Closed-type Transplant Production System Research Articles

Development of a Simplified Closed-type Transplant Production System and Its Potential for Tomato Seedling Production during Winter in the Kurdistan Region, Northern Iraq

Development of a Simplified Closed-type Transplant Production System and Its Potential for Tomato Seedling Production during Winter in the Kurdistan Region, Northern Iraq

Number of Sweetpotato Propagules Produced, Electric Energy Consumption and Storage Root Yield after Transplanting in the Field, as Affected by Planting Density in Closed Type Transplant Production System

Number of Sweetpotato Propagules Produced, Electric Energy Consumption and Storage Root Yield after Transplanting in the Field, as Affected by Planting Density in Closed Type Transplant Production System

閉鎖型苗生産システムに設置した家庭用エアコンの冷房時成績係数

Electric energy consumption for cooling (Wc) and the coefficient of performance for cooling (C) were investigated in a closed-type transplant production system (CTPS). C is defined as the ratio of heat energy absorbed by the evaporator of the air conditioner to Wc. A Basic Module Room with thermally insulated walls (5.8 m (W), 2.7 m (L), 5.4 m (H)) in the Research Unit for Closed Plant Production Systems at Chiba University was considered as a model CTPS. Home-use air conditioners, fluorescent lamps, fans and humidifier were installed in the CTPS. One hundred fifty-one data sets were collected for the analysis during the period from 1 May 2000 to 30 April 2001 when air temperatures inside the CTPS (Tin) during photo-and dark period were 29-31°C and 27-29°C, respectively. The chemical energy assimilated by the transplants was considered to be negligible. In the preliminary study, the number of air exchanges of the system was found to be 0h-1 Heat energy transmission through the walls was estimated as the product of heat transmission coefficient (ceiling and side walls : 0.3 W m-2 k-1 floor : 0.2 W m-2 K-1) and the air temperature difference between inside and outside the CTPS. Subsequently, C was estimated by dividing the heat energy generated inside the CTPS (Q) by Wc. Wc increased with increasing air temperature outside the CTPS (Tout) and with increasing Q. Most (72-86%) of the electric energy was consumed by lamps. The rest was consumed by air conditioners (7-17%) and other equipments (5-15%). The average value of C was 7.6 under this experiment condition. The estimated values of C were 1.1-2.6 times greater in this experiment condition than the catalog value measured in the standard condition (Tin : 27°C, Tout : 35°C), because Tout was lower than Tin. C increased with decreasing Tout and with increasing Q. These results show that C of a recent model of home-use air conditioner is relatively high, and its application is beneficial for reducing Wc in the CTPS.

自律分散制御に基づく環境制御システム

An environmental control system proposed here was named the decentralized autonomous production management system (DAPMS). It was constructed based on the idea that each plant individual itself could require the desirable environment to the plant production equipments and growers to attach small computer chips. In the DAPMS, each plant individual is an element whose production state and goal are known. A potential function based on this information expresses how well the goals of each element are satisfied. The global discipline in the DAPMS was kept using the potential function in each plant individual. A simulation model of the DAPMS was developed to test this idea. In the simulation, different parts of the growing room were characterized by different environmental variables to reflect the situation in a real transplant production facility. Each plant individual was moved (for example, by a robot) to the place within the growing room that was best suited for its growth. A reasonable arrangement of the plant individuals was obtained by the DAPMS, even when changes were made in the scale of the facility, the number of plants, and other variables. The DAPMS was applied to cell tray production of sweetpotato transplants in a closed-type transplant production system. Even though the growing room had uneven environmental conditions and a variety of transplant individuals, the DAPMS was able to provide a desirable environment to the transplant individuals and to produce transplants with a uniform number of leaves.

閉鎖型苗生産システムにおける消費電力量および電力コストの解析

閉鎖型苗生産システムにおける消費電力量および電力コストの解析

閉鎖型苗生産システムのナスセル成型苗育成時における電気エネルギおよび水消費量

閉鎖型苗生産システムのナスセル成型苗育成時における電気エネルギおよび水消費量

閉鎖型苗生産システムにおけるサツマイモ植物個体群の純光合成速度の経日変化

The objectives of this study were to estimate 1) the net photosynthetic rate of sweetpotato plants canopy (Pcn) using Monsi and Saeki's mathematical model, and 2) the increase in dry weight of plants in closed-type transplant production system. The Pcn 2, 6, 9, 12, 13 and 14 d after planting were estimated to be 2, 8, 10, 17, 18 and 17 μmol m-2 s-1, respectively. Measured and estimated values of increase in dry weight per plant for 15 d were 337 and 357 mg, respectively. The maximum light utilization efficiency (Pcn divided by photosynthetic photon flux (PPF) on the tray surface) 2, 6, 9, 12, 13 or 14 d after planting was found at the PPFs of 10, 191, 260, 321, 323 or 360 μamol m-2 s-1, respectively. Hence, the electric energy consumption for lighting was reduced by 35% when PPFs were set at 50, 200 and 300pmol m-2 s-1 O-4, 5-8 and 9-14 d after planting, respectively, as compared with a constant PPF of 300μmol m-2 s-1, under the present experimental conditions. These results indicate that the mathematical model for estimating growth of sweetpotato plants can be applied to the energy conservative control of the environment (e.g., PPF) in the closed-type transplant production system.

閉鎖型苗生産システムのエネルギおよび物質収支 （第３報） 二酸化炭素収支

閉鎖型苗生産システムのエネルギおよび物質収支 （第３報） 二酸化炭素収支

閉鎖型苗生産システムのエネルギおよび物質収支 （第２報） 水収支

Water balance of the closed-type transplant production system with artificial lighting was investigated. Sweetpotato (Ipomoea batatas (L.) Lam. cv. Beniazuma) plants were grown for 15 days at photosynthetic photon flux (PPF) on the tray surface of 100, 200 and 300 μmol m-2 s-1 on days 0-2, 3-11 and 12-14, air temperature of 30°C, CO2 concentration of 1000 μmol mol-1, relative humidity of 80/100% (photoperiod/dark period) inside the system and photoperiod of 16 h d-1. Daily amounts of evapotranspirated and dehumidified water were increased with time due to increases in evapotranspiration area and PPF. Daily amount of dehumidified water was 90-95 % of the sum of evapotranspirated and humidified water. The amounts of irrigated, evapotranspirated, humidified and dehumidified water during the experiment were 49.5, 36.7, 24.3 and 55.9 kg m-2, respectively. Water contents of plants and soil at the end of the experiment were 1.6 and 10.8 kg m-2, respectively. Water utilization efficiency of the system was 0.93. These results show the amount of water use for transplant/plant production can be decreased to 24% of the amount of irrigated and humidified water when dehumidified water was reused for irrigation and humidification. Thus, the closed-type transplant production system is suitable for minimizing the water use in transplant/plant production.

閉鎖型苗生産システムのエネルギおよび物質収支 （第１報） エネルギ収支

The energy balance of a closed-type transplant production system with artificial lighting was investigated. Sweetpotato (Ipomoea batatas (L.) Lam. cv. Beniazuma) plants were grown for 15 days at photosynthetic photon flux on the tray surface of 100, 200 and 300 μmol m-2 s-1 on days 0-2, 3-11 and 12-14, respectively, air temperature of 30°C, CO2 concentration of 1000 μmol mol-1, relative humidity of 80/100% (photoperiod/dark period) inside the system and photoper-iod of 16 h d-1. The amount of electric energy consumption during the 15 days for lighting, cooling and the other equipment per planting area were 375.5, 80.8 and 41. 1 MJ m-2, respectively. Electric energy consumption per plant was 1.8 MJ (0.5 kWh), and its cost was approximately 4-5 Japanese Yen. Coefficient of performance for the cooling system was approximately 4.7, which was 2 times higher than the value described in the catalog, partly because the air temperature inside the system was higher than that of outside the system. The ratio of electric energy consumption to chemical energy assimilated by plants (energy use efficiency of the system) was 0.006. These results show that the closed-type transplant production system is feasible for the commercialization. Methods for further reduction of electric energy consumption (increasing the energy use efficiency of the system) and electricity cost are discussed.

閉鎖型苗生産システムにおける電気エネルギ消費量削減のための光合成有効光量子束調節

Sweetpotato plants were grown for 15 d under stepwise photosynthetic photon flux (PPF) and two levels of constant PPF conditions. In stepwise PPF condition, the PPFs were set at 100, 200 and 300μmol m-2 s-10-4, 5-9 and 10-14 d after planting, respectively. PPFs of 200 and 300μmol m-2 s-1 were chosen as the constant PPF conditions. Under same integrated PPF (PPF×photoperiod×experimental period), dry weight per plant 14 d after planting was 1.1 times higher in stepwise PPF condition than in constant PPF condition. The increase in dry weight per electric energy consumption of lamps was 1.1 times higher in stepwise PPF condition than in constant PPF conditions. Therefore, stepwise PPF control is a useful method for reducing electric energy consumption and increasing electric energy utilization efficiency (chemical energy contained in plants/electric energy consumption of the system) of the closed-type transplant production system.