A growth model for leaf lettuce grown in a greenhouse environment was developed. The experiments were conducted in a plant production facility located at Ibaraki University, Japan from January to November 2003. Each experiment took 37 days, namely 7 days for germination and 30 days after transplanting to a hydroponic system. The combinations of photosynthetic photon flux density of 140 to 200 μmol m−2 s−1 and CO2 concentration of 400 and 1200 μmol mol−1 were varied as the experimental treatments. Lettuce weights were measured 2 to 3 times a week, and the weight and number of leaves at harvest, 30 days after transplanting, were measured. A model was developed to fit the growth data using the Gompertz function, which has three coefficients. We found two of the three coefficients can be fixed at certain values within the range of our experimental conditions, and the last coefficient is closely related to fresh weight at harvest. An accurate prediction of lettuce weight at any number of days after transplanting can be achieved. The developed growth model shows a typical growth curve to thirty days as transplants respond to the input environmental conditions. Using this model, growers can identify when their plants will attain the desired target weight based on their greenhouses' environmental settings. This model may be applicable as a tool for planning production schedules and to help management strategy.
An image processing system for investigating plant morphological characteristics of two or more plants was developed and demonstrated. A CCD camera was mounted on a stepping motor with ten plants equally spaced around it. A computer captured and stored the image of the first plant, rotated the stepping motor 18 degrees and captured the image of the second plant. This operation was repeated until all plant images were captured. In order to achieve similar gray levels during day and night photography, image acquisition was performed using an 850 nm infrared LED as a light source as well as an infrared filter attached to the CCD camera. The stored images were analyzed using sub-pixel estimation with area-based pattern matching techniques. The reference image size within the sub-pixel pattern matching process was evaluated. It was clear that the reference image greater than 15×15 pixels in dimension was capable of detecting a 0.1 pixel displacement in plant images used as part of this research. This system was employed to measure stem elongation in ten Chrysanthemum morifolium Ramat ‘Reagan’ plants every 10 min for three days. Daily variations in stem elongation were clearly observed and it was found that stem elongation was greater during the night than during the day. Substantial increases occurred during the first two hours of night conditions.
In Japan, Horticultural activity improves the quality of life for all people by beautifying neighborhoods, stimulating social inter-action, producing nutritious food, encouraging self-reliance, conserving resources, and creating opportunities for recreation and education. However, the psychological effects of horticultural activities in community based programs have not been discussed in as far as they provide useful tools to improve quality of life. In this study, subjects (61 in total, 22 men and 39 women, mean age=46) were engaged in activities related to horticulture: active participation involved planting non-flowering pansy plants while passive participation involved observing a community garden. One group engaged in active participation was given 2 h to garden while two other groups were given 6 h to complete their Horticultural Activity (HA). POMS data for all groups was collected both before and after of their gardening activities. The 6 h HA group members in experiment 3 filled out the POMS form 2 h into the activity in addition the before and after inventories. The overall POMS score for 2 h of horticultural activity was significantly higher than that of simply observing for 2 h. The greatest psychological effects were found among the group that engaged in 2 h of horticultural activity. The result suggests that 2 h of horticultural activity induces the best psychological effects. Thus, the POMS scores indicate that horticultural activities have positive psychological effects under suitable conditions. These findings indicate that horticultural activity improves mood state, suggesting that it may be a useful tool for community based programs aiming to reduce stress. Therefore, to the extent that horticultural activities contribute to community residents' stress reduction, these findings support the role of horticultural activity as an effective component of community based programs. A principal goal for community based programs is establishing the conditions that will encourage individuals to participate. The benefits of stress reduction gained from 2 h of horticultural activity may be an important condition for sustainable participation.
The effects of timing of high temperature treatment around watermelon fruit during the fruit enlargement were investigated with respect to the sugar content and cell size in the central, intermediate (between the two placental sectors) and outer regions of fruit. Fruit growth was significantly accelerated during high temperature treatment regardless of its timing. Cells in the central region of fruit enlarged more actively from 10 to 20 days after anthesis (DAA) at higher temperatures, but high temperature treatment after 20 DAA resulted in cell enlargement in the intermediate and outer regions of fruit. With the exception of sucrose content in the central and intermediate regions of fruit, sugar contents at harvest time increased with high temperature treatment from 10 to 20 DAA, whereas high temperature treatment after 20 DAA reduced sugar levels throughout the fruit. These results suggest that active cell enlargement in the central region of fruit during the early stage of the fruit enlargement caused by high temperature promote sugar accumulation in fruit during maturation.
The effects of high (day/night=30/25°C; H) and low (23/17°C; L) air temperatures on the development of pistillate flowers (PFs) during the seedling stage were clarified in 7 cucumber cultivars (Cucumis sativus L.) in order to identify potential high-yield cultivars in summer. Most of the cultivars developed nodes at a higher rate with H treatment than with the L treatment; however, the number of PF nodes and the total number of PFs on a plant were decreased with the H treatment in ‘028’ (multi-pistillate monoecious cultivar), ‘NK×AN8’ (mono- or di-pistillate gynoecious cultivar) and ‘Toyooka’ (multi-pistillate gynoecious cultivar). With H treatment, ‘028’ and ‘NK×AN8’ bore one PF or less per node, while ‘Toyooka’ produced 1.7 PFs per node. When the ‘028’ and ‘NK×AN8’ cultivars were grown in spring and summer, the PF numbers per PF node during summer were lower in the ‘028’ cultivar but not in ‘NK×AN8’. The fruit abortion rate was higher in summer in both cultivars, and it was reduced slightly by pollination. This study suggests that gynoecious cultivars could achieve a high yield in summer within a short growing period because they bear more PFs per node than multi-pistillate cultivars, and the effect of pollination on fruit abortion was too small to realize a high yield in summer.
This is the first report of light-dependent monoterpene emissions from an oak species native to Asia. Isoprenoids emitted by Quercus phillyraeoides were measured using branch enclosure methods. Sabinene, and α- and β-pinenes were the major compounds accounting for more than 90% of the total monoterpene emissions. The basal emission rates of total monoterpenes on leaf area and leaf dry weight bases ranged from 0.07 to 6.30 nmol m−2 s−1 and from 0.22 to 14.3 μg g−1 h−1, respectively. A proton transfer reaction mass spectrometry measurement revealed that the emissions depend significantly on light intensity and leaf temperature. Q. phillyraeoides may be taxonomically close to European monoterpene-emitting oaks because it is morphologically close to the oaks native to the Mediterranean area, and because the geographical features of their habitats are similar to each other.