No abstract

SUMMARYVariation for K" and Na^ accumulation at low salinities in hydroponic (water) culture were observed in shoots of different wheat species. Greater discrimination (in favour of K+ and against Na+ accumulation) was shown by hexaploid bread wheat {Triticum aestivum L.) than by tetraploid durum wheat (T. turgidum L.). Since Aegilops tauschii Cosson {A. squarrosa L.), the source of the D genome in bread wheat, also exhibited high discrimination between K"^ and Na^, it was concluded that the character resided in the D genome. Studies of aneuploid bread wheat lines and disomic substitution lines of D genome chromosomes for their A and B genome homoeologues in durum wheat cv. Langdon revealed that the trait was controlled by the long arm of chromosome 4D. Since the aneuploid and disomic substitution lines showed better relative salt tolerance than durum wheat, but had lower yield potentials, we recombined chromosome 4D with chromosome 4B in a tetraploid wheat background using a homoeologous pairing mutant. This produced families of 4D/4B recombinant lines, some of which exhibited the enhanced K'^/Na'^ discrimination trait. RFLP analysis confirmed that the trait was controlled by a single gene (Knal) which was completely linked to five markers on the distal third of the long arm of 4D. A second cycle of homoeologous recombination was employed to remove the distal 4D genetic material from the recombined Knal 4B/4D chromosome and to map Kfial in greater detail. By this strategy, Knal was mapped within a short 2 cM region. Genetic analysis of K"^: Na"^ ratios showed very high LOD scores in this region for plants grown in solution culture, but lower values for plants grown in the field.In general, recombinant lines which exhibited the enhanced K+/Na+ trait were slightly more tolerant of salinity in the field and in sand culture than recombinants lacking the trait. There was, however, considerable variation between individual lines. Ion discrimination and relative tolerance were also higher in a Knal recombinant (line no. R3) than in a knal recombinant (line no. R165) in sodic conditions. In these two lines the enhanced K+/Na+ discrimination trait did not alter responses to low potassium or calcium supply.

The optimum Ca 2+ concentration for growth of cotton (Gossypium hirsutum cv. Acala S J-2) was in the range 1 to 15 mol m -3 for plants growing in hydroponic culture with 100-150 mol m -3 NaC1. Most saline (but not sodic) soils contain higher Ca 2+ concentrations. CaC12 was inhibitory to the growth of cotton above 20-50 mol m -3. Increasing concentrations of Ca 2+ in the range 0-2 mol m -2 drastically reduced Na + accumulation in the leaves. As CaC12 concentrations were increased above the optimum for growth there was a further reduction in leaf Na + accumulation, but this was more than offset by increased leaf Ca 2+ and C1 concentrations. Leaf K + concentrations were not much affected by changes in external CaCI2 concentrations. The response of Mg 2+ varied from an increase to a decrease with increasing external CaC12 and was influenced by nutritional status. There was no evidence that high Ca 2+ caused a deficiency of Mg 2÷ in cotton. Except for CI-, whose concentrations tended to decrease initially and then increase as the CaC12 concentration increased, the anions were largely unaffected by changes in external CaC12.

Project financing" refers to those financings whose source of repayment is limited to the revenue stream generated by a particular development.Companies use project financing to (1) raise capital, (2) reduce financial exposure, and (3) reduce capital costs.Project loans can be broken down into three categories based on degree of parent company support.They are (l) total guaranty, (2) project facilities completion guaranty, and (3) limited guaranty.Project financing can be designed to meet a company's exact needs and requirements at a lower over-all financing cost to the company.

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