T-DNA. Four transformed clones were obtained from 433 infected leaves. Two of the transformed clones had a single copy and two had double copies of the T-DNA integrated. In all the four transformed clones the T-DNA was integrated at different positions in the plant chromosomal DNA. All transformed plants exhibited reduced stem growth compared to untransformed control plants. Three of the clones also showed reduced internode length and two of these exhibited reduced leaf area, shoot dry weight, root dry weight and plant dry weight compared to the control plants. No correlation between copy number and plant phenotype was shown.

Soil application of synthetic Fe(III)-chelates, mainly those derived from ethylendiamine di(o-hydroxyphenylacetic) acid (ED-DHA) and ethylendiamine di(2-hydroxy-4-methylphenylacetic) acid (EDDHMA), is the most effective, but the most... more

Soil application of synthetic Fe(III)-chelates, mainly those derived from ethylendiamine di(o-hydroxyphenylacetic) acid (ED-DHA) and ethylendiamine di(2-hydroxy-4-methylphenylacetic) acid (EDDHMA), is the most effective, but the most expensive practice used to correct iron deficiency in plants growing on calcareous soils. Previous studies that compared the effectiveness of EDDHA/Fe 3+ and EDDHMA/Fe 3+ always used commercial products and their results are contradictory. In this study, the effectiveness of commercial EDDHA/Fe 3+ and EDDHMA/Fe 3+ fertilizers to correct iron chlorosis in three different crops (sunflower, peach and pear) was compared using doses calculated with the actual content of chelated iron determined by HPLC. The effectiveness of the Fe(III)-chelate derived from the ethylenediamine di(2-hydroxy-5sulfophenylacetic) acid (EDDHSA), that recently has been marketed as iron fertilizer, was also tested in the sunflower and pear experiments. For the three experiments, sev...