Studies of Fruit Development in Relation to Plant Hormones: IV. Acidic Auxins and Growth Inhibitors in Leaves and Fruits of the Apple

Apple leaves and fruits are shown to contain three acidic growth-promoting and two acidic growth-inhibiting substances which appear to be different from any chemically known auxins or growth-inhibitors. By means of the technique of paper chromatography the distribution of these substances in fruits and seeds at different stages of development has been investigated. On the basis of the results so far obtained the possible significance of certain of these substances in fruit development is discussed.     

Growth Regulator Effects on Quality and Pre-Harvest Drop of Worcester Pearmain Apples

The application of 2-chloroethylphosphonic acid (CEPA) at 750 or 1500 ppm improved the colour of early harvested Worcester Pearmain apples but greatly increased pre-harvest drop. The drop-promoting effect of CEPA could be overcome by applying succinic acid 2,2-dimethyl hydrazide (aminozide) at 2000 ppm or a-(2,4,5-trichlorophenoxy)-propionic acid (2,4,5-TP) at 20 ppm. The combination of CEPA 750 ppm+2,4,5-TP 20 ppm appeared to be particularly promising for improving the attractiveness, flavour and texture of Worcester Pearmain picked on 1st September and 7th September. No damage was seen on the trees either in the year of application or the following year.     

The emergence and early growth of French and runner beans (Phaseolus vulgaris L. and Phaseolus coccineus h.) sown on different dates

The results are reported of an investigation into the effects of sowing on different dates on the emergence and growth of various cultivars of Phaseolus vulgaris and P. coccineus under field conditions. In 1969 five cultivars of French bean and three of runner bean were sown in the field at fortnightly intervals from April onwards. The experiment was repeated, with the addition of two cultivars, in 1970. Consistent differences were found between and within species for a number of growth parameters.

(1) Especially in the early sowings, seedlings of runner beans emerged before those of French beans, and small-seeded cultivars of French bean (in particular Comtesse de Chambord) before larger-seeded cultivars.

(2) The mean relative growth rates measured after emergence were greater in French beans than in runner beans, but differences within species were not significant. Very early sowing appeared to have a lasting depressive effect on the growth rates of seedlings of both species.

(3) The estimated weights of seedlings at emergence (estimated from regressions of seedling weight on time since emergence and on seed weight) were lower in the early sowings than in later sowings, and especially so in the cultivar Comtesse de Chambord.

The main results in each year were similar, but some differences in detail were found. In particular there were differences between years in the emergence of cultivars as affected by soil temperature. The discrepancies were attributed to a difference in the temperature regimes of the two sites.     

Improved seed development and germination of stenospermic grapes by plant growth regulators

Plant growth regulators were applied to the foliage and immature fruit clusters of the stenospermic grape selection ‘C35-33’ at various periods before bloom to stimulate viable seed development. In the 1987 season five different plant growth regulators were used, but in 1988 the growth retardants Cycocel and XE-1019 were used exclusively. Chemical treatments applied 35 days after bud break increased significantly germination percentage. Experimental results indicate that the use of certain plant growth regulators may aid in increasing the efficiency of seedless grape breeding by providing an alternative to in-ovulo embryo culture.     

The effects of mechanically-induced stress and water stress on freezing resistance in lettuce and cauliflower seedlings

Summary

Mechanically-induced stress, applied by brushing young lettuce and cauliflower plants for 90 s each day, reduced the freezing resistance of cauliflower but had no effect on that of lettuce. Brushing reduced fresh weight in both species and smaller plants were less freezing-resistant than larger ones. The levels of abscisic acid (ABA) in the shoots of brushed cauliflowers were slightly less than in unbrushed plants, whereas in lettuce the levels were similar in the two treatments. ABA sprayed onto lettuce plants had no effect on freezing resistance. With both lettuce and cauliflower, freezing resistance, and the osmolarity of sap extracted from the shoots, increased following water-stress and declined progressively following rehydration.     

Distribution and Phytoavailability of Lead in a Soil Contaminated with Lead Shot

Water, Air, &; Soil Pollution - This paper presents a study of Pb contamination of soil at a clay target shooting facility in Canterbury, New Zealand. The spatial distribution of Pb...     

The effect of phosphorus supplementation to common carp diets on fish growth

The effect of supplementation of fish diets with phosphorus was studied both in tank and pond experiments. In the tank experiments phosphorus (6.5% di-calcium or mono-calcium phosphates) was added to three diets: two containing fish meal as the main protein ingredient and the third containing algal meal to replace it. Feeding common carp in tanks with these diets significantly increased fish growth rate (P < 0.05) over fish fed the same diets without phosphorus supplementation. In the pond experiments phosphorus was added to a fish meal diet in two different compounds: mono- and di-calcium phosphates (at 1% of the feed). The diets were fed to fish in a polyculture system for two consecutive culture cycles. Due to supplementation with phosphate, growth rate of tilapia (Sarotherodon aureus) increased in both culture cycles. The growth rate of common carp fed phosphorus-supplemented diets increased over the control only in the first cycle, when fish were large and the standing crop of carp exceeded 1.8 ton/ha. At lower standing crops the natural food seems to supply adequate amounts of phosphorus. Silver carp were not affected by phosphorus supplementation, probably because they consume very little supplementary feed. Total yield for the entire season (kg/ha) was significantly higher in ponds where fish were fed a phosphorus-supplemented diet. Di-calcium phosphate, which is soluble only in weak acids, seems to be more efficient than the water-soluble mono-calcium phosphate in affecting the growth of common carp even though this fish lacks a gastric acid secretion.     

Median Lethal Concentration (LC50) of Piscicidal Plants and Their Utilization in Aquaculture

Aqueous and ethanol extracts of Acacia pennata (bark), Catunaregam uliginosa (fruit), Diospyros lenceofolia (fruit), and Sapindus mukorossi (fruit) were evaluated as piscicides on the freshwater fish Danio dangila, Danio rerio, and Puntius shalynius, and the air-breathing Heteropneustes fossilis. Catunaregam uliginosa (fruit) possessed relatively higher piscicidal potency followed by Sapindus mukorossi (fruit), Acacia pennata (bark), and lastly Diospyros lanceofolia (fruit). Catunaregam uliginosa can thus be used for eradicating unwanted wild fishes in a short time span at low concentrations so that the health of aquatic environment is maintained.