| The water is very important for the yield and quality of flue-cured tobacco, and the water needed by the growth and development of flue-cured tobacco was different at different soil and area, so we designed the pot and field experiments at 2002-2003 year and studied the water requirement of flue-cured tobacco in the medium textured soil at Henan province, and established the model of water requirement of field preliminarily.(1) The research results of pot and field experiments at the medium textured soil of Henan province of 2002 and 2003 as follows: the suitable water for the growth and development of flue-cured tobacco was 55-65% of soil relative moisture at the growth stage of root, 75-85% at the rapid growth stage and 65-75% at ripe stage.(2) the water consume was very different for the same treatment of water at different weather condition. For the suitable water at field CK of Xiang cheng countty ,the water consume of root growth stage, rapid growth stage, the former of ripe stage was respectively 103.53mm,192.57mm,113.15mm at 2002 and 86.14mm, 176.80mm, 138.47mm at 2003 , the later of ripe stage and the whole growth was respectively 48.11mm and 449.52mm at 2003.(3)the crop coefficient at the medium textured soil of Henan province was stable for the suitable water although there was significant different forweather. The single crop coefficient and basal crop coefficient at initial stage corrected was 0.93 and 0.23 at 2003 at Xiangcheng county by the method of FAO-56, 1.13 and 1.09 at middle stage, 0.54 and 0.45 at end stage; the single crop coefficient and basal crop coefficient at science and technology garden of school was 0.93 and 0.24 at initial stage, 1.17 and 1.12 at middle stage. The soil evaporation coefficient varied with the water stage of surface layer, but they were stable at different weather.(4) the crop water requirement accounted by the method of double crop coefficient was more close to the actual value compared with the method of single crop coefficient. The absolute warp of Xiangcheng county at initial stage, development stage, middle stage and end stage was respectively -3mm, 5mm, -19mm, 2mm and -14mm at 2003, the relative warp was respectively 12.70%, 4.87%, -8.36% 3.08% and-3.08%; the absolute warp of initial stage, development stage, middle stage was respectively 2mm, 5mm, 10mm, the relative warp was 8.00%, 4.00% and 4.26% at technology garden of school at 2003; the absolute value was all equal or lower than the . account result of single crop coefficient.(5)the model of water requirement of flue-cured tobacco at the medium textured soil of Henan province was ETm=KcmXET0 based on the double crop coefficient of Xiangcheng county at 2003. the ETm represents water requirement of flue-cured tobacco; ETO represents the reference water requirement of the reference crop at account stage , Kcm represents the coefficient of model of account stage, and the stages were changed incessantly , the 0-20d after transplanting( just enter the growth stage of root ), 20-40d, 40-80d(the harvesting of lower leaf ended, the middle leafenter the ripe stage), 80d until the end was respectively 1.05, 1.28, 1.49 and 1.25.The model could forecast the water requirement of flue-cured tobacco at the stage of development at Zhangrang of Henan province validated by the experiments of 2002 and 2003.The absolute warp and relative warp between the water requirement of crop accounted by the model of water requirement and that accounted by the actual measurement was both little. The relative warp of Xiangcheng county at initial stage, development stage, middle stage, end stage and the whole stage was respectively -11.54% 4.42% 9.2% -3.08% , and the relative warp of Xiangcheng county at initial stage, development stage and the former of middle stage was respectively -21.74% 5.97% -1.20% at 2003, the relative warp of science and technology garden of school at initial stage, development stage, middle stage was respectively 4.00% 4.80% 2.55% at 2003, the error of base model was al... |
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