Influence Of Water Deficit Research Articles

Effects of cover crops and irrigation on ‘Tempranillo’ grapevine and berry physiology: an experiment under the Mediterranean conditions of Southern Portugal

In addition to irrigation, other viticultural practices such as soil management can be applied to improve grapevine (Vitis vinifera L.) quality responses and attenuate unfavourable environmental conditions. Cover crops in the interrow of irrigated vineyards change the dynamics of water extraction and it is expected that the patterns of vines’ water relations will be modified, also changing their productive responses. This study took place over two seasons in ‘Tempranillo’ grapevines in a vineyard in South Portugal, where a cover crop was sown in the inter-rows of half the study area (SCC) while maintaining resident vegetation in the remaining (RV). Five water regime treatments were applied: full irrigation (200 mm irrigation amount–I200); moderate irrigation (150 mm–I150); deficit irrigation (100 mm–I100); ultra-deficit irrigation (50 mm–I50); rainfed (I0). Measurements of predawn leaf water potential (ΨPD), stomatal conductance (gs), photosynthetic rate (An), and transpiration rate (E) were made during the final stages of the growth cycle. Data of soil water availability, yield and growth variables, and berries and wine composition were also used. Significant interactions between the effect of soil management and water regime were observed on ΨPD. A water competition effect exerted by the cover crop could be responsible for reduced water loss and carbon assimilation, whenever Spring rain is lower and/or the cover crop biomass development is not controlled. Differences in gs and An observed at midday and late measurements reflect the influence of the daily increase of atmospheric water demand. Stomatal closure of grapevines was less affected in plots of higher soil water storage capacity. The correlation between ΨPD and gs was higher in the midday and late measurements, pointing to the regulation of stomatal response in response to water availability and daily environmental conditions. Principal components analysis (PCA) evidenced an influence of water deficit on metabolic responses that benefit fruit and wine quality. The cluster analysis (CA) revealed that no significant cluster of cases was clearly controlled by soil management or water regime in the first season but, in the second, drier season, significant clustering more irrigation- than soil management-controlled showed that a predominant influence of irrigation should be expected for ‘Tempranillo’ grapevines grown under dry Mediterranean conditions.

A habitat-based approach to determining the effects of drought on aridland bird communities

Abstract Aridland breeding bird communities of the United States are among the most vulnerable to drought, with many species showing significant population declines associated with decreasing precipitation and increasing temperature. Individual breeding bird species have varied responses to drought which suggests complex responses to changes in water availability. Here, we evaluated the influence of water deficit, an integrative metric of drought stress, on breeding bird communities within 3 distinct aridland habitat types: riparian, pinyon-juniper, and sagebrush shrubland. We used 12 years of breeding bird survey data from 11 national parks and monuments in the Northern Colorado Plateau Inventory and Monitoring Network (NCPN). We used a multivariate community-level approach to test for the effect of annual water deficit on the bird communities in the 3 habitats. We found that bird communities responded to water deficit in all 3 habitat types, and 70% of the 30 species–habitat combinations show significant relationships between density and variation in water deficit. Our analyses revealed that the direction and magnitude of species responses to water deficit were habitat-dependent. The habitat-specific responses we observed suggest that the adaptive capacity of some species depends on the habitat in which they occur, a pattern only elucidated with our habitat-based approach. The direction and magnitude of the relationships between predicted densities and annual water deficit can be used to predict the relative sensitivity of species within habitat climate changes. These results provide the first attempt to determine how the indirect effect of changes in water availability might affect aridland breeding birds in distinct habitat types. Linking breeding bird density to annual water deficit may be valuable for predicting changes in species persistence and distribution in response to climate change.

Glutathione and ethylene biosynthesis reveal that the glume and lemma have better tolerance to water deficit in wheat

As senescence progresses, the sensitivity of wheat organs to plant hormones during the grain-filling stages cannot be ignored. Especially under water deficit situation, non-leaf organs (spikes) have better photosynthesis and drought-tolerance traits than flag leaves. However, the mechanism of ethylene synthesis in wheat organs under water deficit remains unclear. We have studied the influence of water deficit in wheat flag leaves and spike bracts on photosynthetic parameters and on the expression of key enzymes involved in the ethylene biosynthesis pathway during the late grain-filling stages. More stable chlorophyll content (Chl), maximum PSII quantum yield (Fv/Fm), nonphotochemical quenching (NPQ) and maximal efficiency of PSII photochemistry under light adaptation (Fv’/Fm’) were observed in the spike bracts than that in the flag leaves during the late grain-filling stages. In addition, the activity of glutathione reductase (GR), γ-glutamylcysteine synthetase (γ-ECS), 1-aminocyclopropane-1-carboxylic (ACC) acid synthase (ACS), and ACC oxidase (ACO) induced ethylene synthesis and influenced plant growth. Further analysis of genes encoding cysteine-ethylene related proteins (γ-ECS, GR, ACO, ACS1, and ASC2) demonstrated that ear organs and flag leaves exhibited different expression patterns. These findings will facilitate future investigations of the regulatory senescence response mechanisms of cysteine interaction with ethylene in wheat under conditions of drought stress.

Physiological responses to water deficiency in bread wheat (Triticum aestivum L.) lines with genetically different leaf pubescence.

Studying the relationship between leaf pubescence and drought resistance is important for assessing Triticum aestivum L. genetic resources. The aim of the work was to assess resistance of common wheat genotypes with different composition and allelic state of genes that determine the leaf pubescence phenotype. We compared the drought resistance wheat variety Saratovskaya 29 (S29) with densely pubescent leaves, carrying the dominant alleles of the Hl1 and Hl3 genes, and two near isogenic lines, i: S29 hl1, hl3 and i: S29 Hl2aesp, with the introgression of the additional pubescence gene from diploid species Aegilops speltoides. Under controlled conditions of the climatic chamber, the photosynthetic pigments content, the activity of ascorbate-glutathione cycle enzymes and also the parameters of chlorophyll fluorescence used to assess the physiological state of the plants photosynthetic apparatus were studied in the leaves of S29 and the lines. Tolerance was evaluated using the comprehensive index D, calculated on the basis of the studied physiological characteristics. The recessive state of pubescence genes, as well as the introduction of the additional Hl2aesp gene, led to a 6-fold decrease in D. Under the water deficit influence, the fluorescence parameters profile changed in the lines, and the viability index decreased compared with S29. Under drought, the activity of ascorbate peroxidase, glutathione reductase and dehydroascorbate reductase in the line i: S29 hl1, hl3 decreased 1.9, 3.3 and 2.3 times, in the line i: S29 Hl2aesp it decreased 1.8, 3.6 and 1.8 times respectively, compared with S29. In a hydroponic greenhouse, line productivity was studied. Compared with S29, the thousand grains mass in the line i: S29 hl1, hl3 under water deficit was reduced. The productivity of the line i: S29 Hl2aesp was significantly reduced regardless of water supply conditions in comparison with S29. Presumably, the revealed effects are associated with violations of cross-regulatory interactions between the proteins of the trichome formation network and transcription factors that regulate plant growth and stress response.

Influence of water deficit on morphological, physiological and growth of Balsa (Ochroma pyramidale)

Water is one of the main factors that influence the growth and development of plants. Balsa (Ochroma pyramidale) is a fast-growing tropical tree species with a great demand in the international market. The influence of soil, water deficit on morphological, physiological, and the growth of Balsa (Ochroma pyramidale) with and without irrigation was investigated. For this study, four random repetitions were carried out in a randomized complete block design. The plants were irrigated regularly with furrow irrigation. The timing of irrigation was based on the soil, water potential, according to treatment criteria. All pots were irrigated at 15, 30, 45, 60 and 75 days. Genomic DNA of O. Pyramidale was identified by ERIC-PCR and RAPD, while phylogenetic tree was determined using the UPGMA method. The results showed that leave number, shoot number, stem elongation and stem diameter were affected significantly (P 0.05) were observed, while stomata length remained high (> 20 µm) and stomata diameter was decreased during evaluation days in plants without irrigation compared to control. DNA of eight plants isolated showed different band profiles. In conclusion, the parameters evaluated can be used as a measure of water stress, growers should be careful when using O. Pyramidale in both nursery and orchards where water scarcity is present.

Influence of water deficit and defoliation managements on post‐drought recovery and persistence of smooth bromegrass

AbstractIn arid and semiarid regions, successful recovery from drought may be of more economic significance than plant productivity during a dry season. This research was conducted to investigate the effects of pre‐drought irrigation and defoliation managements (seed and forage managements) on post‐drought recovery of diverse smooth bromegrass (Bromus inermis Leyss.) genotypes, and to identify growth traits associated with persistence and recovery as indices for selecting superior genotypes. Thirty‐six genotypes were field evaluated in two separate experiments of seed and forage managements during 2013–2015 under well‐watered and deficit irrigation regimes. In the fourth year (2016), irrigation was withheld from both moisture regimes for two months (almost complete senescence) and then plants were re‐watered to find the effect of prolonged drought stress on post‐drought recovery. Pre‐drought irrigation increased persistence of genotypes relative to the well‐watered treatment in the seed management experiment. In the seed management trial, genotypes had greater recovery under deficit irrigation when compared to forage management counterpart. There was no significant difference between seed and forage management experiments under the well‐watered regime in this respect. Positive correlations were observed between recovery after prolonged drought and total aerial biomass, persistence, and winter growth vigor under both irrigation regimes. Superior genotypes were identified as having more productivity, better recovery, higher persistence, and drought tolerance.

Effects of chemical fertilizer reduction with organic fertilizer application under water deficit on photosynthetic characteristics and yield of cotton

<p indent=0mm>Fixed position experiments were conducted in 2017 and 2018, and split plot arrangement with the main treatment for full irrigation (W₁) with irrigation amount was 4800 cubic meters per hectare and deficit irrigation (W₂) was 2400 cubic meters per hectare, and the secondary treatment including treatments without fertilization (CK), single application of chemical fertilizer (CF), 75% chemical fertilizer with 25% organic fertilizer (M₁), 50% chemical fertilizer with 50% organic fertilizer (M₂), and 25% chemical fertilizer with 75% organic fertilizer (M₃). The effects of chemical fertilizer reduction and organic fertilizer application on photosynthetic characteristics and yield of cotton were studied to provide theoretical basis for rational utilization of organic fertilizer and reduction of chemical fertilizer input under water deficit. Under deficit irrigation, leaf area index (LAI), net photosynthetic rate (<italic>P</italic>_n), stomatal conductance (<italic>G</italic>_s), above-ground dry matter accumulation and seed yield of cotton were all lower than that under full irrigation, while irrigation water productivity (IWP) and intercellular CO₂ concentration (<italic>C</italic>_i) were higher. The chemical fertilizer reduction combined with application of organic fertilizer could effectively improve the LAI after the full squaring stage, improve <italic>P</italic>_n and <italic>G</italic>_s of cotton in all stage, promote the accumulation of vegetative and reproductive organs dry matter, improve its transfer to the reproductive organs, improve the IWP and seed yield, and also increase the moisture content of soil surface in the period of full boll stage and boll opening stage. The effects among different organic fertilizer treatments on LAI, <italic>P</italic>_n and seed yield were all presented as M₁ > M₂ > M₃, and under the treatment of M₁, the average seed cotton yield of two years increased compared with CF and CK by 6.9% and 62.1% respectively. Whereas, the effects under deficit irrigation were presented as M₂ > M₁ > M₃, and the two years’ average seed yield increased by 19.9% and 79.3% respectively compared with CF and CK under M₂. Chemical fertilizer reduction and organic fertilizer application were beneficial to increase the yield of seed cotton under water deficit, and alleviate the influence of water deficit on cotton growth and development, M₂ (50% fertilizer +50% organic fertilizer) was the best treatment.

Influence of different water deficit levels during grain filling on yield and total polyphenols content in spring wheat cultivars

Wheat (Triticum aestivum L.) is often affected by abiotic stress such as high temperatures and water deficit. Due to this, grain yield can be reduced by a water deficit and an inadequate grain filling as well as affect synthesis of polyphenolic compounds. The aim of this study was to determine the influence of water deficit on yield in spring wheat cultivars during grain filling stage, and evaluate total polyphenol content in whole wheat flour. Experiments were conducted at two locations during 2016-2017 growing season, using a randomized complete block design with a split-plot arrangement, with 12 treatments consisting of three irrigations levels and four spring wheat cultivars. In Site 1, interaction (P < 0.05) was obtained between water deficit level and cultivar, ‘Pantera-INIA CL’ achieved highest grain yield (10.5 Mg ha-1), with a well-watered treatment, while ‘Lasana’ reached lowest grain yield (8.5 Mg ha-1), with a severe water deficit. However, water deficit did not affect significantly (P > 0.05) grain yield in Site 2, and differences were observed only between cultivars (P < 0.05) in a range of 6.1 to 7.1 Mg ha-1. Total polyphenol content was not affected by water deficit, differences were only observed between cultivars in both locations (P < 0.05). However, cultivars showed a higher total polyphenol content in Site 1. Water deficit level did not negatively influence yield of four wheat cultivars evaluated in Site 2. While in Site 1, only yield of ‘Lasana’ and ‘Pantera-INIA CL’ was reduced, with severe water deficit.

Drought-related hot summers: A joint probability analysis in the Iberian Peninsula

Droughts and hot extremes are major sources of risk to several socio-economic activities and their impacts are expected to increase under future global warming. Moreover, the simultaneous or sequential occurrence (compound events) of different climate extremes may lead to the amplification of the associated impacts. Even though the latest efforts in assessing hot and dry extremes and their interactions, the development of models describing the joint behavior of climate extremes is still a challenge. To contribute to the understanding of these compound events, we propose to assess the probability of extremely hot summer days in the Iberian Peninsula (IP) being preceded by drought events in spring and early summer, based on their joint probability distribution through copula theory. The precursor drought hazard was characterized by the Standardized Precipitation Evaporation Index (SPEI) for the months of May, June and July for different timescales (3-, 6- and 9-months). The Number of Hot Days per month (NHD) summed over the months of July and August were considered for modelling. The dependence structure between SPEI and NHD was very well identified for the most of the IP's regions by asymmetrical copulas with upper tail dependence (except in northwestern regions), suggesting that compound hot and dry extremes are strongly associated. The results show that the transition from previous wet to dry regimes increases substantially the probability of exceeding summer NHD extreme values, depending on the region and the drought timescale and target month. The results suggest a spatial heterogeneity over the IP when characterizing the influence of water deficits on following summer extreme temperatures, whereas northeastern, western and central regions were found to be the regions more prone to summer hot extremes induced by dryness, in contrast to southwestern, northwestern and southeastern regions (depending on the month and the timescale). This study provides estimates of the probability of drought-related hot extremes in the summer of the IP for different regions, which could be an important tool for responsible authorities to mitigate the impacts magnified by the interactions between the different hazards.

Phosphorus in Spring Barley and Italian Rye-Grass Biomass as an Effect of Inter-Species Interactions under Water Deficit

With global warming, the problem of soil water deficit is growing in Central Europe, including Poland, and the use of catch crops is recommended to mitigate climate changes. This study aimed to determine the influence of water deficit on phosphorus (P) content and accumulation in the above-ground biomass of spring barley and Italian rye-grass growing separately and in the mixture, and on the inter-species interactions between these crops. The study was based on a pot experiment established in accordance with the additive design. The experimental factors were as follows: A. water supply of the plants: an optimal dose and a dose reduced by 50% in relation to the optimal dose, and B. the sowing type: barley sown as a single species, rye-grass sown as a single species, and barley with rye-grass catch crop. Based on the P accumulation in plant biomass, the relative yield of barley and rye-grass, the total relative yield, and the competitive equilibrium index were determined. Water deficit had no effect on the P content in the plants, but it reduced the P accumulation in barley stems, leaves and spikes, as well as in rye-grass stems and leaves, from the emergence to the end of plants’ growing period, both when the plants were sown as a single species and as a mixture. Barley was a stronger competitor than rye-grass. Inter-species competition occurred at the stem elongation and heading of barley. The intensification of inter-species competition for P under water deficit conditions should be taken into account when recommending the undersowing of barley with rye-grass for sustainable agriculture.

Quantifying the influence of water deficit on root and shoot growth in wheat using X-ray Computed Tomography.

The potential increased frequency and severity of drought associated with environmental change represents a significant obstacle to efforts aimed at enhancing food security due to its impact on crop development, and ultimately, yield. Our understanding of the impact of drought on crop growth in terms of plant aerial tissues is much more advanced than knowledge of the below-ground impacts. We undertook an experiment using X-ray Computed Tomography that aimed to support measurements of infrared gas exchange from plant shoots with quantification of 3D root architecture traits and the associated soil structural characteristics. Winter wheat (cv. Zebedee) was assessed at two early growth stages (14 and 21 days) under four water treatments (100, 75, 50 and 25 % of a notional field capacity (FC) and across two soil types (sandy loam and clay loam)). Plants generally grew better (to a larger size) in sandy loam soil as opposed to clay loam soil, most likely due to the soil structure and the associated pore network. All plants grew poorly under extreme water stress and displayed optimal growth at 75 % of FC, as opposed to 100 %, as the latter was most likely too wet. The optimal matric potential for root and shoot growth, inferred from the water release curve for each soil type, was higher than that for photosynthesis, stomatal conductance and transpiration suggesting root and shoot growth was more affected by soil water content than photosynthesis-related characteristics under water deficit conditions. With incidences of drought likely to increase, identification of wheat cultivars that are more tolerant of these conditions is important. Studies that consider the impact of water stress on both plant shoots and roots, and the role of the soil pore system such as this offer considerable potential in supporting these efforts.

Drought stress improves the composition of secondary metabolites in safflower flower at the expense of reduction in seed yield and oil content

Abiotic stresses like drought may modulate the synthesis of plants' secondary metabolites, with various pharmacological effects. In this study, the influence of water deficit was determined on safflower (Carthamus tinctorius L.) seed yield and oil content as well as antioxidant activity and phenolic and flavonoid compounds of both seed and flower for their industrial application. Eight safflower genotypes were planted in the field in two separate experiments under normal and water deficit conditions in a randomized complete block design. Agronomic traits of the genotypes were measured and their polyphenolic compounds were evaluated using liquid chromatography analysis. Results indicated that averaged over all genotypes and under normal irrigation conditions, seed yield and antioxidant capacity of seed extracts were 74% higher and 2.32 times of those under drought stress conditions, respectively. In contrast, under water stress, flower extracts had 2-fold antioxidant capacity at the expense of a significant decrease in seed yield, seed oil content, and antioxidant capacity of the seeds. The most abundant polyphenolic components in flowers of most genotypes which accumulated due to water stress were vanillic and caffeic acids. While in seeds, rutin and quercetin were more accumulated under normal irrigation regime. Interestingly, three components of apigenin, luteolin, and ferulic acid were not detected in flower extract of any genotypes in both irrigation regimes. The contrasting status of seeds vs. flowers under two environmental conditions were depicted by multivariate data analysis. Based on the principal component analysis, under normal irrigation regime, the higher antioxidant activity of the seeds (seed preferability) was correlated with total content and compounds of flavonoids. In contrast, in water deficit condition, the higher antioxidant activity of the flowers (flower preferability) was correlated with total phenolic content and vanillic, caffeic, and p-coumaric acids. Finally, one breeding line may be introduced with high seed yield and quality under both irrigation regimes, which its higher drought tolerance is possibly due to the induced synthesis of caffeic acid and quercetin.

ASSESSMENT OF PHYSIOLOGICAL AND MORPHOLOGICAL TRAITS OF PLANTS OF THE GENUS Fragaria UNDER CONDITIONS OF WATER DEFICIT – A STUDY REVIEW

The genus Fragaria belongs to the Rosaceae family. The most popular representatives of this species are the strawberry (Fragaria × ananassa Duch.) and wild strawberry (Fragaria vesca L.), whose taste and health benefits are appreciated by a huge number of consumers. The cultivation of Fragaria plants is widespread around the world, with particular emphasis on the temperate climate zone. Increasingly occurring weather anomalies, including drought phenomena, cause immense losses in crop cultivation. The Fragaria plant species are very sensitive to drought, due to the shallow root system, large leaf area and the high water content of the fruit. There have been many studies on the influence of water deficit on the morphological, biochemical and physiological features of strawberries and wild strawberries. There is a lack of research summarizing the current state of knowledge regarding of specific species response to water stress. The aim of this study was to combine and compare data from many research carried out and indicate the direction of future research aimed at improving the resistance of Fragaria plants species to stress related to drought. These plants show patterns of response to stress caused by drought, such as: osmotic adjustment, reduction of transpiration and photosynthesis, and increased efficiency of water use. Drought also causes significant changes in the composition and palatability of the fruit of the Fragaria plant species.

Effect of Water Deficit on Morphoagronomic and Physiological Traits of Common Bean Genotypes with Contrasting Drought Tolerance

Water deficit is considered one of the most limiting factors of the common bean. Understanding the adaptation mechanisms of the crop to this stress is fundamental for the development of drought-tolerant cultivars. In this sense, the objective of this study was to analyze the influence of water deficit on physiological and morphoagronomic traits of common bean genotypes with contrasting drought tolerance, aiming to identify mechanisms associated with tolerance to water deficit. The experiment was carried out in a greenhouse, arranged in a randomized complete block 4 × 2 factorial design, consisting of four common bean genotypes under two water regimes (with and without water stress), with six replications. The morphoagronomic and physiological traits of four cultivars, two drought-tolerant (IAPAR 81 and BAT 477) and two drought-sensitive (IAC Tybatã and BRS Pontal), were measured for 0, 4, 8, and 12 days, under water deficit, initiated in the phenological stage R5. Water-deficit induced physiological changes in the plants, altering the evaluated morphoagronomic traits. The drought tolerance of cultivar BAT 477 is not only a direct result of the low influence of water deficit on its yield components, but also a consequence of the participation of multiple adaptive physiological mechanisms, such as higher intrinsic water use efficiency, net photosynthesis rate, transpiration, carboxylation efficiency, stomatal conductance, and intracellular concentration of CO2 under water deficit conditions. On the other hand, cultivar IAPAR 81 can be considered drought-tolerant for short water-deficit periods only, since after the eighth day of water deficit, the physiological activities decline drastically.

Effects of water deficit and different nitrogen fertilizer treatments on the quality of wheat for Chinese fresh white noodles and steamed bread and the composition of storage proteins.

Noodles and steamed bread are popular wheat products consumed worldwide, particularly in China and other Asian countries. We performed the first comprehensive study of the influence of water deficits and different nitrogen fertilizer applications on two elite Chinese bread wheat cultivars, Zhongmai 175 and Jimai 22, which are distinct in gluten strength. These wheat cultivars were tested to determine the qualities that are optimal for the production of Chinese fresh white noodles (CFWN) and northern-style Chinese steamed bread (NCSB), and storage protein composition. Water deficit and high nitrogen (N) fertilizer application promoted total grain protein content and the accumulation of gliadins and glutenins, while low N resulted in the opposite results. Water deficit and high N fertilizer in Jimai 22, with medium-to-strong gluten strength significantly improved NCSB and CFWN qualities. The quality of CFWN under low N, and that of NCSB under both high and low N conditions, was significantly reduced. However, NCSB and CFWN quality in Zhongmai 175 with weak-to-medium gluten strength was not significantly affected by water deficit and different N fertilizer applications. Grain subproteome analysis revealed that considerable cultivar-specific gliadins and glutenins showed significant accumulation changes in response to water deficit and high / low N fertilizer treatment, which could be responsible for NCSB and CFWN quality changes under different treatments. Water deficit and high / low N fertilizer treatments caused changes in cultivar-specific storage protein composition, resulting in differences in the accumulation of gliadins, glutenins, and the quality of NCSB and CFWN. © 2019 Society of Chemical Industry.

Photosynthetic parameters of Juglans nigra trees are linked to cumulative water stress

The influence of water deficits and drought on tree physiological processes, growth, and survival has been the focus of substantial research efforts and debate over the past decades, but there is still a need to quantitatively link finer scale mechanistic explanations of the influence of water status with the physiological responses of trees, particularly for those past the sapling stage. Hence, the objective of this study was to link accumulated water stress during the growing season to leaf physiological response mechanisms of Juglans nigra L. trees. Results showed that trees subjected to higher cumulative water stress had lower maximum light-saturated photosynthesis (Amax), initiated net photosynthesis at higher light levels (Ic), and displayed reduced effectiveness of CO2 fixation per photons absorbed (Qe) at the bottom and upper positions along the vertical canopy gradient. Results suggest that water stress integral (Sψ), a variable that takes into account accumulated water deficits, would be useful to help future research efforts aimed at investigating responses to drought in trees past the sapling stage.

The effect of drought conditions on sweet orange (Citrus sinensis) plants infected with citrus tristeza virus (CTV)

Brazil is one of the world’s largest producers of citrus. However, production is challenged due to biotic and abiotic factors limiting crop health. The aim of this work was to evaluate the influence of water deficit in sweet orange (Citrus sinensis) cv. Pera Bianchi inoculated with citrus tristeza virus (CTV). Two isolates of CTV were used, one causing severe symptoms (Forte Rolândia) and the second causing mild symptoms (Pera IAC), grafted on Rangpur lime (Citrus limonia) and Swingle citrumelo [Citrus paradisi x Poncirus trifoliata], and the indicator sweet orange Pera Bianchi, free of virus, and healthy controls containing only the indicator budwood. The water regime for the plants was field capacity or 50% field capacity. After five months of controlled irrigation, biochemical variables were measured (protein, proline content and catalase activity), and real-time RT-PCR amplification of the virus was performed for detection and quantification of viral titer. Differences were observed in the total protein content and proline, with greater accumulation in plants maintained under water deficit. There was no effect of drought on the population of viral isolates, but the plants held at field capacity and inoculated with the severe isolate had a higher viral titer.

Fluorescence and Growth of Eggplant under Irrigation Levels and Silicon Doses

Aims: The study was conducted to evaluate the fluorescence and growth of eggplant under influence of water deficit and silicon doses.&#x0D; Study Design: The design was a randomized complete block design, in a 5 x 2 factorial arrangement, with four replications and one plant per plot, totaling 40 experimental units.&#x0D; Length and Place of Study: The research was implemented between September and November 2016, in a greenhouse of the Center of Science and Technology Agrifood, at the Federal University of Campina Grande (UFCG / CCTA), Campus of Pombal-PB, Brazil.&#x0D; Methods: Doses of 0, 75, 150, 225 and 300 mg L-1 of silicon and the irrigation slides of 50 and 100% of real evapotranspiration - ETr were used, which were obtained by weighing the pots daily in order to keep the weight close to the field capacity.&#x0D; Results: The use of 50% level of the ETr provides reductions of 5.58; 7.92 and 6.84% of fluorescence in the initial, maximum and quantum yield of the photosystem. The fresh and dry mass of the stem presented the maximum productivity (140.8 and 48.1 g) in the plants irrigated with 100% Etr and treated with doses of 106 and 110 mg L-1 of Si.&#x0D; Conclusion: The fluorescence and biomass of the eggplant plants is reduced with the decrease in irrigation level; while the application of silicon does not result in increment in the fluorescence and dry mass of the leaf. The 100% irrigation level of the ETr associated with the application of 108 mg L-1 of silicon resulted in the best results in stem mass accumulation.

Changes in yield and nutritive value of red clover (Trifolium pratense L.) and Festulolium (Festulolium braunii (K. Richt) A. Camus) under drought stress

The aim of the research was to assess the impact of water stress on the yield and content of basic nutrients in the biomass of Trifolium pratense and Festulolium braunii cultivated in pure stand and in mixture. A pot experiment was carried out in 2012–2014, at two levels of soil moisture: well-watered and drought stress. The study showed that stress significantly reduced the dry matter yield (DMY), the most in T. pratense, followed by mixture, and F. braunii. The effect of drought stress on the nutritive value was considerable less pronounced than the influence on DMY. No significant influence of water deficit on crude protein, crude fibre and crude ash contents was found, but only on water-soluble carbohydrate and crude fat content in one year of the study. It was found, that under drought stress T. pratense is more suitable for cultivation in the mixture with F. braunii than in pure stand, due to a lower reduction of DMY and no adverse effect of water deficiency on yield quality.

Development of woody plants phenotyping sys tem with the help of machine vision and spectral analysis algorithms

Phenotyping is a modern technology that allows registering and analyzing data about living systems phenotypes in automatic mode. In recent years a high-efficiency higher plants phenotyping with the aim of deep study of the physiological and biochemical bases of their functioning, as well as selection of new high-yielding and stress-resistant varieties has acquired significant development. It is based on adaptation and introduction of modern information approaches such as algorithms of «computer vision» and allows receiving detailed information about plants phenomes at various organization levels. One of the unreached research sections in this field is tree plant cuttings phenotyping, which represents a great practical interest. In this work the system of phenotyping of green stem cuttings of woody plants Thuja occidentalis L. (Smaragd), Juniperus scopulorum Sarg. (Blue Arrow), Picea Abies L., H. Karst. was developed using machine vision algorithms and spectral analysis. A modular phenomics complex was created. It consist of phenomics box, plant cultivation system, lighting and watering systems, as well as system of registration and processing of RGB-images, including software. This complex has been tested in the laboratory and in field conditions. The initial testing of the phenomics complex was carried out. It showed that the data of changes in the pixel distribution of RGB-images by wavelengths can be the basis for estimating the size and physiological state of stem cuttings of woody plants. It was shown that the shift of the spectral curve of the reflected light into the long-wave area under the influence of water deficit allows to non-invasive and statistically reliably register the death of some cells. At the same time, statistically reliable distinctions have not been revealed at testing of influence of phytohormones (auxins and brassinosteroids) on rooting of stem cuttings of coniferous species. The obtained results have a fundamental practical significance and can be used in the research of physiological processes in higher plants, ornamental crop production and forestry.