The effect of container porosity on root environment and plant growth
SummaryComparison of clay and plastic pots for tomato propagation in six experiments showed plastic pots to give significantly better results than clay pots in winter and the converse to be true in summer. In each experiment the ratio of plant growth (dry weight) in clay and plastic pots was related to both the mean daily solar radiation and the mean outside night minimum temperature. In winter, plants in both types of container made significantly more growth when stood on open benches than when stood on benches with solid surfaces.These differences in growth were related to soil temperature, clay pots being cooler than plastic pots, the temperature difference between the types of pot ranging from approximately 1°C by night in winter to 4°C under high intensity solar radiation in summer. In winter, soil temperatures were often below the optimum, and in summer in excess of the optimum.By day, temperature within the pots showed highly significant correlation with solar radiation, and by night in winter pot temperature was negatively correlated with the difference between the glasshouse and the outside air temperature.Well-defined horizontal thermal gradients were found, and these were positively correlated with soil temperature. In wet soils the thermal gradients were less than in dry soils, and because of their higher thermal conductivity wet soils were warmer than dry soils.When the normal evaporative cooling from the porous walls of clay pots was prevented by a bituminous coating, the soil temperature during the night was not significantly different from that in plastic pots. By day, however, soil temperature in non-evaporating clay pots was less than that in evaporating clay pots, due to the lower thermal conductivity of the dry clay wall.
Effect of azimuth and pot color on the variation of pot surface and growing media temperature
The effect of azimuth and pot color on the variation of pot surface and growing media temperature was studied. Four pot colors that including with black, brown, silver and white color were used. The growing media comprised with soil : rice husk : coconut dust at 1:1:1 ratio. From the result of this study, the azimuth and pot color effected the variation of pot surface temperature. The azimuth effected the variation of pot surface temperature at 8.00, 10.00, 14.00, and 16.00. At 8.00 and 10.00, pot surface temperature in east direction was the highest, while at 14.00 and 16.00, pot surface temperature in west direction was the highest. Whereas, pot color effected the variation of pot surface temperature at 8.00, 10.00, and 14.00 with black color was the color that had the highest 33.3, 39.1 and 46.4C, respectively. On the other hand, the white color was the color that could the highest reduces the pot surface temperature when compared with the temperature of black pot color, which were 4.6, 3.9 and 4.3C lower than that in a black pot, respectively. Not only, the effect on the variation of pot surface temperature, pot color was also affected on the RMUTP Research Journal Special Issue 432 วารสารวิชาการและวจิัย มทร.พระนคร ฉบับพิเศษ การประชุมวิชาการมหาวิทยาลยัเทคโนโลยีราชมงคล ครั้งที่ 5 variation of growing media. Pot color effected the variation of growing media temperature during 8.00 to 18.00. When compare the growing media temperature among the pot color with that in black pot color which was the highest temperature, white color pot was the highest efficiency to reduce the growing media temperature, especially, at 10.00 and 12.00. White pot color could reduce the growing media temperature about 5C, follow by silver color pot was about 3C, while the growing media temperature in brown color pot was not difference with that in black color pot. ค าส าคัญ : มุมทิศ สีกระถาง อุณหภูมิผิวกระถาง อุณหภูมิวัสดุปลูก
Secoiridoids from Olea europaea
Abstract Three new secoiridoids have been isolated from the leaves of Olea europaea along with the previously reported. The compounds were identified by spectral means.