Study on Evapotranspiration Characteristics of Flue-cured Tobacco Under Various Ecotype Area in China |
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Author | DuanShuHui |
Tutor | LongHuaiYu |
School | Chinese Academy of Agricultural Sciences |
Course | Soil |
Keywords | flue-cured tobacco evapotranspiration crop coefficient soil water meteorology |
CLC | S572 |
Type | Master's thesis |
Year | 2010 |
Downloads | 50 |
Quotes | 0 |
Water is an important environment factor, which strongly influences the growth of flue-cured tobacco. Study on evapotranspiration of tobacco field has great guidance and value on scientific irrigation, water use efficiency improvement and ensuring the quality and yield of flue-cured tobacco. Based on flue-cured tobacco planting partition and ecological regionalization, five areas were choosed. Meteorology (temperature, solar radiation, relative humidity, wind speed, rainfall, et al) and soil water content and water potential of tobacco field were collected by using in-situ monitoring technology. Variations of meteorological factors and soil water were studied. On this basis, reference crop evapotranspiration (ET0) was calculated by using Penman-Monteith equation, actual crop evapotranspiration (ETC) was achieved by using zero flux plane method, and crop coefficients (KC) were calculated based on above data. Variations of ET0, ETC and KC were fatherly analyzed, influence factors including meteorological factors and soil water were also discussed, the main conclusions are following:(1)There were great differences in meteorology and soil water status among sites, all of which had great volatile. Variation of soil water content and potential in growth diminished with depth; Dynamics of soil water storage mainly depended on water content of upper soil, both of them had similar variation law.(2)Daily average ET0 of tobacco field in Heilongjiang, Henan, Hunan, Guizhou and Yunnan were 3.8, 3.1, 2.6, 3.2 and 3.4 mm per day respectively. With tobacco growth, daily ET0 decreased gradually in Heilongjiang and Yunnan area, while increased gradually in Hunan area. There were significant(P<0.05) and highly significant(P<0.01) correlation between ET0 and air temperature, solar radiation, wind speed, relative humidity, sunshine hour and rainfall when all sites considered altogether, their correlations were 0.548**, 0.849**, 0.240*, -0.618**, 0.703** and -0.311** separately, but varied under different sites.(3) Parabolic law was showed in the dynamic of hourly ET0 in one day, From 5 am, ET0 was rising, reached its peak at noon, while reducing in afternoon, and dropped to the lowest level after 7:30 pm, bout 0.02 mm per hour.(4) According to magnitude of daily radiation and aerodynamic term in five sites, radiation term had larger contribution to ET0 than aerodynamic term, average radiation term at five sites were 2.5, 2.7, 2.9, 2.6 and 2.7 mm per day in growth, and aerodynamic term were 1.3, 0.2, 0.1, 0.6 and 0.6 mm per day separately, with tobacco growth, daily aerodynamic term diminished, thus the ratio of radiation to aerodynamic term raised, what was mainly caused by variety of wind speed.(5)Daily average ETC in Heilongjiang, Henan, Guizhou and Yunnan were 1.8, 1.5, 2.2 and 2.8 mm per day respectively, the change of daily ETC had a single-peak curve in the whole growing period, which increased gradually in root extending stage, reached peak in flourishing stage, while decreased in maturing stage.(6)There were significant (P<0.05) and highly significant (P<0.01) correlation between ETC of tobacco field and air temperature, solar radiation, relative humidity and sunshine hour in Heilongjiang area, their correlations were 0.298*, 0.356**, -0.292* and 0.270*, ETC model was acquired by using stepwise regression: ETC = ?1. 513+0.007Rs+0.100T (R2=0.190, F=8.303**).(7) Significant correlation between ETC and soil water content was found in Heilongjiang area, while not found in Guizhou, where soil water content of tobacco field was above field water capacity at most times. The correlations between ETC and 0-30 cm, 30-50 cm, 50-70 cm, 70-100 cm, 100-120 cm and soil water storage upon 120 cm were 0.407**, 0.529**, 0.533**, 0.427**, 0.265* and 0.470** respectively in Heilongjiang.(8)Daily average KC in Heilongjiang, Henan, Guizhou and Yunnan were 0.48, 0.62, 0.69 and 0.95 respectively, daily KC had a single-peak curve in the whole growing period. There is good relationship between KC and leaf area index, which had an s-curve trend before harvest.