1. Plant Nutrients. 2. The Soil as a Plant Nutrient Medium. 3. Nutrient Uptake and Assimilation. 4. Plant Water Relationships. 5. Plant Growth and Crop Production. 6. Fertilizer Application. 7. Nitrogen. 8. Sulphur. 9. Phosphorus. 10. Potassium. 11. Calcium. 12. Magnesium. 13. Iron. 14. Manganese. 15. Zinc. 16. Copper. 17. Molybdenum. 18. Boron. 19. Further Elements of Importance. 20. Elements with More Toxic Effects. General Readings. References. Index.

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Principles of plant nutrition

▪ Abstract Rhamnogalacturonan II (RG-II) is a structurally complex pectic polysaccharide that was first identified in 1978 as a quantitatively minor component of suspension-cultured sycamore cell walls. Subsequent studies have shown that RG-II is present in the primary walls of angiosperms, gymnosperms, lycophytes, and pteridophytes and that its glycosyl sequence is conserved in all vascular plants examined to date. This is remarkable because RG-II is composed of at least 12 different glycosyl residues linked together by more than 20 different glycosidic linkages. However, only a few of the genes and proteins required for RG-II biosynthesis have been identified. The demonstration that RG-II exists in primary walls as a dimer that is covalently cross-linked by a borate diester was a major advance in our understanding of the structure and function of this pectic polysaccharide. Dimer formation results in the cross-linking of the two homogalacturonan chains upon which the RG-II molecules are constructed and ...

RHAMNOGALACTURONAN II: Structure and Function of a Borate Cross-Linked Cell Wall Pectic Polysaccharide

▪ Abstract New and exciting developments in boron research in the past few years greatly contributed to better understanding of the role of boron in plants. Purification and identification of the first boron-polyol transport molecules resolved much of the controversy about boron phloem mobility. Isolation and characterization of the boron-polysaccharide complex from cell walls provided the first direct evidence for boron crosslinking of pectin polymers. Inhibition and recovery of proton release upon boron withdrawal and restitution in plant culture medium demonstrated boron involvement in membrane processes. Rapid boron-induced changes in membrane function could be attributed to boron-complexing membrane constituents. Boron may affect metabolic pathways by binding apoplastic proteins to cis-hydroxyl groups of cell walls and membranes, and by interfering with manganese-dependent enzymatic reactions. In addition, boron has been implicated in counteracting toxic effects of aluminum on root growth of dicotyle...

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Boron in plant structure and function

The essential micronutrients for field crops are B, Cu, Fe, Mn, Mo, and Zn. Other mineral nutrients at low concentrations considered essential to growth of some plants are Ni and Co. The incidence of micronutrient deficiencies in crops has increased markedly in recent years due to intensive cropping, loss of top soil by erosion, losses of micronutrients through leaching, liming of acid soils, decreased proportions of farmyard manure compared to chemical fertilizers, increased purity of chemical fertilizers, and use of marginal lands for crop production. Micronutrient deficiency problems are also aggravated by the high demand of modern crop cultivars. Increases in crop yields from application of micronutrients have been reported in many parts of the world. Factors such as pH, redox potential, biological activity, SOM, cation-exchange capacity, and clay contents are important in determining the availability of micronutrients in soils. Plant factors such as root and root hair morphology (length, density, surface area), root-induced changes (secretion of H + , OH − , HCO 3 − ), root exudation of organic acids (citric, malic, tartaric, oxalic, phenolic), sugars, and nonproteinogenic amino acids (phytosiderophores), secretion of enzymes (phosphatases), plant demand, plant species/cultivars, and microbial associations (enhanced CO 2 production, rhizobia, mycorrhizae, rhizobacteria) have profound influences on plant ability to absorb and utilize micronutrients from soil. The objectives of this article are to report advances in research on the micronutrient availability and requirements for crops, in correcting deficiencies and toxicities in soils and plants, and in increasing the ability of plants to acquire needed amounts of micronutrient elements.

Micronutrients in Crop Production

Interest in plant asparagine has rapidly taken off over the past 5 years following the report that acrylamide, a neurotoxin and potential carcinogen, is present in cooked foods, particularly carbohydrate-rich foods such as wheat and potatoes which are subjected to roasting, baking or frying at high temperatures. Subsequent studies showed that acrylamide could be formed in foods by the thermal degradation of free asparagine in the presence of sugars in the Maillard reaction. In this article, our current knowledge of asparagine in plants and in particular its occurrence in cereal seeds and potatoes is reviewed and discussed in relation to acrylamide formation. There is now clear evidence that soluble asparagine accumulates in most if not all plant organs during periods of low rates of protein synthesis and a plentiful supply of reduced nitrogen. The accumulation of asparagine occurs during normal physiological processes such as seed germination and nitrogen transport. However, in addition, stress-induced asparagine accumulation can be caused by mineral deficiencies, drought, salt, toxic metals and pathogen attack. The properties and gene regulation of the enzymes involved in asparagine synthesis and breakdown in plants are discussed in detail.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1744-7348.2006.00104.x

Asparagine in plants

TERMINAL FLOWER is a key regulator of floral timing in Arabidopsis and other herbaceous species. A homolog of this gene, CsTFL, was isolated from the hybrid perennial tree crop Washington navel orange (Citrus sinensis L. Osbeck). The deduced amino acid sequence of CsTFL was 65% identical to the Arabidopsis TFL1 protein. Wild-type Arabidopsis plants ectopically expressing CsTFL showed late-flowering phenotypes similar to those described for overexpression of Arabidopsis TFL1. In addition, the 35S:CsTFL transgene complemented the tfl1-2 mutant. The severity of the overexpression phenotypes correlated with the amount of CsTFL transcript that accumulated. Unlike many model systems that have been studied, C. sinensis maintains two distinguishable CsTFL alleles. CsTFL transcripts from either allele were not detected in adult vegetative tissues using reverse transcription-PCR, but CsTFL RNAs were detected in all floral organs. In addition, real-time PCR determined that juvenility in citrus was positively correlated with CsTFL transcript accumulation and negatively correlated with the floral-regulatory genes, LEAFY and APETALA1, RNA levels.

http://www.plantphysiol.org/content/plantphysiol/135/3/1540.full.pdf

Isolation and Characterization of a TERMINAL FLOWER Homolog and Its Correlation with Juvenility in Citrus

Phaseolus acutifolius A. Gray is a potential source of stress-tolerant traits for Phaseolus vulgaris L. through interspecific hybrids. The objective of this study was to quantify the effects of water-deficit stress on vegetative growth, shoot relative water content (RWC), and leaf concentrations of proline, polyamines, and related metabolites in P. vulgaris compared with P. acutifolius. Stress-induced changes in N metabolism putatively related to stress tolerance have not been investigated previously in P. acutifolius. Replicate pots, each containing three 5-d-old plants in 18.9 L of soil with 4 L of available water, were subjected to water deficit by withholding water (terminal drought) or were maintained under well-watered (control) conditions. Compared with controls, stressed plants of both species accumulated approximately 55% less shoot dry matter. Root dry matter accumulation was inhibited to a greater degree in P. acutifolius (70% for two genotypes) than in P. vulgaris (14 and 27% for two genotypes). P. acutifolius maintained greater shoot RWC than P. vulgaris. In droughted plants of P. acutifolius, leaf arginine and proline concentrations did not change, total polyamine (Σ agmatine + putrescine + spermidine + spermine) concentrations decreased, and ammonia increased compared with controls. In P. vulgaris, water deficit increased concentrations of arginine (>30%) and proline (>300%), whereas total polyamine and ammonia concentrations did not change compared with controls. In all four genotypes examined, proline concentration was inversely related to RWC (R 2 ≥ 0.90). Leaf proline concentration is an indicator of plant water status in Phaseolus but not of tolerance or sensitivity of vegetative growth to water deficit.

Relationship between Relative Water Content, Nitrogen Pools, and Growth of Phaseolus vulgaris L. and P. acutifolius A. Gray during Water Deficit

The accumulation of arginine in leaves of four citrus rootstock cultivars during P deficiency has been demonstrated to be due to increased de novo synthesis rather than decreased catabolism or increased protein degradation (E Rabe, CJ Lovatt, 1984, Plant Physiol 76: 747-752) In this report, we provide evidence (a) that the increased activity of the arginine biosynthetic pathway observed for citrus rootstocks grown under P-deficient conditions for 7 months is due to an increase in the concentration of ammonia in leaves of P-deficient plants and (b) that ammonia accumulation and removal through arginine systhesis are early responses to phosphorus deficiency for both a woody perennial, rough lemon ( Citrus limon ), and an herbaceous annual, summer squash ( Cucurbita pepo ) Transferring 5-day-old squash plants to a phosphorus-deficient nutrient solution for only 10 days resulted in a 2-fold increase in the concentration of nitrate in the youngest fully expanded leaves (YFE) Concomitantly, the specific activity of nitrate reductase doubled and the ammonia content of P-deficient YFE leaves increased to a concentration significantly greater that of leaves from healthy control plants (P 14 CO 3 into arginine plus urea doubled during phosphorus deficiency and arginine accumulated Despite the accumulation of nitrate and ammonia in YFE leaves during phosphorus deficiency, the total nitrogen content of these leaves was less than that of the healthy control plants Similar results were obtained for rough lemon Nitrate content of the YFE leaves increased 15- and 30-fold in plants deprived of phosphorus for 6 and 12 weeks, respectively Ammonia content of the leaves increased as P deficiency progressed to 14 ± 008 mg (± se, n = 4) per gram dry weight, a level 18-fold greater than that of the P-sufficient control plants During P deficiency de novo arginine biosynthesis in rough lemon increased 10-fold Immersing the petiole of YFE leaves from P-sufficient squash and rough lemon plants in 50 millimolar NH 4 + for 3 hours resulted in the accumulation of ammonia in the leaves, and a 4-fold increase in the incorporation of NaH 14 CO 3 into arginine plus urea Taken together, these results provide strong evidence that the accumulation of nitrate and ammonia in leaves is an early response of both woody and herbaceous plants to P deprivation The data are consistent with the hypothesis that increased de novo arginine biosynthesis in leaves during P deficiency is in response to ammonia content of the leaves

http://www.plantphysiol.org/content/plantphysiol/81/3/774.full.pdf

Increased Arginine Biosynthesis during Phosphorus Deficiency : A Response to the Increased Ammonia Content of Leaves

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Isolation and Characterization of LEAFY and APETALA1 Homologues from Citrus sinensis L. Osbeck `Washington'

Inflorescence and flower development of the 'Hass' avocado (Persea americana Mill.) were investigated at the macro- and microscopic level with three objectives: (1) to determine the time of transition from vegetative to reproductive growth; (2) to develop a visual scale correlating external inflorescence and flower development with the time and pattern of organogenesis; and (3) to quantify the effect of high ("on") and low ("off") yields on the flowering process. Apical buds (or expanding inflorescences) borne on summer shoots were collected weekly from July to August during an "on" and "off" crop year. Collected samples were externally described and microscopically analyzed. The transition from vegetative to reproductive condition probably occurred from the end of July through August (end of shoot expansion). During this transition the primary axis meristem changed shape from convex to flat to convex. These events were followed by the initiation of additional bracts and their associated secondary axis inflorescence meristems. A period of dormancy was not a prerequisite for inflorescence development. Continued production of secondary axis inflorescence meristems was observed from August to October, followed by anthesis seven months later. In all, eleven visual stages of bud development were distinguished and correlated with organogenesis to create a scale that can be used to predict specific stages of inflorescence and flower development. Inflorescence development was correlated with minimum temperature less than or equal to 15 degrees C, whereas yield had little effect on the timing of developmental events of individual inflorescence buds. However, the high yield of the "on" year reduced inflorescence number and increased the number of vegetative shoots. No determinate inflorescences were produced during the "on" year. For the "off" year, 3% and 42% of shoots produced determinate and indeterminate inflorescences, respectively

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Carol J. Lovatt

Papers

Isolation and Characterization of a TERMINAL FLOWER Homolog and Its Correlation with Juvenility in Citrus

Relationship between Relative Water Content, Nitrogen Pools, and Growth of Phaseolus vulgaris L. and P. acutifolius A. Gray during Water Deficit

Increased Arginine Biosynthesis during Phosphorus Deficiency : A Response to the Increased Ammonia Content of Leaves

Isolation and Characterization of LEAFY and APETALA1 Homologues from Citrus sinensis L. Osbeck `Washington'

Inflorescence and flower development of the 'Hass' avocado (Persea americana Mill.) during "on" and "off" crop years