Length Of Capsule Research Articles

POPULATION DYNAMICS OF ARABIDOPSIS THALIANA (L.) HEYNH. STRAIN ‘ESTLAND’ AT DIFFERENT DENSITIES AND NUTRIENT LEVELS

SUMMARYPopulations of Arabidopsis thaliana were established in acid‐washed sand culture from sowing densities of 1, 10, 100 and 1000 seeds/pot at three levels of mineral nutrition; undiluted, 1/10 diluted and 1/100 diluted Hoagland's solution.Mortality increased with sowing density. At the highest sowing density, mortality was greatest at the lowest and least at the intermediate level of mineral nutrition.Proportionally fewer of the surviving plants reached fruiting as sowing density increased and as the nutrient supply became more dilute.Seed output/fruiting plant was highest in low sowing density populations supplied with undiluted nutrient solution and least in high sowing density populations supplied with diluted nutrient solutions.The range of variation of mean seed output/fruiting plant was 100‐fold over the different types of population, and that of its components, capsule number/fruiting plant and number of seeds/capsule 20‐fold and 5‐fold, respectively. The range of the components of number of seeds/capsule, that is, capsule length and seeds/unit length of capsule was 21/2‐fold and 2‐fold, respectively.Number of seeds/capsule varied with developmental stage, largely because later‐produced capsules were shorter. The rate of capsule development was affected by density and nutritional stress more readily than the number of seeds/capsule at a particular developmental stage.Most capsules were borne on main stems of the plants, and an allometric relationship was demonstrated between mean seed output/fruiting plant and mean length of the main stem. Departures from this relationship are discussed and the statistical properties of the frequency distributions of main stem lengths of fruiting plants examined.Attributes of fruiting plants in nine of the twelve types of population were linearly related to the density of all surviving plants on a log/log plot, a separate line being characteristic of each nutritional level. The possibility of allometric relationships between attributes and mean plant weight and of linear log/log relationships between mean plant weight and density is discussed.Seed output was constrained by plant density in nine of the twelve types of populations and free from this constraint in two of the remaining three types. The specific area for seed outputs of individual plants to be unconstrained by available space decreases as mineral nutrition level increases.Maximum seed output/population occurred over a wider range of sowing density the higher the level of mineral nutrition. At the lowest level of mineral nutrition, seed output displayed a well‐defined optimum with sowing density, but at higher levels it rose with sowing density to reach a maximum which was subsequently maintained.Mean weight of seed harvested was similar over all sowing densities at the highest level of nutrition, but it decreased with sowing density as nutrient level decreased. This decrease in seed weight was correlated with decreasing capacity to germinate 33/4 years after harvest.

Capsule Expansion in the Hairy-Cap Moss, Polytrichum

In cultured explants of Polytrichum sporophytes, capsule expan- sion requires light. Red light is more effective in promoting expansion than white, blue, or green light of equal energy. The increase in capsule dry weight is a linear function of the length of the explant in the absence of dextrose for all lengths tested, and also in the presence of dextrose over the range 10-40 mm. In the absence of dextrose, capsule gain is a linear function of weight loss in the seta over the range in seta lengths 10-40 mm. With dextrose present, capsule gain has a nonlinear relationship to seta loss because dextrose suppresses seta loss relatively more than it enhances capsule gain, with increasing length of the explant. Polytrichum juniperinum Hedw. and P. ohioense Ren. & Card. were used in this study. Gametophytes and attached sporophytes were collected as turves during the winter and spring from Portland Arch, Indiana. All sporophytes were unexpanded, and each experiment is based on sporophytes of one age, only. The plants were freshly collected and grown in a greenhouse for a few days before each experiment, to condition them to the warmer temperature of the laboratory. At the start of an experiment, sporophytes were stripped of their calyptras and removed from the gametophytes, surface sterilized in 5% Clorox for 5 minutes, cut to length by removing the foot and a variable portion of the seta above the foot, and planted base down. Except where noted, explants were cut to 10 mm long. The length of the unexpanded capsule was estimated at 2 mm. The medium consisted of Voth's (1943) solution #5 solidified with 1% Difco Bacto Agar, with or without 1% dextrose. The explants were grown, one per 25 x 100 mm culture tube, for two weeks or longer at 23?C. Given an appropriate light regime, plants treated this way form

The Moss Genus Isotheciopsis

The Moss Genus Isotheciopsis

The pipeline flow of capsules part 6 ‐ numerical analysis of some variables determining free flow

AbstractFour specific factors, concerned with the geometry and frictional effects of a cylindrical capsule flowing freely in a liquid‐filled pipe in which the liquid is in laminar flow, have been investigated numerically. The factors are: axial displacement of the capsule from the concentric position, end configuration and length of capsule, deformed circular cross‐section and frictional effect between the bottom of the capsule and the inside pipe surface. The effect which axial displacement has on any dynamic variable, e.g. capsule velocity, was found to be a uniformly increasing one for up to 90% of the total possible displacement. Beyond 90% displacement the effect was relatively much more pronounced.Friction was found to decrease capsule velocity uniformly: as the friction force was increased a critical value was reached for larger capsules which resulted in a rapid decrease to zero. The effect of end shape on velocities and flow rates was found to be negligible, although there was a considerable change in flow pattern. Deformation of the capsule, i.e. deformation through a vertical cross‐section, caused little effect for 10–20% deformations, beyond which there was almost a linear increase of percentage deformation with pressure gradient required to maintain the same capsule velocity. The rate of increase itself increased with the proximity of the capsule to the pipe wall.

The Growth of the Head Capsule of the Japanese Beetle Larva

The fact that the width of the head capsule of an insect larva is more or less constant for any instar of a species was first demonstrated by Dyar (1890) in his study of lepidopterous larva. This characterization of an instar by head measurements has recently been extended to a large number of species belonging to many orders of insects. The Japanese beetle passes through three instars in its larval development. In the present paper, an analysis is made of a large number of measurements of both the width and the length of the head capsule of the larva at different stages of development to determine if these measurements are characteristic of each instar and can be used to separate random samples of larvae into the three instars. This separation is possible only if there is no overlapping of measurements made on larvae of successive instars.

Studies on cell number and the progression factor in the growth of Japanese beetle larvae (Popillia japonica Newman)

AbstractIncreases in weight, total body length, and width and length of the head capsule of Japanese beetle larvae were studied. Since the progression factors decreased with succeeding molts and exhibited considerable variation it was concluded that Przibram's principle is inapplicable. Cells were counted in the mid‐intestine and brain. Columnar cells of the mid‐intestine were measured. The data show: (a) No increase in cell number occurs at the time of molting. (b) The progression in weight and length cannot be correlated with an increase in cell number. In the first instar the progression for increase in weight was 5.73; while for increase in cell number, it was 1.67 for the mid‐intestine, and 1.19 for the brain. In the second instar, the corresponding figures were 5.24, 1.98 and 1.69. In the third instar average weight increased 3.18 times, but there was practically no increase in cell number. Thus, molting does not represent a definite increase in number of cells of the insect's body as suggested by Przibram and Megusar, and Bodenheimer's method of calculating cell divisions seems to have no factual basis. Increase in size of the larva is largely due to an increase in cell size. The ratio of increase in total cell volume of the columnar cells of the mid‐intestine is approximately equal to the ratio of weight increase.