EFFECTS OF COPPER-ENRICHED COMPOSTS APPLIED TO COPPER-DEFICIENT SOIL ON THE YIELD AND COPPER AND ZINC UPTAKE OF WHEAT

A pot experiment and a field experiment were conducted to investigate Cu-enriched composts made from Elsholtzia splendens plants as basal fertilizers to correct Cu deficiency in winter wheat (Triticum aestivum L.) grown in Cu-deficient soils. An application of the compost significantly increased plant height, biomass, grain yield, and 1000-grain weight. In the pot experiment, plant height and shoot biomass in the 2% Cu-rich compost treatment increased 0.8- and 5.2-fold compared with the chemical fertilizer treatment at the mature stage. Compared to chemical fertilizer control, the 2% Cu-enriched compost addition increased grain yield per pot by about 9.5-fold and 1000-grain weight by about 50%. In the field study, the compost also showed stimulatory effects on plant growth and grain yield. The results indicate that composting E. splendens plants grown in a Cu-contaminated soil and then applying the compost to a Cu-deficient soil may be an effective technique for the remediation of contaminated soils and redistribution of the copper as a plant nutrient for copper-deficient soils.     

THE EFFECT OF TEMPERATURE AND HUMIDITY ON THE RATE OF DEVELOPMENT AND MORTALITY OF TRIBOLIUM CASTANEUM (HERBST) (COLEOPTERA, TENEBRIONIDAE)

The speed of development and the developmental mortality of Tribolium castaneum were studied over a series of temperatures between 15 and 40°C. at 10, 30, 70 and 90% R.H. using wheatfeed as food.
Eggs did not hatch at any humidity at 17·5°C. or less, nor at 10% R.H. at 40°C. At all other conditions about 80% of eggs hatched. Humidity does not affect the duration of the egg period. The effect of temperature on the egg period is shown graphically, the shortest period occurring at 37·5°C.
Larvae fail to develop into normal adults at 20°C. and also fail at 90 and 30% R.H. at 40°C. At 20°C. and 70% R.H. pupae may be formed but they do not become normal adults. The rate of larval development is affected by both temperature and humidity. Development is quickest at the highest humidity used at any temperature and at 35°C. for each humidity. Larval mortality is less than 20% except at 40°C. and at combinations of low humidity and low temperature. The results correspond with published results using similar foodstuffs.
Groundnuts were used as a food in a series of experiments at 30°C. and another series at 70% R.H. Larvae on this food were much more susceptible to the effects of humidity and were unable to develop at 20 or 40°C. at 70% R.H. In all conditions development was slower and mortality higher than on wheatfeed.
The pupal period is not affected by humidity and is shortest at 37·5°C.
The conditions in which Park found that cultures of T. castaneum became extinct, 24°C. and 30% R.H., lie inside the zone in which development is possible. The possible causes for this discrepancy are discussed.     

THE INFLUENCE OF DISSOLVED-OXYGEN CONCENTRATION ON THE TOXICITY OF UN-IONIZED AMMONIA TO RAINBOW TROUT (SALMO GAIRDNERII RICHARDSON)

Periods of survival of rainbow trout in concentrations of un-ionized ammonia in the range 0.86-1.96 parts per million of nitrogen increased as the concentration of dissolved oxygen was raised from 1–5 to 8-5 p.p.m.
At each concentration of dissolved oxygen the period of survival decreased as the concentration of un-ionized ammonia increased from 0.86 to 1.96 p.p.m.
The effect of oxygen in increasing survival time was greater in the lower concentrations of un-ionized ammonia.     

THE EFFECTS OF TEMPERATURE AND HUMIDITY ON THE RATE OF DEVELOPMENT AND THE MORTALITY OF TRIBOLIUM CONFUSUM DUVAL (COLEOPTERA, TENEBRIONIDAE)

The speed of development and the developmental mortality of Tribolium confusum were studied over a series of constant temperatures between 15° and 40° C. at 10, 30, 70 and 90% R.H. using wheatfeed as food.
Eggs did not hatch at 15° or 40° C. at any humidity. At 37.5° C. about 60% of eggs hatched and at all other conditions about 90% hatched. The effect of temperature on the duration of the egg period is shown graphically, the shortest period being at 35° C. Humidity does not affect the egg period.
Larvae failed to develop to pupae at 17.5° C., at 10% R.H. at 20° C, and at 10 and 90% R.H. at 37.5° C. The rate of larval development was affected by both temperature and humidity being quickest at the higher humidities and at about 32.5° C. Larval mortality was less than 16% except at 37.5° C., at 10% R.H. or less, and at 20°C., 90% R.H.
The duration of the pupal period was not affected by humidity and was shortest at 37.5°C. The total developmental period is compared with that of T. castaneum over the range of temperature and humidity conditions in which both species can grow. The optimum for developmental speed and the maximum and the minimum temperatures at which development is possible were all about 2.5°C. lower for T. confusum than for T. castaneum. The developmental periods for the two species were equal at temperatures between 23 and 27°C., depending on humidity. At lower temperatures, T. confusum developed the more quickly and at higher temperatures the more slowly.     

THE TOXICITY OF DDT IN ABRASIVE AND NON-ABRASIVE DUSTS TO THE RICE WEEVIL, CALANDRA ORYZAE L. (COLEOPT., CURCULIONIDAE)*

The toxicity of DDT in different dust carriers to the rice weevil, Calandra oryzae , was determined under standardized conditions, using deposits large enough to ensure that the insects accumulated an excess of dust.
Some evidence was obtained that DDT is transported to the cuticle as a vapour.
At high humidity, the toxicity of DDT was not markedly affected by any carrier except charcoal which reduced the toxicity, probably by absorption of DDT vapour. Small differences in toxicity of DDT caused by other carriers could not be accounted for by differences in their average particle size, bulk density, amount adhering to insect, surface area, abrasiveness to insects or effect on behaviour of the insect.
At low humidity, abrasive dusts killed the insects by desiccation, thus adding to the toxic effect of DDT. Abrasion of the insect's cuticle did not affect the apparent rate of penetration of DDT at 50% R. H. or at 95% R. H.
Starved insects were more susceptible to DDT poisoning, and in some experiments abrasive carriers increased the toxicity of DDT by preventing the insects from feeding.