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Oil in fruits and seeds is an important source of calories and essential fatty acids for humans. This specifically holds true for olive oil, which is appreciated for its superior nutritional value. Most olive orchards are cultivated to produce oil, which are the outcome of fruit yield and oil content. Little information is available on the effect of nitrogen (N) on olive fruit oil content. The response of olive trees to different rates of N was therefore studied in soilless culture (3 years) and commercial field (6 years) experiments. In both experiments, fruit N level and oil biosynthesis were negatively associated. Fruit N increased in response to N fertilization level and was inversely related to fruit load. The negative correlation between fruit N and oil content was more pronounced under high fruit load, indicating sink limitation for carbon. These results agree with those reported for oilseed crops for which a trade-off between oil and protein was proposed as the governing mechanism for the negative response to elevated N levels. Our results suggest that the protein/oil trade-off paradigm cannot explain the noticeable decrease in oil biosynthesis in olives, indicating that additional mechanisms are involved in N-induced inhibition of oil production. This inhibition was not related to the soluble carbohydrate levels in the fruit, which were comparable regardless of N level. These results emphasize the importance of balanced N nutrition in oilolive cultivation to optimize production with oil content. [ABSTRACT FROM AUTHOR]

This paper presents the electrical performance of organic photovoltaic modules (OPVs) on top of a polyethylene covered greenhouse high tunnel in a Mediterranean climate. Modules from a previous study were kept on the tunnel and monitored together with new modules with improved connectors installed on the greenhouse roof and on frames adjacent to the greenhouse. Measured module power conversion efficiencies ranged from 1% to 3%. The typical combined output of the modules across the tunnel roof were 105Wh on a sunny day and 81Wh on a cloudy day. Module burn-in period was about 15 days, losing around 36% of its initial efficiency. Ts80 lifetimes ranged from 7 days to 94 days. Tunnel integration was shown to accelerate module degradation. [ABSTRACT FROM AUTHOR]

Detection, analysis, and characterization of low-abundant metabolites remain an unresolved problem in metabolic studies. In this study, we report a novel approach to address this challenge. The current methodology is [...]

Detection, analysis, and characterization of low-abundant metabolites remain an unresolved problem in metabolic studies. In this study, we report a novel approach to address this challenge. The current methodology is [...]

Summary: Steroidal glycoalkaloids (SGAs) are protective metabolites constitutively produced by Solanaceae species. Genes and enzymes generating the vast structural diversity of SGAs have been largely identified. Yet, mechanisms of hormone pathways coordinating defence (jasmonate; JA) and growth (gibberellin; GA) controlling SGAs metabolism remain unclear.We used tomato to decipher the hormonal regulation of SGAs metabolism during growth vs defence tradeoff. This was performed by genetic and biochemical characterisation of different JA and GA pathways components, coupled with in vitro experiments to elucidate the crosstalk between these hormone pathways mediating SGAs metabolism.We discovered that reduced active JA results in decreased SGA production, while low levels of GA or its receptor led to elevated SGA accumulation. We showed that MYC1 and MYC2 transcription factors mediate the JA/GA crosstalk by transcriptional activation of SGA biosynthesis and GA catabolism genes. Furthermore, MYC1 and MYC2 transcriptionally regulate the GA signalling suppressor DELLA that by itself interferes in JA‐mediated SGA control by modulating MYC activity through protein–protein interaction. Chemical and fungal pathogen treatments reinforced the concept of JA/GA crosstalk during SGA metabolism.These findings revealed the mechanism of JA/GA interplay in SGA biosynthesis to balance the cost of chemical defence with growth. [ABSTRACT FROM AUTHOR]

Jojoba (Simmondsia chinensis (Link) Schneider) holds high industrial value and an extended cultivation trend. Despite its increased importance, there is a lack of fundamental information about its metabolic reserves and development. Our objective was to characterise metabolite allocation and fluctuations in the carbohydrate and nutrient balance of jojoba plants, as affected by fruit load and the plant's annual cycle. Metabolite profiles were performed for each organ. Soluble carbohydrates (SC) and starch concentrations were surveyed in underground and aboveground organs of high-yield and fruit-removed plants. Simultaneously, nitrogen, potassium and phosphorus were determined in the leaves to evaluate the plant's nutritional status. We found that sucrose and pinitol were the most abundant sugars in all jojoba organs. Each sugar had a 'preferred' organ: glucose was accumulated mainly in the leaves, sucrose and pinitol in woody branches, and fructose in the trunk wood. We found that fruit load significantly influenced the carbohydrate levels in green branches, trunk wood and thin roots. The phenological stage strongly affected the SC-starch balance. Among the examined minerals, only the leaf potassium level was significantly influenced by fruit load. We conclude that jojoba's nutrient and carbohydrate balance is affected by fruit load and the phenological stage, and describe the organspecific metabolic reserves. [ABSTRACT FROM AUTHOR]

The linkage between K and the development of storage roots in root crops is partially understood, hence this experiment determined some of the mechanisms involved in cassava. The effects of 10, 40, 70, 100, 150 and 200 mg K l−1 fertigation on photosynthetic attributes, soluble carbohydrates, starch, metabolites, growth and yield were studied in a greenhouse. Storage root yield, number of storage roots, stomatal conductance and net photosynthesis reached maximum at 150 mg K l−1. However, soluble carbohydrates and starch in the leaves significantly declined with an increasing concentration of K solution, similarly to the trend of glycerol in the leaves. Conversely, malic acid, citric acid and propionic acid gradually increased reaching maximum at 150, 150 and 70 mg K l−1 respectively. Combined, these results suggest that sugars were transported from the leaves to a stronger sink – the bulking storage roots. This and the increase of intermediate metabolites of tricarboxylic acid cycle provided the energy required for the bulking process and the development of the storage roots. Although the measured parameters indirectly link K to storage root development, they nonetheless form a basis for studies on direct interactions. [ABSTRACT FROM AUTHOR]

Recent increase in demand for agricultural products combined with scarcity of fresh water has motivated increased use of non-conventional water sources for irrigation. Application of water varying in quality dictates adjustment of nitrogen (N) management. The response of bell pepper to a range of different concentrations of N and salinity (NaCl) was evaluated in soilless and field experiments under greenhouse conditions. Pepper plant biomass and yield increased with N and decreased with salinity. Chloride accumulated mainly in the stems and the fraction of Cl in leaves increased as a function of increased exposure to salinity. Increasing N application resulted in reduced Cl uptake and accumulation in pepper organs, including leaves and petioles. Although N significantly reduced Cl content and concentration in leaves and petioles it did not compensate for the negative effects of increasing salinity. This indicates that salinity itself and not Cl − N competition was the limiting factor affecting growth and yield. [ABSTRACT FROM AUTHOR]

The olive tree is generally characterized by relatively low final fruit set consequential to a significant rate of undeveloped pistils, pistil abortion, and flower and fruitlet abscission. These processes are acknowledged to be governed by competition for resources between the developing vegetative and reproductive organs. To study the role of phosphorus (P) nutritional level on reproductive development, trees were grown under four levels of P for three years in large containers. Phosphorus nutritional level was positively related to rate of reproductive bud break, inflorescence weight, rate of hermaphrodite flowers, pistil weight, fruitlet persistence, fruit set and the consequential total number of fruits. The positive impact of P nutrition on the productivity parameters was not related to carbohydrate reserves or to carbohydrate transport to the developing inflorescence. Phosphorous deficient trees showed significant impairment of assimilation rate, and yet, carbohydrates were accumulated in inflorescences at levels comparable to or higher than trees receiving high P. In contrast to female reproductive organs, pollen viability was consistently higher in P deficient trees, possibly due to the enhanced carbohydrate availability. Overall, the positive effect of P on female reproductive development was found to be independent of the total carbohydrate availability. Hence, P is speculated to have a direct influence on reproductive processes. [ABSTRACT FROM AUTHOR]

The involvement of ethylene in fruit ripening is well documented, though knowledge regarding the crosstalk between ethylene and other hormones in ripening is lacking. We discovered that AUXIN RESPONSE FACTOR 2A (ARF2A), a recognized auxin signaling component, functions in the control of ripening. ARF2A expression is ripening regulated and reduced in the rin, nor and nr ripening mutants. It is also responsive to exogenous application of ethylene, auxin and abscisic acid (ABA). Over-expressing ARF2A in tomato resulted in blotchy ripening in which certain fruit regions turn red and possess accelerated ripening. ARF2A over-expressing fruit displayed early ethylene emission and ethylene signaling inhibition delayed their ripening phenotype, suggesting ethylene dependency. Both green and red fruit regions showed the induction of ethylene signaling components and master regulators of ripening. Comprehensive hormone profiling revealed that altered ARF2A expression in fruit significantly modified abscisates, cytokinins and salicylic acid while gibberellic acid and auxin metabolites were unaffected. Silencing of ARF2A further validated these observations as reducing ARF2A expression let to retarded fruit ripening, parthenocarpy and a disturbed hormonal profile. Finally, we show that ARF2A both homodimerizes and interacts with the ABA STRESS RIPENING (ASR1) protein, suggesting that ASR1 might be linking ABA and ethylene-dependent ripening. These results revealed that ARF2A interconnects signals of ethylene and additional hormones to co-ordinate the capacity of fruit tissue to initiate the complex ripening process. [ABSTRACT FROM AUTHOR]

Irrigation of tomato ( Solanum lycopersicum Mill) plants with brackish (including saline) water improves fruit taste and reduces yields. Salinity additionally leads to toughening of tomato fruit skin, the causative mechanism for which is unknown. The aim of this study is to characterize the effects of salinity on tomato fruit skin texture. Tomato (cherry and full size) plants were irrigated with fresh water (control, ED = 1.01 dS m −1 ) and saline water (up to 12.61 dS m −1 ). Organoleptic assessment was compared to the force needed to puncture the cherry tomato fruit skin and to specific skin dry weight. The skin structure of cherry and full-size tomatoes was characterized by light microscopy. Chemical characterization of cell walls building the skin of cherry tomatoes was conducted by Raman micro-spectroscopy. Skin penetration force was found to be linearly correlated with its specific weight and with consumers' perceived thickness. Fruit histology revealed a linear correlation between thickness of the sub-epidermis and salinity of the irrigation water. The tougher tomato skin obtained under conditions of salinity is attributed to increased number of hypodermal cell layers rather than to changes in cell wall composition. [ABSTRACT FROM AUTHOR]

Sweet pepper ( Capsicum annuum L.) is an excellent source of bioactive nutrients. Manganese is a crucial micro-element for plant nutrition, has a role in photosynthesis, and is a cofactor in antioxidant enzymes. Pepper fruit grown under a protective environment are nevertheless exposed to high temperatures during the summer that cause oxidation-related heat damage to the pericarp beneath the fruit skin. We demonstrate that high temperatures significantly modify total antioxidant activity in peppers at different ripening stages. Pepper cultivars differ in their antioxidant activity, which was correlated with their ability to cope with high temperature damages. Manganese applied to pepper plants modifies antioxidant activity, but different cultivars responded differently to the manganese application. In summary, pepper fruit grown under temperature stress will possess higher antioxidant activity than those grown at lower temperatures and will therefore be of higher nutritional value for human consumption. Agronomic practices such as growing conditions or manganese supply may alter, in a cultivar-specific manner, the antioxidant activity and the nutritional values of the crop. [ABSTRACT FROM AUTHOR]

Temporal responses to drought and nitrogen stresses were studied on wheat ( Triticum aestivum ) seedlings subjected to drying and re-watering cycles. Growth traits were monitored in a soil column experiment conducted with two water and two nitrogen levels. Leaf area, dry weight, carbon and nitrogen mass, root/shoot ratio, specific leaf nitrogen, photosynthesis, transpiration, and water and nitrogen use efficiencies dynamically responded to water and nitrogen stresses as a function of the degree of specific stress over the growing period. Specific leaf nitrogen was critical for improving photosynthetic activity, and influenced water use efficiency positively but nitrogen use efficiency negatively, indicating a distinct trade-off between water and nitrogen use efficiencies. Subsequent to irrigation and the immediate alleviation of severity of water and nitrogen stresses, photosynthesis and transpiration recovered gradually over a period of 3–4 days. Extent of recovery was influenced by the degree of stress prior to re-watering and the re-watering cycles. Ignoring the dynamics of recovery from stress led to notable errors in numerical simulations of the dynamics of soil water and plant transpiration. [ABSTRACT FROM AUTHOR]

BACKGROUND: Quinclorac (3,7-dichloro-quinoline-carboxylic acid) is a selective herbicide widely used to control annual grasses and certain broadleaf weeds. Echinochloa phyllopogon (Stapf) Koss. is the most noxious grass weed in California rice fields and has evolved resistance to multiple herbicides with different modes of action. A quinclorac-resistant (R) E. phyllopogon biotype found in a Sacramento Valley rice field where quinclorac has never been applied was investigated. RESULTS: Resistant to susceptible (S) GR50 (herbicide rate for 50% growth reduction) ratios ranged from 6 to 17. The cytochrome P450 inhibitor malathion (200 mg L−1) caused R plants to become as quinclorac susceptible as S plants. Quinclorac rapidly (6 HAT) stimulated ethylene formation in S plants, but only marginally in R plants. Malathion pretreatment did not reduce ethylene formation by quinclorac-treated S and R plants. Activity of β-cyanoalanine synthase (β-CAS) in tissue extracts was 2-3-fold greater in R than in S plants, and incubation of shoot extracts with 1 mM malathion reduced β-CAS activity by 40% in both biotypes. CONCLUSION: Resistance to quinclorac in R E. phyllopogon involved at least two mechanisms: (a) insensitivity along the response pathway whereby quinclorac induces ethylene production; (b) enhanced β-CAS activity, which should enable greater HCN detoxification following quinclorac stimulation of ethylene biosynthesis. This unveils new resistance mechanisms for this multiple-resistant biotype widely spread throughout California rice fields. Copyright © 2011 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

• Avocado's scion and rootstock can cooperate to avoid salinity damage. • Hass grafted on a salt-tolerant rootstock had more chloroplast-related lipids. • Hass grafted on a salt-tolerant rootstock assimilated more carbon. • The leaf/root sugar ratio of a salt-tolerant tree decreased by salinity exposure. • The roots functioned selectively to moderate salt ion transport. Commercial avocado orchards typically consist of composite trees. Avocado is salt-sensitive, suffering from substantial growth and production depreciation when exposed to high sodium and chloride levels. Salt ions penetrate the roots and are subsequently transferred to the foliage. Hence, understanding distinct physiological responses of grafted avocado plant organs to salinity is of great interest. We compared the ion, metabolite and lipid profiles of leaves, roots and trunk drillings of mature 'Hass' scion grafted onto two different rootstocks during gradual exposure to salinity. We found that one rootstock, VC840, did not restrict the transport of irrigation solution components to the scion, leading to salt accumulation in the trunk and leaves. The other rootstock, VC152, functioned selectively, moderating the movement of toxic ions to the scion organs by accumulating them in the roots. The leaves of the scion grafted on the selective rootstock acquired the standard level of essential minerals without being exposed to excessive salt concentrations. However, this came with an energetic cost as the leaves transferred carbohydrates and storage lipids downward to the rootstock organs, which became a strong sink. We conclude that mutual scion–rootstock relationships enable marked tolerance to salt stress through selective ion transport and metabolic modifications. [ABSTRACT FROM AUTHOR]

Abstract: Glyphosate-resistant cotton (GRC) was introduced experimentally to Israel in 1998. Field and laboratory studies were conducted in 1998–2000 to evaluate the effect of the timing and rates of glyphosate application on cotton development and fruit set. No damage to the vegetative parts of cotton plants was observed when glyphosate was applied over-the-top (OTT) at all growth stages examined. However, glyphosate applied OTT, at the 8–10 leaf stage (late OTT), caused severe damage to the reproductive parts. Cotton grown in different climatic regions responded differently to late OTT application of glyphosate, indicating a strong interaction with environmental conditions. Late OTT application resulted in a development of abnormal flowers, non-dehiscent anthers containing irregularly shaped and less viable pollen grains. In contrast, the stigma and other female organs of treated plants were functional and did not show any injury symptoms. Male-sterile flowers usually produced deformed bolls with one or more degenerated compartments leading to a “moon” or “beak” shape bolls. Bolls developed on the early fruiting branches (5th–10th) of late OTT-treated plants were smaller as compared to those developed at the same position on untreated plants. In general, the cotton plants succeeded to compensate for the early damage caused by glyphosate by producing additional bolls on the upper internodes. These additional bolls did not reach maturity until harvest time. In spite of the visible injury to flowers and bolls, late OTT application did not cause significant yield reduction. Combined late and very late (12–13 leaf stage, before cotton canopy closes) glyphosate application resulted in a significant yield reduction. Further studies are in progress to elucidate the mechanism involved in the glyphosate-induced male sterility in transgenic cotton. [Copyright &y& Elsevier]

• Vegetables are irrigated with waters of variable qualities. • Integrated irrigation, fertilization and salt management vital for sustainability. • Irrigation with water high in salts causes groundwater contamination. • Nitrate is the major pollutant in arid and semi-arid regions. • Desalination can promote strategies for sustainable irrigation. Water-scarcity in dry areas is driving agriculture towards increased utilization of marginal to poor quality water sources for irrigation. This includes groundwater and recycled wastewater that tend to be characterized by high levels of minerals and commonly of problematic salts. Israel has been a global leader in irrigation application efficiency, use of groundwater with relatively high concentrations of salts and recycled municipal wastewater, and recently, in the use of large-scale seawater desalination for human consumption and irrigation. Irrigation with water high in salts has been shown to be unsustainable in many dry regions, mostly due to increasing salinity of soil, subsoil, and groundwater resulting from the application and leaching of salts. We present a summary of the direct effects of salinity on crop production, of its management in vegetable crops, and of the environmental consequences of different salinity management practices. The objective of this review is to provide a fundamental understanding of the advantages and limitations of irrigating vegetable crops as a function of water quality, considering good quality surface and groundwater, saline/brackish water, treated wastewater and desalinated water. The long-term experience of irrigation of annual vegetable and other horticultural crops with diverse water qualities in Israel is reviewed. The environmental implications of irrigation as a function of water salinity, both on a national scale and using a local case study of irrigation with brackish groundwater of vegetables in Israel's Arava Valley, are discussed. Finally, possible management strategies are suggested to reduce environmental consequences of irrigation with water containing salts and address the fundamental question; "can irrigated arid zone vegetable production be sustainable?" [ABSTRACT FROM AUTHOR]

Horticulture nitrogen (N) runoffs are major environmental and health concerns, but current farming practices cannot detect ineffective N applications. Hence, we set to recognize high N conditions and characterize their effects on the physiology of almond trees grown in drainage lysimeters. Water and nutrients mass balances exhibited that N benefitted almond trees in a limited range (below 60 mg N L−1 in irrigation), while higher N conditions (over a 100 mg N L−1) reduced evapotranspiration (ET) by 50% and inherently constrained N uptake. Respectively, whole-tree hydraulic conductance reduced by 37%, and photosynthesis by 17%, which implied that high N concentrations could damage trees. Through gas-chromatography, we realized that high N conditions also affected components of the citric acid cycle (TCA) and carbohydrates availability. Such changes in the metabolic composition of roots and leaves probably interfered with N assimilation and respiration. It also determined the proportions between N and starch in almond leaves, which formed a new index (N:ST) that starts at 0.4 in N deficiency and reaches 0.6–0.8 in optimal N conditions. Importantly, this index continues to increase in higher N conditions (as starch reduces) and essentially indicates to excessive N applications when it exceeds 1.1. • Current mineral diagnoses cannot support precise farming as it will not detect high nitrogen availability. • Disproportionate nitrogen applications compromise the hydraulic conductivity and photosynthetic productivity of trees. • Biochemical functionalities exhibit that nitrogen availability affects the composition and allocation of photosynthates. • Metabolic and mineral analyses form a new nitrogen and starch index (N:ST) to excessive nitrogen fertilization. [ABSTRACT FROM AUTHOR]

Late watergrass [ Echinochloa phyllopogon (Stapf.) Koss.] is a major weed of California rice that has evolved P450-mediated metabolic resistance to multiple herbicides. Resistant (R) populations are also poorly controlled by the recently introduced herbicide penoxsulam. Ratios (R/S) of the R to susceptible (S) GR(50) (herbicide rate for 50% growth reduction) ranged from 5 to 9. Although specific acetolactate synthase (ALS) activity was 1.7 higher in R than in S plants, the enzyme in R plants was about 6 times more susceptible to the herbicide. R plants exhibited faster (2.8 times) oxidative [(14)C]-penoxsulam metabolism than S plants 24 h after treatment. Addition of malathion (P450 inhibitor) enhanced herbicide phytotoxicity and reduced penoxsulam metabolism in R plants. Tank mixtures with thiobencarb (can induce P450) antagonized penoxsulam toxicity in R plants, suggesting penoxsulam may be broken down by a thiobencarb-inducible enzyme. These results suggest E. phyllopogon resistance to penoxsulam is mostly due to enhanced herbicide metabolism, possibly via P450 monooxidation.

Background: Late watergrass [Echinochloa phyllopogon (Stapf.) Koss.] is a major weed of Californian rice that has evolved P450-mediated metabolic resistance to multiple herbicides. Resistant (R) populations are also poorly controlled by the recently introduced herbicide clomazone. The authors assessed whether this cross-resistance was also P450 mediated, and whether R plants also had reduced sensitivity to photooxidation. Understanding mechanism(s) of resistance facilitates the design of herbicide management strategies to delay resistance evolution., Results: Ratios (R/S) of R to susceptible (S) GR(50) were near 2.0. [(14)C]Clomazone uptake was similar in R and S plants. Clomazone and its metabolite 5-ketoclomazone reduced chlorophyll and carotenoids in S more than in R plants. The P450 inhibitors disulfoton and 1-aminobenzo-triazole (ABT) safened clomazone in R and S plants. Disulfoton safened 5-ketoclomazone only in S plants, while ABT synergized 5-ketoclomazone mostly against S plants. Paraquat was more toxic in S than in R plants., Conclusion: Cross-resistance to clomazone explains failures to control R plants in rice fields, and safening by P450 inhibitors suggests that oxidative activation of clomazone is needed for toxicity to E. phyllopogon. Clomazone resistance requires mitigation of 5-ketoclomazone toxicity, but P450 detoxification may not significantly confer resistance, as P450 inhibitors poorly synergized 5-ketoclopmazone in R plants. Responses to paraquat suggest research on mechanisms to mitigate photooxidation in R and S plants is needed.