Leaf Nutritional Status Research Articles

Mechanisms of storage and detoxification of Al in two tropical mistletoes

Passovia ovata (Pohl ex DC.) Kuijt and Struthanthus polyanthus Mart. are hemiparasitic mistletoes that can grow on Al-accumulating and Al-excluding woody species in the Brazilian Cerrado. It is unclear to what extent this hemiparasitic lifestyle implies facultative Al accumulation by the mistletoes and if so, what are the Al tolerance mechanisms in these species. Using a field-work experiment composed by two facultative Al-accumulating mistletoe species (P. ovada and S. polyanthus) infecting Al-accumulating (Miconia albicans (Sw.) Steud.) and Al-excluding (Byrsonima verbascifolia (L.) DC.) hosts, we (1) investigated Al accumulation and leaf nutritional status of the mistletoes, (2) characterized the storage sites and the forms of Al accumulated in their leaves, and (3) determined differences in levels of simple organic acids associated with Al detoxification. Leaf nutrients and Al accumulation in mistletoes followed the host elements availability. In both mistletoe species infecting the Al-accumulating host M. albicans, Al was mainly allocated to the phloem fibres, and Al-citrate was the main form of Al. Contrastingly, in the hosts’ leaves Al was present mainly in the form of oxalate complexes. When growing on B. verbascifolia, the Al excluding host, the two mistletoes neither showed symptoms of Al storage nor formation of Al-organic acid complexes. In conclusion, mistletoes growing on Al-accumulating trees tolerate high Al tissue levels by allocating Al in phloem fibres and by its chelation with citrate.

Effects of Variable Rate Nitrogen Application on cv. Barbera Performance: Vegetative Growth and Leaf Nutritional Status

Variable rate application of vineyard inputs in field parcels characterized by different levels of vigor and/or yield is one of the most promising applications of precision agriculture. In a four-year study, we provided ground-truthing of three different vigor levels (L = low, M = medium, and H = high) derived pre-trial from Normalized Difference Vegetation Index (NDVI) values determined by remotely sensed imagery (5 m pixel resolution) in a small Barbera vineyard (0.64 ha). Each vigor level was subjected to three fertilization strategies (S) consisting of no N supply (C, 0 kg/ha), standard supply (S, 60 kg/ha), and variable-rate application (VRA) delivering 0, 60, and 120 kg/ha to H, M, and L vines, respectively. Post-trial effects were assessed by taking another NDVI satellite image at the same resolution and by adding proximal sensing performed with the MECS-VINE sensor yielding the estimation of a canopy index (CI). Ground-truthing was based on recording main vine growth parameters and leaf nutritional status. Results show that vine balance of L vines was optimal. Variability among vigor levels was significantly reduced in years 3 and 4, while mean effects related to fertilization strategy were not significant and very few S × V and S × Y interactions were found. However, when the ground-truthing assessment was compared with the CI index values, it was very clear that VRA was able to reduce variability among vigor levels (CV = 1.42%) versus standard fertilization at 60 kg/ha (8.20%).

Foliar applications of a legume-derived protein hydrolysate elicit dose-dependent increases of growth, leaf mineral composition, yield and fruit quality in two greenhouse tomato cultivars

Abstract The use of natural plant biostimulants is proposed as a promising and innovative approach to ensure improved and sustainable yields and product quality. A greenhouse experiment was performed to assess the yield performance, leaf net assimilation of CO 2 , mineral composition of leaves and fruits, and fruit physicochemical quality attributes of two tomato cultivars (Akyra and Sir Elyan) in relation to biostimulant treatments (control or two different concentrations of the legume-derived protein hydrolysate Trainer ® ). Treated tomato plants were sprayed every 10 days with a solution containing 2.5 and 5.0 ml L −1 of biostimulant. Akyra was found to be richest in K, Ca, Mg, lipophilic and hydrophilic antioxidant activities (LAA and HAA), lycopene, total phenolic and total ascorbic acid. Foliar applications of legume-derived protein hydrolysate at 5.0 ml L −1 increased marketable yield of Akyra and Sir Elyan by modulating yield components differently depending on cultivars: higher number of fruits in Akyra and increase of fruit mean weight in Sir Elyan. Improved yield performance with biostimulant foliar applications at the highest rate was related to improved leaf nutritional status (higher K and Mg) and higher net assimilation of CO 2 . The application of legume-derived protein hydrolysate at 5.0 ml L −1 , and to a lesser degree at 2.5 ml L −1 , elicited an increase in antioxidant activities, total soluble solids, mineral composition (K and Mg) as well as bioactive molecules such as lycopene and ascorbic acid, thereby increasing the nutritional and functional quality of the fruits. These findings can assist tomato growers in selecting cultivars and application dose for protein hydrolysate to complement high crop productivity with optimal fruit quality.

Diagnostic Leaf Nutrient Norms and Identification of Yield-Limiting Nutrients of Mango in Eastern Plateau and Hill Region of India

ABSTRACTThe leaf nutritional status of mango orchards was assessed using diagnosis and recommendation integrated system (DRIS). The DRIS norms, which showed higher variance and lower coefficients of variation, are found to have greater diagnostic precision. As per DRIS indices, a relative deficiency for magnesium, zinc, and boron corresponding to relative sufficiency for calcium, nitrogen, phosphorus, sulfur, and potassium was detected in 9-year-old mango orchards. For the younger orchards (6–7 year old), the order of requirement of nutrients was found to be calcium > sulfur > potassium > boron > nitrogen > phosphorus > magnesium > zinc. Boron was found as the most yield-limiting elements in all age group of plants. When the DRIS indices were compared on the basis of soil pH, calcium and magnesium were most yield-limiting nutrients below pH 5.5, while nitrogen, zinc, and boron were found to be most limiting above pH 5.5.

Evaluating Leaf Nutritional Status and Fruit Quality Attributes of "Sultani" Cultivar Fresh Fig Fruit Under Sinai Conditions

Evaluating Leaf Nutritional Status and Fruit Quality Attributes of "Sultani" Cultivar Fresh Fig Fruit Under Sinai Conditions

Ground-truthing of remotely sensed within-field variability in a cv. Barbera plot for improving vineyard management

Background and Aims Precision viticulture encompasses a series of techniques from remote to proximal sensing for describing and exploiting within-vineyard variability. Our aim was to assess how vigour mapping associated with detailed ground-truthing can provide guidelines for more sustainable vineyard management. Methods and Results A satellite image taken with a 5 m-pixel resolution on a mature, small-sized (0.6 ha) cv. Barbera vineyard at full canopy made it possible to build a vigour map on the assessment of normalised difference vegetation index (NDVI) distinguishing low-vigour (LV), medium-vigour (MV) and high-vigour (HV) areas of equal surface. Detailed single-vine records for vegetative growth (shoot length, leaf area and pruning mass), yield components (bud fruitfulness, yield per vine and bunch and berry mass) and grape composition were recorded within each vigour class at harvest; leaf nutritional status and ripening curves were monitored for the same classes. While NDVI showed a close correlation to several vegetative, yield and grape composition parameters, LV vines exhibited excellent performance for remunerative yield (3.2 kg/vine, or a potential yield of 13.3 t/ha) and full ripening with maintenance of adequate TA. Both MV and HV showed excessive vigour and cropping leading towards incomplete ripening. Conclusions The combination of NDVI mapping and detailed ground-truthing allows the identification of the vigour level for the greatest vineyard efficiency and the definition of an appropriate strategy either to exploit current variability through selective harvesting or to correct variability through variable rate application of nitrogen. Significance of the Study The NDVI mapping via low-resolution satellite images associated with ground-truthing appears to be a straightforward protocol to increase sustainable vineyard management.

Hormonal and Nutritional Features in Contrasting Rootstock-mediated Tomato Growth under Low-phosphorus Nutrition.

Grafting provides a tool aimed to increase low-P stress tolerance of crops, however, little is known about the mechanism (s) by which rootstocks can confer resistance to P deprivation. In this study, 4 contrasting groups of rootstocks from different genetic backgrounds (Solanum lycopersicum var. cerasiforme and introgression and recombinant inbred lines derived from the wild relatives S. pennellii and S. pimpinellifolium) were grafted to a commercial F1 hybrid scion and cultivated under control (1 mM, c) and P deficient (0.1 mM, p) conditions for 30 days, to analyze rootstocks-mediated traits that impart low (L, low shoot dry weight, SDW) or high (H, high SDW) vigor. Xylem sap ionic and hormonal anlyses leaf nutritional status suggested that some physiological traits can explain rootstocks impacts on shoot growth. Although xylem P concentration increased with root biomass under both growing conditions, shoot biomass under low-P was explained by neither changes in root growth nor P transport and assimilation. Indeed, decreased root P export only explained the sensitivity of the HcLp rootstocks, while leaf P status was similarly affected in all graft combinations. Interestingly, most of the nutrients analyzed in the xylem sap correlated with root biomass under standard fertilization but only Ca was consistently related to shoot biomass under both control and low-P, suggesting an important role for this nutrient in rootstock-mediated vigor. Moreover, foliar Ca, S, and Mn concentrations were (i) specifically correlated with shoot growth under low-P and (ii) positively and negatively associated to the root-to-shoot transport of the cytokinin trans-zeatin (t-Z) and the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC), respectively. Indeed, those hormones seem to play an antagonistic positive (t-Z) and negative (ACC) role in the rootstock-mediated regulation of shoot growth in response to P nutrition. The use of Hp-type rootstocks seems to enhance P use efficiency of a commercial scion variety, therefore could potentially be used for increasing yield and agronomic stability under low P availability.

Comparative performance of some pear cultivars on southern aspect of wet temperate zone in Western Himalaya

The studies were conducted at experimental farm of Temperate Horticultural Research Station, Kotkhai to compare the performance of 12 pear cultivars for their fruit quality and leaf nutritional status. Various cultivars under study differed significantly with respect to their fruit physico-chemical characteristics and leaf nutrient contents. Cultivar Red Bartlett had highest fruit length (82.37 mm, whereas, fruit diameter (76.65 mm) and fruit weight (193.50 g) were recorded significantly higher in cultivar Max Red Bartlett. Cultivar Starking Delicious exhibited highest total soluble solids (16.05°Brix), TSS/acid ratio (66.27) and minimum titratable acidity (0.28%). The highest fruit firmness (15.40 lbs/inch2) was recorded in cv. Beurre Hardy, whereas significantly higher total sugars content (5.95%) and reducing sugars content (5.03) were registered by Doyenne du Comice and Kala Hathi, respectively. The cultivars Aval Number, Max Red Bartlett and Flemish Beauty exhibited highest leaf nitrogen (2.31%), phosphorus (0.212%) and potassium (1.96%) contents, respectively. On the basis of fruit physicochemical characteristics, Red Bartlett, Max Red Bartlett, Starking Delicious, Doyenne du Comice and Beurre Hardy were found suitable for cultivation in zone III of Himachal Pradesh.

English

The present study was carried out during 2012 and 2013 seasons to study the effect of pre-harvest foliar application of chitosan (a natural beta-1-4-linked glucosamine polymer) at two concentrations 250 and 500 ppm on vegetative tree growth, fruit yield and quality as well as leaves chemical composition of Washington navel orange trees grown under two locations. As for growth parameters (shoot length, leaves number, and leaves area), the results revealed that chitosan treatments had insignificant effect. Meanwhile, it had a significant improvement on most of the studied fruit characters and leaf chemical constituents, that is, pigments, sugars, total soluble phenols, total free amino acids, endogenous plant hormones “IAA, ABA and GA3” as well as leaf nutritional status “N, P, K, Zn, Ca, B and Si”. Generally, pre-harvest chitosan applications mostly had pronounced positive effects on improving navel orange quality, that is, fruit weight, firmness and T.S.S.%, especially at the rate 500 ppm. Key words: Citrus, chitosan, growth characters, fruit quality, total chlorophyll, sugar, total soluble sugar (TSS).

Root-to-Shoot Hormonal Communication in Contrasting Rootstocks Suggests an Important Role for the Ethylene Precursor Aminocyclopropane-1-carboxylic Acid in Mediating Plant Growth under Low-Potassium Nutrition in Tomato.

Selection and breeding of rootstocks that can tolerate low K supply may increase crop productivity in low fertility soils and reduce fertilizer application. However, the underlying physiological traits are still largely unknown. In this study, 16 contrasting recombinant inbred lines (RILs) derived from a cross between domestic and wild tomato species (Solanum lycopersicum × Solanum pimpinellifolium) have been used to analyse traits related to the rootstock-mediated induction of low (L, low shoot fresh weight) or high (H, high shoot fresh weight) vigor to a commercial F1 hybrid grown under control (6 mM, c) and low-K (1 mM, k). Based on hormonal and ionomic composition in the root xylem sap and the leaf nutritional status after long-term (7 weeks) exposure low-K supply, a model can be proposed to explain the rootstocks effects on shoot performance with the ethylene precursor aminocyclopropane-1-carboxylic acid (ACC) playing a pivotal negative role. The concentration of this hormone was higher in the low-vigor Lc and Lk rootstocks under both conditions, increased in the sensitive HcLk plants under low-K while it was reduced in the high-vigor Hk ones. Low ACC levels would promote the transport of K vs. Na in the vigorous Hk grafted plants. Along with K, Ca, and S, micronutrient uptake and transport were also activated in the tolerant Hk combinations under low-K. Additionally, an interconversion of trans-zeatin into trans-zeatin riboside would contribute to decrease ACC in the tolerant LcHk plants. The high vigor induced by the Hk plants can also be explained by an interaction of ACC with other hormones (cytokinins and salicylic, abscisic and jasmonic acids). Therefore, Hk rootstocks convert an elite tomato F1 cultivar into a (micro) nutrient-efficient phenotype, improving growth under reduced K fertilization.

Growth of northern deciduous trees under increasing atmospheric humidity: possible mechanisms behind the growth retardation

Increasing atmospheric humidity—a climate trend predicted for northern Europe—will reduce water flux through vegetation. Diminished transpirational water flux impacts various physiological processes, causing growth decline in deciduous trees. We propose, based on the results obtained from the long-term free air humidity manipulation experiment, concurrent mechanisms to explain the growth deceleration due to increases in relative air humidity. Reduced atmospheric evaporative demand diminishes nutrient uptake and leads to lower leaf nutritional status and to an unbalanced foliar phosphorus/nitrogen ratio (P:N), resulting in a decline in leaf photosynthetic capacity. Elevated relative humidity induces readjustment of foliar metabolism: disturbed N metabolism, accumulation of starch and changes in secondary metabolite contents probably impair both photosynthetic performance and growth. Increased carbohydrate content in the leaves suggests that sink strength of trees is reduced under elevated humidity. As a consequence of the stress, foliar development is hindered, observed at individual leaf or whole-tree foliage levels, lowering production potential of trees proportionally to their foliar area. Larger investments in stem xylem in relation to foliage cause an increase in the ratio of non-photosynthetic to photosynthetic tissues, leading to larger maintenance respiration costs determined by the volume of parenchymatous tissue. An increase in the proportion of living parenchyma cells in relation to dead xylem elements in sapwood additionally enhances respiration costs. Disproportionate changes in hydraulic versus stomatal conductance become a critical factor in the case of weather extremes, which limit canopy conductance and may induce dysfunction of the hydraulic system. Increasing environmental humidity creates favourable conditions for development of pathogens, increasing frequency of fungal damage.

Influences of aspect and tillage on two winegrape cultivars on Mount Etna

ABSTRACTThe effect of minimum tillage on two autochthonous Vitis vinifera L. varieties, namely Nerello mascalese and Carricante, established on the eastern and northern aspect slopes of the volcano Mount Etna in Sicily, was evaluated over two seasons. The objective was to determine whether conventional tillage and minimum tillage affect the vegetative growth, bud fertility, total leaf area, leaf nutritional status and fruit yield components. The ratio of bunches/retained buds was strongly influenced by aspect. Yield per vine was significantly different within cultivars and seasons depending on cultivar, tillage treatment and aspect. Due to its natural plasticity in marginal conditions, yields were consistently higher in Nerello mascalese. The yield reduction with minimal tillage was excessive in Carricante. As a consequence of the yield reduction in the second season, total soluble solids in particular were increased in Nerello mascalese. Linear discriminant analysis revealed the highest discrimination values for cultivar and the lowest ones for tillage.

English

Production of orchids is important in floriculture, and nitrogen is one of the nutrients most required by plants. However, there is little information on nitrogen leaf analysis of these orchids. We evaluated the nitrogen fertilization on leaf nutritional status and on the production of dry mass and develop a diagnostic sheet for the orchid Phalaenopsis. Five concentrations of N (0.0, 0.068, 0.136, 0.204 and 0.272 g L-1) in the form of ammonium nitrate, was compared for two hybrids (Phalaenopsis Taisuco Swan and Phalaenopsis Pink Chiffon). The plants were grown in pots in a greenhouse. Foliar fertilization was done fortnightly during the initial 120 days, and thereafter weekly for over 120 days. From 90 days after onset of the foliar applications, leaf green index with monthly measurements up to 240 days of application was evaluated. Dry matter shoot and the N content in the first and second newly expanded leaf was determined after 240 days. Based on polynomial relationship, a higher dry mass was achieved by applying 0.10 to 0.16 g L-1 nitrogen. The second newly expanded leaf was the most appropriate plant tissue for assessing nutritional status of Phalaenopsis and foliar concentration nitrogen was optimal at 23-28 g kg-1. Key words: Orchidaceae, nitrogen fertilization, seedlings.

Biogeographic patterns of nutrient resorption from Quercus variabilis Blume leaves across China.

The variation in nutrient resorption has been studied at different taxonomic levels and geographic ranges. However, the variable traits of nutrient resorption at the individual species level across its distribution are poorly understood. We examined the variability and environmental controls of leaf nutrient resorption of Quercus variabilis, a widely distributed species of important ecological and economic value in China. The mean resorption efficiency was highest for phosphorus (P), followed by potassium (K), nitrogen (N), sulphur (S), magnesium (Mg) and carbon (C). Resorption efficiencies and proficiencies were strongly affected by climate and respective nutrients concentrations in soils and green leaves, but had little association with leaf mass per area. Climate factors, especially growing season length, were dominant drivers of nutrient resorption efficiencies, except for C, which was strongly related to green leaf C status. In contrast, green leaf nutritional status was the primary controlling factor of leaf nutrient proficiencies, except for C. Resorption efficiencies of N, P, K and S increased significantly with latitude, and were negatively related to growing season length and mean annual temperature. In turn, N, P, K and S in senesced leaves decreased with latitude, likely due to their efficient resorption response to variation in climate, but increased for Mg and did not change for C. Our results indicate that the nutrient resorption efficiency and proficiency of Q.variabilis differed strongly among nutrients, as well as growing environments. Our findings provide important insights into understanding the nutrient conservation strategy at the individual species level and its possible influence on nutrient cycling.

Organic Wastes Use in Horticulture: Influences on Nutrient Supply and Apple Tree Growth

The application of fertilizers derived from agroindustrial by-products, represents an interesting opportunity in organic farming. The composition of such inputs includes complex molecules, which strongly influence their effectiveness in providing the optimal nutrient availability and improving crop performances. The aim of the present study was to determine the nutrient release rate of different organic fertilizers and amendments and their effects on shoot growth, fruit production, leaf nutritional status, root biomass and morphology. In a two-years pot trial, two organic fertilizers produced with dried fungal biomass (DFB) and vinasse of sugar beet pulp (VN) and two amendments obtained from fermented animal sewage (SE) and composted olive husks plus grapevine waste (OG), were applied on apple rooted cuttings. One set of plant were not fertilised and acted as Control. The application of DFB, VN and SE increased nitrogen concentration in the soil and in the leaves, supported higher fruit number and enhanced plant growth above and below ground compared to OG and Control. The effect on root growth was positively correlated with nitrogen mineralization rate. For OG treatment, soil electric conductivity negatively influenced root branching frequency, indicating a potential risk of stress due to salinity excess. Original Research Article Polverigiani et al.; IJPSS, Article no. IJPSS.2014.003 359

Fertilization effect on trees and fruits characteristics and leaf nutrient status of apricots which are grown at Cacak region (Serbia)

The influence of cattle manure, complex NPK (15:15:15) and calcium ammonium nitrate (CAN) mineral fertilisers and natural zeolite commercially named “Agrozel” on tree growth, productivity, fruit physico-chemical features and leaf nutritional status of four apricot cultivars was studied under acidic soil conditions in Western Serbia. Tree growth and yield performances were increased by CAN and NPK applications in general, whereas manure promoted the highest fruit weight. All fertilisers, except NPK promoted flesh firmness. Application of NPK improved primary fruit metabolites (soluble solids and total sugars content and titratable acidity), whereas Agrozel induced the highest levels of secondary metabolites [total phenolic content (TPC), total flavonoid content (TFC) and total antioxidant capacity (TAC)]. The highest tree vigor and the lowest productivity were observed in ‘Biljana’, while ‘Harcot’ had low tree vigor and high productivity. The largest fruits and highest flesh firmness were observed in ‘Vera’ and ‘Biljana’, respectively. Fruits of ‘Aleksandar’ are rich source in soluble solids content and TFC, ‘Biljana’ in total sugars, ‘Vera’ also in total sugars and TAC, while ‘Harcot’ had the highest levels of titratable acidity and TPC. Fertiliser treatments positively affected leaf macro- and micronutrients content, except leaf N and K at 120 days after full bloom (DAFB). All fertilisers induced excessive leaf P content, and deficiency of other nutrients in most cases. Leaf K and Mn contents, partially N and Cu, were not consistent. The highest imbalances and better balances among macronutrients were found when trees of ‘Vera’ and ‘Harcot’ fertilized with manure, respectively, whereas these characteristics among micronutrients were observed when trees of ‘Aleksandar’ and ‘Biljana’ fertilized with CAN, respectively. Leaf of ‘Harcot’ showed better balance values among macronutrients, and ‘Biljana’ among micronutrients.

Effect of Calcium and Boron Foliar Spray on Fruit Quality and Leaf Nutritional Status of "Kelsey" Plum Trees

Effect of Calcium and Boron Foliar Spray on Fruit Quality and Leaf Nutritional Status of "Kelsey" Plum Trees

Using leaf optical properties to detect ozone effects on foliar biochemistry

Efficient methods for accurate and meaningful high-throughput plant phenotyping are limiting the development and breeding of stress-tolerant crops. A number of emerging techniques, specifically remote sensing methods, have been identified as promising tools for plant phenotyping. These remote sensing methods can be used to accurately and rapidly relate variations in leaf optical properties with important plant characteristics, such as chemistry, morphology, and photosynthetic properties at the leaf and canopy scales. In this study, we explored the potential to utilize optical (λ=500-2,400nm) near-surface remote sensing reflectance spectroscopy to evaluate the effects of ozone pollution on photosynthetic capacity of soybean (Glycine max Merr.). The research was conducted at the Soybean Free Air Concentration Enrichment (SoyFACE) facility where we subjected plants to ambient (44nL L(-1)) and elevated ozone (79-82nL L(-1) target) concentrations throughout the growing season. Exposure to elevated ozone resulted in a significant loss of productivity, with the ozone-treated plants displaying a ~30% average decrease in seed yield. From leaf reflectance data, it was also clear that elevated ozone decreased leaf nitrogen and chlorophyll content as well as the photochemical reflectance index (PRI), an optical indicator of the epoxidation state of xanthophyll cycle pigments and thus physiological status. We assessed the potential to use leaf reflectance properties and partial least-squares regression (PLSR) modeling as an alternative, rapid approach to standard gas exchange for the estimation of the maximum rates of RuBP carboxylation (V c,max), an important parameter describing plant photosynthetic capacity. While we did not find a significant impact of ozone fumigation on V c,max, standardized to a reference temperature of 25°C, the PLSR approach provided accurate and precise estimates of V c,max across ambient plots and ozone treatments (r (2)=0.88 and RMSE=13.4μmolm(-2) s(-1)) based only on the variation in leaf optical properties and despite significant variability in leaf nutritional status. The results of this study illustrate the potential for combining the phenotyping methods used here with high-throughput genotyping methods as a promising approach for elucidating the basis for ozone tolerance in sensitive crops.

Humidity‐driven changes in growth rate, photosynthetic capacity, hydraulic properties and other functional traits in silver birch (Betula pendula)

AbstractA study was performed on saplings of silver birch (Betula pendula Roth) growing at the free air humidity manipulation site, which was established to investigate the effect of increased air humidity on tree performance and canopy functioning. The aim of the experiment was to simulate the impact of the increasing atmospheric humidity on forest ecosystems predicted for northern Europe. Artificially elevated relative humidity (RH), which causes transpirational flux to decrease, diminished nutrient supply to the foliage; leaf nitrogen content, phosphorus content and P:N ratio decreased. The changes in leaf nutritional status brought about a considerable decline in both photosynthetic capacity (Amax, Vcmax, Jmax) and tree growth rate. The manipulation induced diverse changes in tree hydraulic architecture and other functional traits. Different segments of the soil‐to‐leaf water transport pathway responded differently: leaf hydraulic conductance (KL) decreased, while hydraulic conductance of root systems (KR) and leaf‐specific conductivity of stem‐wood increased in response to elevated RH. Humidification caused the Huber values of stems to increase, thus reflecting changes in allocation patterns; relatively more resources were allocated to vascular tissue and less to foliage. The elevated RH induced substantial changes in specific leaf area (increased), branch‐ (decreased) and stem‐wood density (decreased). The observed responses suggest that the expected climate‐change‐induced increase in the growth rate of trees at northern latitudes (boreal areas) due to the earlier start of the growing season in spring or higher carbon assimilation rate could be smaller or null if temperature rise is accompanied by a rise in atmospheric absolute humidity.

Application of arbuscular mycorrhizal fungi on the production of cut flower roses under commercial-like conditions

The objective of this work was to study the influence of two arbuscular mycorrhizal fungi (AMF) - Glomus mosseae (Nicol. & Gerd.) Gerd. & Trappe, and G. intraradices (Schenck & Smith) - on cut flower yield of rose (Rosa hybrida L. cv. Grand Gala) under commercial-like greenhouse conditions. Flower production was positively influenced by G. mosseae inoculation. Both inocula tested caused low levels of mycorrhizal root colonization, with higher percentages in Rosa associated with G. mosseae. Significant improvement of plant biomass or leaf nutritional status was not detected in inoculated plants probably due to the low symbiosis establishment. However, G. mosseae induced an early flowering and slightly increased number of cut flowers relative to non-mycorrhizal controls. It is suggested that an altered carbohydrate metabolism could contribute to this positive effect. Low colonization of rose roots supports the idea that more effort is required to ensure successful application of AMF in ornamental production systems.