The absolute and relative growth of the liver, kidney, heart and lung-and-trachea were studied for 64 female, 64 castrated male and 64 intact male indigenous Nigerian pigs between birth and 672 days of age. Highly significant (P < 0·001) sex and age influences were obtained for the absolute and relative weights of the liver, kidney and heart. At 280 days of age, the four organs on average weighed 28 times their birth values; the terminal weights averaged 1·31 times their values at 280 days. Organ growth became stabilized after 280 days.

The allometric equation: Y = aXb, transformed to its linear form log Y = log a + b log X, was employed to examine the relationship between organ weight and body weight. The growth coefficients 6 obtained ranged from 0·787 for kidney to 0·850 for lung-and-trachea and were similar to values reported in the literature. The accompanying highly significant R2 values strongly indicate that the functions of these organs are related to overall metabolism, which in turn is strongly dependent on body size.

A field trial was conducted during 1982–3 and 1983–4 on a loamy sand soil to study the effect of magnesium application to the soil and in foliar spray in relation to various levels of nitrogen on the growth and yield of wheat. Results indicate that wheat responde significantly to magnesium application only at the higher level of nitrogen. At the higher level of N (120 kg/ha), the response of wheat to magnesium application (10 kg/ha) to the soil and in foliar spray was 56 and 68 kg grain/kg Mg, respectively. However, the corresponding values at a low level of N (60 kg/ha) were only 14 and 15 kg grain/kg Mg. Magnesium at the higher level of N increased the chlorophyll content of leaves, leaf area index, interception of photosynthetically active radiation, number of ear-bearing tillers and number of grains per ear. The higher level of magnesium (20 kg/ha) did not result in extra beneficial effect compared with the lower level of Mg (10 kg/ha). Maximum interception of photosynthetically active radiation by the wheat canopy coincided with the attainment of maximum leaf area index and chlorophyll content of leaves at 90 days after sowing.

Potato (Solanum tuberosum L.) is propagated vegetatively using the tuber because it rarely survives from the true seed. Under normal conditions, potatoes left in the air or dry soil will produce sprouts but not roots. Large and vigorous sprouts are indicators of rapid emergence and relatively early maturity.

Morrison et al. (1972), Hsia, Fuller & Koh (1974), and Ho & Khoo (1977) showed that sprinkling can alleviate the adverse effects (Straub et al. 1976) of high ambient temperature on feed intake and growth of pigs. Vajrabukka, Thwaites & Farrell (1986) demonstrated that pigs need to be thoroughly wet by sprinkling at least once every 60 min if high evaporative rates are to be maintained, but little is known of the relative benefits of different sprinkling regimes for pigs growing at high temperatures.

It is estimated that only 35–50% of the potential yield of field lettuce crops is harvested (Gray, 1978c). A major contributory factor is the failure to establish full, uniform plant stands. Erratic lettuce emergence has been attributed to inadequate soil moisture, soil crusting, and high (> 25 °C) soil temperature (Hemphill, 1982).