Mineral Nutrient Assimilation Research Articles

Calcium in the mineral nutrition of yellow passion fruit cultivated in lined pits and with saline water

ABSTRACT Nutritional status is an important tool in salinity management, because salt stress interferes with both the absorption and the assimilation of mineral nutrients by plants. The objectives of this experiment were to evaluate the effects of water salinity, lateral protection of pits against water losses and calcium doses on the leaf concentration of macronutrients and sodium of yellow passion fruit cv. BRS GA1. The treatments were arranged in a randomized block design in split plots in a 2 × (2 × 5) factorial scheme, corresponding to water salinity (0.3 and 4.0 dS m-1) in the main plot, and the combinations between lateral protection of pits (without and with) and calcium doses (0, 30, 60, 90 and 120 kg ha-1) in the subplots. Leaf concentrations of macronutrients and sodium were determined at the phenological stage of full flowering. Irrigation of yellow passion fruit with 4.0 dS m-1 water decreased the leaf concentrations of macronutrients. The lining of the pits compromised macronutrient concentration in the plants. Calcium fertilization is recommended for yellow passion fruit cultivated in Entisol with low calcium concentration at the dose of 60 kg ha-1, because it raises nitrogen and calcium concentrations in plants irrigated with non-saline water and magnesium and sulfur concentrations in those irrigated with saline water. Calcium attenuates salt stress because it promotes the accumulation of macronutrients in yellow passion fruit under saline conditions.

Nitrogen Starvation Differentially Influences Transcriptional and Uptake Rate Profiles in Roots of Two Maize Inbred Lines with Different NUE.

Nitrogen use efficiency (NUE) of crops is estimated to be less than 50%, with a strong impact on environment and economy. Genotype-dependent ability to cope with N shortage has been only partially explored in maize and, in this context, the comparison of molecular responses of lines with different NUE is of particular interest in order to dissect the key elements underlying NUE. Changes in root transcriptome and NH4+/NO3− uptake rates during growth (after 1 and 4 days) without N were studied in high (Lo5) and low (T250) NUE maize inbred lines. Results suggests that only a small set of transcripts were commonly modulated in both lines in response to N starvation. However, in both lines, transcripts linked to anthocyanin biosynthesis and lateral root formation were positively affected. On the contrary, those involved in root elongation were downregulated. The main differences between the two lines reside in the ability to modulate the transcripts involved in the transport, distribution and assimilation of mineral nutrients. With regard to N mineral forms, only the Lo5 line responded to N starvation by increasing the NH4+ fluxes as supported by the upregulation of a transcript putatively involved in its transport.

Influence of NaCl Salinity and Different Substracts on Plant Growth, Mineral Nutrient Assimilation and Fruit Yield of Strawberry

A hydroponic culture was carried out with strawberry cv. Camarosa to investigate the effects of four salinity levels and four different substrates on plant growth, mineral nutrient assimilation and fruit yield of strawberry. Total dry weight accumulation of plants was not inhibited at low salinities, but it was significantly inhibited at 60 mM NaCl. Dry mass (DM) partitioning in NaCl-stressed plants was in favor of crown and petioles and at the expense of root, stem and leaf, whereas leaf, stem and root DM progressively declined with an increase in salinity. Specific leaf area (SLA) and leaf area ratio (LAR) significantly decreased in cv. Camarosa at 60 and 90 mM. Results also showed that the presence of NaCl in the root medium induced an increase in total Na+ content of the plants in the shoot and root. Despite Na+ and K+, the increase in total inorganic ions resulted from increasing salinity, with Ca2+ and Mg2+ concentrations decreasing in shoot and increasing in roots with an increase in salinity. For all micro- and macroelements however, significant concentration changes related to different substrates were not detected in the present experiments. Results also showed a significant decline of Fe content of 40% and 49% in shoot and root, respectively.

Impacts of NaCl stress on plant growth and mineral nutrient assimilation in two cultivars of strawberry

Two strawberry ( Fragaria × ananassa Duch.) cvs Korona and Elsanta differing in their tolerance to NaCl salinity were exposed to 40 and 80 mmol NaCl L −1 for over 4 months in the growing seasons of 2002 and 2003, respectively. However, the osmotic potential, i.e. the NaCl concentration of the root medium, varied during the experiments, because Hoagland solution and demineralized water were added usually once a week in order to push NaCl uptake on the one hand, but to allow leaching the soil after application of demineralized water on the other. Leaching the soil should quickly improve the water relations of the plant, but not affect salt levels within the plant. This strategy was chosen to reduce the effects of water stress and to focus onto the salt-specific impacts of NaCl stress. The salt stress reduced fresh and dry matter of the whole plants and photosynthetically active leaf area, especially in cv. Elsanta. Typical leaf symptoms of Na and Cl stress were detected in both cvs and the combined effects of both toxic ions resulted in the leaf scorching symptoms. Na uptake of both cvs was similar, but distribution of Na within plants was different. Korona was able to protect leaves more efficiently from Na accumulation. Under NaCl stress Korona plants achieved a significant increase of K content in leaves and crowns, while Elsanta showed an increase of K in fruits and petioles. The accumulation of K under evaluated NaCl levels suggests an efficient K uptake system in strawberry plants. Concentrations of Ca were not significantly affected, with the exception of rising levels in roots of Elsanta plants. Concentrations of Mg, Mn and Fe significantly decreased in leaves, while those of Mg and Mn remarkably rose in crowns of both cvs. N content in leaves, petioles, and roots of both cvs increased. In addition it rose in fruits and crowns in cv. Elsanta. A significant limitation of N uptake by competition with Cl did not occur in these plants. Concentrations of P increased in roots and petioles of both cvs, and in fruits of cv. Elsanta. With respect to Zn and Cu, significant concentration changes related to NaCl stress could not be detected.

Reviews

R. Adams Dutcherand Dennis E. Haley, Agricultural Biochemistry. New York: John Wiley & Sons, 1932. Pp. x+484. $4.50.This book is the outgrowth of lectures presented to agricultural students over a period of nearly twenty years and is designed for the use of students who have had preliminary training in inorganic and organic chemistry. Part I deals with the development of agricultural chemistry, the chemistry of living matter, and the physical state of matter. It also contains chapters on the chemistry of the carbohydrates, the fats, the proteins and enzymes. Plant chemistry is the subject of Part II, special emphasis being given to seed germination, the soil, fertilizers, the synthesis of plant carbohydrates, lipids and proteins, and the absorption and assimilation of mineral nutrients. Part III deals with animal nutrition. Topics of particular importance are the body tissues, including metabolic changes, the digestion of foods, energy metabolism, protein quality, .