Effects of Plant Population and Film Mulch on Physiological Characteristics of Canopy and Moisture Utilization Efficiency of Flue-cured Tobacco Field Soil

The effects of plant population and film mulch on physiological characteristics of canopy and moisture utilization efficiency of flue-cured tobacco field soil were studied in field experiments. The results showed that with the increase of plant population, the leaf area index of flue-cured tobacco, relative humidity at tobacco field, stomatal conductance, rate of transpiration and CO2 concentration in interstitial space of leaf were increased, while the photosynthetic effective radiation quantity, leaf temperature and net photosynthetic rate were decreased. It was also found that the field evapotranspiration increased, the water content within 0-60cm soil depth decreased with the increase of plant population, the water deficiency became more serious. Film mulch had significant effects on preservation of soil moisture in the early stage of tobacco growth, but it became less obvious in the middle and later stages. Comprehensive analysis from the points of tobacco's economic properties and field moisture utilization efficiency indicated that the appropriate plant population of flue-cured tobacco was 16500-19500 plants per ha.