To obtain basic information about introducing crops to a rooftop that receives little sunshine, growth and development of rice was investigated under semi-shaded and sunny conditions on a flat roof in 2007 and 2008. Paddy rice cultivars Nipponbare, Nakateshinsenbon, and Takanari were analyzed in this study, and some other cultivars were also planted in containers. Two types of soil were used, namely paddy soil and mixed soil, including “Acre” recycled soil originating from a water purification plant (Arakida : sand : Acre=7.0 : 1.5 : 1.5). Semi-shade was provided by two metal screens located on the east and west sides of a container. Daily solar radiation in the semi-shaded plot was approximately 50% of that in the sunny plot. The number of panicles per hill in the semi-shaded plot was 34-98% less than in the sunny plot. Tiller number was highest (65-98%) for Nakateshinsenbon, suggesting that this cultivar might be suitable for cultivation under semi-shaded conditions. In sunny and semi-shaded plots, the number of tillers on the 35th day after planting decreased curvilinearly with the decrease in accumulated solar radiation between the 1st and 30th day after planting. The percentage of ripened grains tended to decrease with reduced solar radiation (averaged over 10 days from the 15th day after full heading date) and with increment in the number of spikelets per plant. Grain yield in the semi-shaded plot compared to the sunny plot was 29% (paddy soil) and 38% (mixed soil) for Nipponbare, and 41% and 57%, respectively, for Nakateshinsenbon. Not a large differences in growth and development of Nakateshinsenbon were observed between paddy soil and mixed soil. Our results suggest that when rice is introduced to a rooftop garden under semi-shaded conditions, it should be planted considering planting density to promote tillering, and cultivars should be chosen that can adapt to mixed soil, including recycled soil.

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Windbreak nets and plant windbreaks are effective in suppressing maize pollen dispersal and crosspollination. This paper seeks effective arrangements of windbreak nets or plant windbreaks to suppress cross-pollination from a 50 m square maize donor plot. A pair of numerical models, the A2Cflow and A2Ct&d, which had previously validated the pollen dispersal and cross-pollination in the maize plot, were used. 3-m tall 1-mm mesh nets and 2-m tall sorghum windbreaks were confirmed to be effective in suppressing cross-pollination in a 1.8-m tall maize plot. The isolation distance for a 0.9% criterion of cross-pollination rate was reduced from 50 m without a windbreak to 22 m when four lines of windbreak nets were arranged. The wind speed was 3 ms^-1. In commercial cultivation, plant windbreaks may reduce installation and labor costs rather than windbreak nets. Three lines of plant windbreaks are equivalent to a one line windbreak net in suppressing cross-pollination.

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To examine the dependence of sap flow velocity (SFV) on the environmental variables in an urban wooded area, diurnal and seasonal variations in SFV of deciduous broad-leaved trees (Quercus acutissima Carruthers) and meteorological and soil parameters were measured from April to November 2009 in Minami-osawa campus, Tokyo metropolitan university. The SFV values were determined by a Granier method. On a sunny day, SFV increased rapidly in the morning and decreased rapidly in the evening, but it was relatively stable at midday. On cloudy and rainy days, the SFV values followed the changes in global solar radiation and vapor pressure deficit. The result of lag correlation analysis for all of the study period indicated that the diurnal variation in SFV was highly related to solar radiation with a time lag of 1-2 h and moderately related to vapor pressure deficit and air temperature without a time lag. Seasonally, the daily values of SFV fluctuated sharply depending on the weather conditions. SFV on sunny days increased during April and May, and reached its maximum value in June, and decreased rapidly in November. The seasonal variation in SFV was strongly affected by daily solar radiation and daily vapor pressure deficit, and the relationship between SFV and solar radiation were well expressed by a rectangular hyperbolic function. But data of April and May indicated a significantly low value relative to other months. These results suggest that seasonal change in the SFV may depend on not only meteorological parameters but also the phenological stage of the tree. The SFV residuals of the solar radiation model did not show strong correlation with vapor pressure deficit, air temperature, wind speed, or soil water content. The daily values of SFV depended on the meteorological parameters especially on cloudy days and rainy days. In addition, it was shown that SFV without data of vegetative stage and exfoliation stage clearly depends on meteorological parameters.

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In Japan, meteorological observatories are located mainly in urban areas, thus the surface air temperatures (SATs) observed at these sites contain the anthropogenic urban effect. For the estimation of such urban bias or for agro-meteorological usage, we need meteorological and climatological data that exactly reflects the agro-meteorological environment. This study aims to select monitoring AMeDAS stations located on agricultural land (referred to by the acronym “MAA”) in Japan for this purpose.
65 AMeDAS stations in every prefecture except for Tokyo were identified as MAAs. In selecting a MAA, we considered several factors such as the increasing rate of SAT (from 1980 to 2007), both the occupation rate of the agricultural land and that of the urban area around the MAA, the rate of expansion of the urban area around the agricultural land, and the local environment around the MAA. The increasing rates of the SATs of the selected MAAs were different in each region, with the values in western Japan being higher compared with those in northern Japan.
The increasing rates of the minimum SATs of 65 MAAs were a little lower than that of the 17 general meteorological observatories selected by the Japan Meteorological Agency, except for that of western Japan. These features show that the 65 MAAs weren’t strongly affected by urban bias, but we also found that SATs could be influenced by urban effects to some extent even for the AMeDAS stations located on agricultural land. That is, the increasing rates of the agricultural land SATs are possibly not always the same as those of background SATs in Japan.

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We devised an apparatus (the SolarPump) that transports water from a reservoir to the distillate collection at a distance while distilling the water, using solar energy alone. The basic component of the system is a vaporizer, which is enclosed with a condenser. The vaporizer is based on the same principle as a porous cup atmometer. The potential energy level of water, which is lowered at the evaporating surface of a porous material when energy is provided for evaporation, causes water to flow continuously along the gradient of the potential energy from a reservoir to the evaporating surface. In other words, the system conduit is completely filled by water all the time, as long as energy and water are supplied. To confirm the above principle and evaluate its performance, we conducted a series of field tests using an experimental apparatus supplied with tap water. Its vaporizer included a vessel made of a transparent plastic tube, which is capped with a porous cup on the top and is open at its distal end into the reservoir. The condenser was supported and sealed with an acrylic outer tube. The apparatus yielded distillate proportional to the global irradiance, while transporting water 0.5 m above the reservoir. We also confirmed that the apparatus was capable of transporting water 2.0 m above the reservoir while performing distillation.

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