The Research Of Relationship Between Temperature And Light Environment In Solar Greenhouse And Growth Period Of Lettuce Grown In Matrix Culture

Greenhouse crops are affected by different environmental factors in the process of growth and development.Temperature and solar radiation,as the two most important environmental factors,have different effects on different growth and development stages of crops.In this experiment,the growth period of lettuce was divided into seedling growing period and harvesting period.The seedling growing period was from sowing to planting,and the harvesting period was from planting to harvesting.By measuring the temperature and solar radiation in the greenhouse during different sowing periods of lettuce in summer,autumn and winter,the relative thermal effect and accumulated radiant heat accumulation were calculated,and the relationship between the growth period and accumulated radiant heat accumulation of lettuce in different sowing periods was explored.The main conclusions were as follows: the accumulated radiant heat accumulation needed for lettuce to complete its growth and development was not one.The constant value varies with the change of the average photosynthetic active radiation range in different seasons,but the accumulated radiation heat required for lettuce growth varies slightly within the same average photosynthetic active radiation range.When the average photosynthetic active radiation ranged from 133.60 to 148.52W/m~2,91.50 to 131.37W/m~2 and 73.41 to 84.27W/m~2,the cumulative radiation heat integrals of lettuce were 619.75±4.15MJ/m~2,384.21±0.92MJ/m~2 and408.21±0.28MJ/m~2,respectively.Comparing the measured daily total radiation heat accumulation with the accumulated radiation heat accumulation required for lettuce growth,the formula of lettuce growth rate and the formula of growth stage can be obtained.When the growth stage is accumulated to 1,the lettuce can be harvested.Compared with other growth and development models,this growth rate formula is simple in calculation and has fewer parameters.It can be applied to actual production to determine the growth stage of lettuce.This study independently designed the greenhouse lettuce production planning decision-making system.The system organizes the test data into a historical database,takes the growth rate formula and the growth stage formula derived from the test as the core support formula,and has the self-learning function.It can expand the new production data into the historical database to continuously optimize and update the test formula.After the farmers input lettuce production plan into the system interface,the system predicts the harvest time of the lettuce,informs the growth stage of the lettuce,and gives the most reasonable production decision.Understanding the growth stage of lettuce and the cumulative radiation heat accumulation required to complete all growth stages,under the premise of formulating production plan,we can realize the goal of early planting,harvesting and listing by adjusting the temperature and light environment in greenhouse,so as to improve economic benefits.At the same time,the system plans to adopt the method of external sensors,which can be used for farmers to choose instruments independently.The proposed system has few applications in lettuce cultivation and production in China,but it is of great significance to lettuce growers.Compared with other agricultural application systems,it has the advantages of simple operation,visual display,and so on.It is convenient for farmers to formulate production plans for the whole year.The experimental data and system in this study provide data support and theoretical basis for subsequent instrument development.The application and promotion of the instrument will be realized after the completion of the follow-up work.