In a greenhouse experiment, the growth and nutrient uptake of four varieties of orchardgrass were differentially affected by soil temperature and moisture. The yield of tops, for all varieties, was increased by a rise in soil temperature from 10°C. to 20°C. and by a rise in soil moisture from 25% to 75% of the available soil moisture capacity. The yield of roots was increased by a decrease in soil temperature from 20°C. to 10°C. when associated with the high soil moisture level. Under warm soil conditions a rise in available soil moisture generally produced similar increases in top yields for all varieties; whereas, under cool soil temperature a rise in soil moisture increased top yields in the following order: Frode > Rideau > S-143 = Chinook. Under the same moisture and temperature condition root yields were in the order of Frode > Chinook = Rideau. The influence of N fertilization on herbage yield and on N uptake was only slightly affected by soil temperature and moisture. A rise in soil temperature and soil moisture increased the uptake of soil P and decreased the effect of applied P on yield and P uptake. Under P fertilization the uptake of P by the varieties differed with environment: the order was S-143 > Frode = Rideau > Chinook at 20°C. and 75% moisture, and Frode = Rideau > S-143 = Chinook at 10°C. and 25% moisture.

The levels of nitrogen which produced the optimum growth of cacao plants were found to be 80 ppm from germination until the seedlings were four months old and then 140 ppm up to eight months from planting. Eight-month-old plants receiving 140 ppm nitrogen were still increasing in weight compared to those receiving 110 ppm or less. The levels of calcium which produced optimum growth were 10ppm at two months, 50 ppm at three months, and 75 ppm at four and eight months from seeding. When the plants were eight months old, it was found that increasing levels of nitrogen had increased the percentage of root dry weight but had had little effect on the stems. They had also increased the total plant dry weight, the leaf area, and the weight of leaf per unit area (gm.jdm.J). At eight months, increasing levels of calcium had tended to decrease the percentage weight of leaves and increase the percentage weight of stem of the total plant, while the percentage root remained unchanged. There was no interaction on dry weight of plants between the nitrogen and calcium treatments. Chemical analysis of eight-month-old plants showed that increasing levels of nitrogen in the nutrient medium had increased the concentrations of nitrogen and sodium and reduced the concentrations of potassium and molybdenum in the leaves. The higher levels of calcium in the nutrient medium increased the concentrations of calcium, iron, zinc and molybdenum and decreased the concentrations of nitrogen, manganese and sodium in the leaves. It is of interest that higher levels of nitrogen were accumulated in the leaves when the nutrient medium was deficient in calcium. Work in progress indicates that such accumulation of nitrogen may have a bearing on leaf-edge scorch when the source of nitrogen is nitrate. Successively higher levels of nitrate nitrogen in the range 14-110 ppm in the nutrient medium usually produce marked increases in the growth of cacao (Lockard, Vamathevan and Thamboo, 1959; Lout\\ 1962), while a level of 220 ppm tends to retard growth and produce characteristic symptoms ofleaf scorch reminiscent of calcium deficiency(unpublished data). These observations suggest a possible interaction between nitrogen and calcium in the growth of cacao. The response of grasses and some legumes to increasing levels of calcium has been found to vary for different varieties (Bradshaw, Lodge, Jowett, and Chadwick, 1958; Snaydon and Bradshaw, 1961; Snaydon, 1962). Levels of calcium in the nutrient medium above 20 ppm gave little increase in dry weight in most varieties. The level of calcium supplied to cacao seedlings in sand-culture is normally much higher than this. However, there is little published evidence to show what levels are optimum, above which little or no increase in growth occurs, or whether the optimum level varies with age. Olsen (1942) investigated four different species of plants and showed that as the calcium content of the medium increased, three of them (Sinapis alba, Dianthus barbatus, and Hordeum distichum) absorbed more calcium but less magnesium and potassium. Tussilago farfara differed from these three species in that the potassium content increased with increasing levels of calcium in the nutrient medium. Data on the nutrient concentrations in the leaves of plants grown in control nutrients and those deficient in nitrogen or calcium are fairly extensive (Murray, 1957; Lockardet ai, 1959; Loue, 1962; Lockard and Asomaning, 1964). There is, however, no information on nutrient concentration in the leaves of cacao plants receiving factorially applied levels of nitrogen and calcium. The data presented here are the results of an experiment designed to investigate the relationship between these two elements and their effects on the growth and nutrient content of cacao seedlings.

The mutual relation between the coffee-twig beetle, an ambrosia beetle, and the coffee plant was analysed as an example of the relation between insect and host plant. By boring passages in the twigs of the coffee plant, the beetle killed the twigs. Control was hindered by the feeding of the beetle only on a fungus, Ambrosiella xylebori Brader, which was the chief cause of death. Other plants were also infested and acted as a source of infestation for coffee plantations.The relation between beetle and coffee plant was influenced by: a scent stimulus attracting the females to the plant; a scent stimulus which caused them to remain or fly off; a flavouring influenced whether the entrance passage was bored; the completion of the entrance passage depended on the nutrient reserves of the female and on the structure of the plant tissues; the boring of the brood passage depended whether the ambrosia fungus grew and growth of the ambrosia depended on the sugar content of the plant (positive relation); the number of eggs laid depended on the growth conditions for the ambrosia. Selection of less infested varieties of coffee seemed the best means of control.

The mutual relation between the coffee-twig beetle, an ambrosia beetle, and the coffee plant was analysed as an example of the relation between insect and host plant. By boring passages in the twigs of the coffee plant, the beetle killed the twigs. Control was hindered by the feeding of the beetle only on a fungus, Ambrosiella xylebori Brader, which was the chief cause of death. Other plants were also infested and acted as a source of infestation for coffee plantations.The relation between beetle and coffee plant was influenced by: a scent stimulus attracting the females to the plant; a scent stimulus which caused them to remain or fly off; a flavouring influenced whether the entrance passage was bored; the completion of the entrance passage depended on the nutrient reserves of the female and on the structure of the plant tissues; the boring of the brood passage depended whether the ambrosia fungus grew and growth of the ambrosia depended on the sugar content of the plant (positive relation); the number of eggs laid depended on the growth conditions for the ambrosia. Selection of less infested varieties of coffee seemed the best means of control.