Plant Growth Analysis: Allometry, Growth and Interference in Orchardgrass and Timothy

A multiple regression procedure was used to evaluate allometricresponses to stand age and species population densities in monoculturesand mixtures of orchardgrass (Dactylis glomerata L., also knownas cocksfoot) and timothy (Phleum pratense L.). In each speciesthe allometry between shoot dry weight and either leaf areaor tiller number per plant was studied. Population density treatmentsaffected allometry by changing allometric exponents expressingthe ratio of relative growth rates of different plant characteristics.Allometric relationships changed as growth proceeded, and thetwo species differed in their allometric responses to treatments. Plant growth analysis, allometry, competition, Dactylis glomerata L., Phleum pratense L.     

Plant Growth Analysis: Growth and Yield Component Responses to Population Density in Forage Maize

Forage maize (Zea mays L.) was grown in monocultures at populationdensities ranging from 4·9 to 11·1 plants m^–2.Data for plant growth analysis were obtained from six harvestscarried out from 21 to 115 d after planting. Conventional plantgrowth analysis indicated that improvements in forage productivityper unit land area by high population density resulted directlyfrom increased plant presence. Reduction in dry weight per shootat high population density was associated with reduced unitleaf rate. Leaf area ratio was little affected, which may implythat competition for soil nutrients or oxygen was the chiefcause of plant interference. Yield component analysis demonstratedthe increasing importance of population density treatments asa source of variation as growth progressed. Direct relationshipsbetween variation in yield per plant and variation in two yieldcomponents, stem diameter and the inverse of leaf area ratio,were demonstrated. Both conventional plant growth analysis andyield component analysis indicated complex physiological andmorphological adjustments to species population density. Plant growth analysis, yield component analysis, Zea mays L     

The ecology of the avian brain: food-storing memory and the hippocampus

Some species of birds store food, often hoarding several hundreds of seeds over a period of just a few weeks. Field and laboratory studies have demonstrated that food-storing species have an impressive memory and an enlarged region of the brain, the hippocampal region. Lesion experiments have shown that the hippocampus is important in accurate retrieval of stored food. Taken together, these results have led to the hypothesis that the enlarged hippocampus is associated with the memory requirements of retrieving stored food. In this review, we discuss four areas of study: comparative studies of the brain, comparative studies of behaviour, developmental plasticity and seasonal changes in food storing and the hippocampus.     

The ecology of the avian brain: food-storing memory and the hippocampus

Some species of birds store food, often hoarding several hundreds of seeds over a period of just a few weeks. Field and laboratory studies have demonstrated that food-storing species have an impressive memory and an enlarged region of the brain, the hippocampal region. Lesion experiments have shown that the hippocampus is important in accurate retrieval of stored food. Taken together, these results have led to the hypothesis that the enlarged hippocampus is associated with the memory requirements of retrieving stored food. In this review, we discuss four areas of study: comparative studies of the brain, comparative studies of behaviour, developmental plasticity and seasonal changes in food storing and the hippocampus.     

Effects of beet cryptic virus infection on sugar beet in field trials

The effects of beet cryptic virus (BCV) infection on sugar beet crops were investigated in field trials in 1990. Two sugar beet breeding stock lines were screened for infection by BCV. Seed lots containing different proportions of seed infected with BCV1 & 2 were obtained by crossing the stock lines and used in field trials at five different sites. Five characteristics of the infected plants were assessed. BCV infection appeared to have no significant effects on the sugar beet crop at four locations which suffered from drought stress but significant effects were found at one site where the crop was grown on grade 1 land with good moisture retention properties. Root yield and sugar yield were reduced by up to 17% and 20%, respectively, by BCV infection.     

Plant Growth Analysis: Additive and Multiplicative Components of Growth

Three techniques used to investigate whole-plant growth areplant growth analysis, yield component analysis and demographicanalysis. Each subdivides growth into morphological or physiologicalcomponents. This paper derives several relationships which definethe contributions made by components to the performance of thewhole plant. For example, the additive contributions by differentplant parts to overall unit leaf rate may be determined. Also,for multiplicative components, the relative growth rate of yieldis the sum of the relative growth rates of yield components.The relationships developed here serve to link different approachesto growth analysis, and they are illustrated using data fromgrowth studies of bean and sunflower. Plant growth analysis, yield component analysis, demographic analysis, Phaseolus vulgaris L., Helianthus annus L.