Study On The Factors Limiting The Yield Of Greenhouse Tomato In Tai Yuan District

The greenhouse crop production in Tai Yuan district has been lower than that of the developed countries. For solving this problem, scientists have taken many measures, for example, introducing modern greenhouses and good cultivars from abroad, and improving greenhouses management. But the ideal goal has not been achieved yet. So, in order to find the real reason that resulted in the trouble, the condition of radiation and temperature in Tai Yuan district was studied and compared to those of Holland in the paper, meanwhile the net leaf photosythetically rate of tomato was simulated. The results were showed as following: 1. The yearly accumulative radiation in Tai Yuan district was 1630MJ higher than that in Holland. In the period from April to September, the monthly accumulative radiation and the daily accumulative radiation in Tai Yuan district were 90MJ and 3MJ higher than that in Holland respectively. However, in the period from October to May, the monthly accumulative radiation and the daily accumulative radiation in Tai Yuan district were 180MJ and 6 MJ higher than that in Holland respectively. It was concluded that there was good solar radiation in Tai Yuan district, compared that in Holland, especially in the period from October to May. The atmosphere transmissivity in the two places for the average annually was 0.48 in Tai Yuan district and 0.37 in Holland. 2. Average daily temperature for whole year was nearly the same for Tai Yuan district and Holland. The maximum temperature in summer frequently was above 35℃, even up to 40℃, in Tai Yuan district but was only 27℃in Holland. The minimum temperature in winter was -18℃in Tai Yuan district and –4℃in Holland respectively. It can be concluded that the apparent difference of the temperature between the two places lied in the maximum and minimum temperature. The difference of day-night temperature that was 4~7℃in Tai Yuan district was 1~4℃higher than that in Holland. The temperature sum during the whole year was 4080℃·d in Tai Yuan district compared 3599℃·d in Holland. 3. The net leaf photosynthetic rate of greenhouse tomatoes was simulated using FST software that was introduced from Holland. The model used for the simulation is TOMSIM. In the model, inputting the radiation and the average temperature the net leaf photosynthetic rate of greenhouse tomatoes in Tai Yuan district was a little bit higher than that in Holland. Inputting the daily maximum temperature in the model, however, the net leaf photosynthetic...