Crop coefficients （Kc） of sugar beet were determined for accurate calculation of water requirements （CWR） and better irrigation water management. Three irrigation treatments were used during two seasons to measure...Crop coefficients （Kc） of sugar beet were determined for accurate calculation of water requirements （CWR） and better irrigation water management. Three irrigation treatments were used during two seasons to measure actual crop water use （ETc） under no soil stress treatment using gravimetric sampling. In the second season （SS）, the method was modified to target 8 temporal points during crop growth for smooth calculation of ETc under sufficient moisture supply to avoid the distortion that was created by the continuous gravimetric sampling after, before and during each irrigation cycle on the experimental plots. Water was stopped when each targeted sampling point was reached using large plots where intensive sampling continues until the crop reaches severe water stress or permanent wilting point （PWP）. The actual crop water use was extracted from the soil moisture depletion curve which allowed the identification of two clear segments. The first segment indicated crop water use during no water stress while the change of the slope indicated the beginning of the water stress. The reference crop evapotranspiration （ET0） was determined on daily basis using appropriate weather data that coincides with the ETc measurement and consequently the crop Kc were calculated. The results showed that the method used during the SS is easy and provides a better understanding of actual crop water use and better estimation of crop Kc. The calculated 10-day Kc values for sugar beet under heavy cracking clay soil conditions were： 0.46, 0.49, 0.53 and 0.60; for the initial stage： 0.69, 0.78, 0.88 and 0.97; for the development stage： 1.05, 1.11, 1.13, 1.11 and 1.04; for mid-season stage and for late season stage： 0.92, 0.74 and 0.60. Yield and other sugar related parameters were also presented for the two seasons.展开更多
The objectives of this study were to determine the characteristics of water consumption of seven forage cultivars, ryegrass （Secale cereale L.）, triticale （×Triticosecale Wittmack）, sorghum hybrid sudangrass ...The objectives of this study were to determine the characteristics of water consumption of seven forage cultivars, ryegrass （Secale cereale L.）, triticale （×Triticosecale Wittmack）, sorghum hybrid sudangrass （Sorghum biolor× Sorghum Sudanense c.v.）, ensilage corn （Zea mays L.）, prince’s feather （Amaranthus paniculatus L.）, alfalfa （Medicago sativa L.）, and cup plant （Silphium perfoliatum L.）, in response to climate variability （especially precipitation）. Field experiments were conducted at Yucheng Integrated Experiment Station from 2005 to 2009. Fifteen irrigated lysimeters were used to measure evapotranspiration （ET） and crop coefficient （Kc） of these seven forage varieties under ample water supply. The mean Kc for alfalfa is 1.08, and the mean Kc for other forage varieties ranges from 0.79 to 0.94. Kc for hibernating forage is higher in wet years than that in dry years, followed by normal years, while for annual forage, Kc is higher in dry years than in normal years, and is the lowest in wet years. For perennial varieties the order is normal years, dry years, and wet years. Among the annual varieties, ensilage corn is the first choice due to its highest average forage N yield and water use efficiency （WUE）. Sorghum hybrid sudangrass is another forage cultivar that grows well under all climatic conditions. It can achieve 1.08-2.31 t ha-1 y-1 N yield under all circumstances. Prince’s feather is sensitive to climate change and its N yield dropped below half even when ample water was applied in dry and normal years. Ryegrass and triticale have the advantage of growing in the fallow phase after cotton is harvested in the North China Plain （NCP） and the latter performed better. For perennial varieties, alfalfa performed better than cup plant in dry years. With ample irrigation, alfalfa can achieve higher biomass and WUE under arid climate condition, but excessive rain caused reduction in production.展开更多
文摘Crop coefficients （Kc） of sugar beet were determined for accurate calculation of water requirements （CWR） and better irrigation water management. Three irrigation treatments were used during two seasons to measure actual crop water use （ETc） under no soil stress treatment using gravimetric sampling. In the second season （SS）, the method was modified to target 8 temporal points during crop growth for smooth calculation of ETc under sufficient moisture supply to avoid the distortion that was created by the continuous gravimetric sampling after, before and during each irrigation cycle on the experimental plots. Water was stopped when each targeted sampling point was reached using large plots where intensive sampling continues until the crop reaches severe water stress or permanent wilting point （PWP）. The actual crop water use was extracted from the soil moisture depletion curve which allowed the identification of two clear segments. The first segment indicated crop water use during no water stress while the change of the slope indicated the beginning of the water stress. The reference crop evapotranspiration （ET0） was determined on daily basis using appropriate weather data that coincides with the ETc measurement and consequently the crop Kc were calculated. The results showed that the method used during the SS is easy and provides a better understanding of actual crop water use and better estimation of crop Kc. The calculated 10-day Kc values for sugar beet under heavy cracking clay soil conditions were： 0.46, 0.49, 0.53 and 0.60; for the initial stage： 0.69, 0.78, 0.88 and 0.97; for the development stage： 1.05, 1.11, 1.13, 1.11 and 1.04; for mid-season stage and for late season stage： 0.92, 0.74 and 0.60. Yield and other sugar related parameters were also presented for the two seasons.
基金this study was supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KSCX2 -YW-N-46-01)
文摘The objectives of this study were to determine the characteristics of water consumption of seven forage cultivars, ryegrass （Secale cereale L.）, triticale （×Triticosecale Wittmack）, sorghum hybrid sudangrass （Sorghum biolor× Sorghum Sudanense c.v.）, ensilage corn （Zea mays L.）, prince’s feather （Amaranthus paniculatus L.）, alfalfa （Medicago sativa L.）, and cup plant （Silphium perfoliatum L.）, in response to climate variability （especially precipitation）. Field experiments were conducted at Yucheng Integrated Experiment Station from 2005 to 2009. Fifteen irrigated lysimeters were used to measure evapotranspiration （ET） and crop coefficient （Kc） of these seven forage varieties under ample water supply. The mean Kc for alfalfa is 1.08, and the mean Kc for other forage varieties ranges from 0.79 to 0.94. Kc for hibernating forage is higher in wet years than that in dry years, followed by normal years, while for annual forage, Kc is higher in dry years than in normal years, and is the lowest in wet years. For perennial varieties the order is normal years, dry years, and wet years. Among the annual varieties, ensilage corn is the first choice due to its highest average forage N yield and water use efficiency （WUE）. Sorghum hybrid sudangrass is another forage cultivar that grows well under all climatic conditions. It can achieve 1.08-2.31 t ha-1 y-1 N yield under all circumstances. Prince’s feather is sensitive to climate change and its N yield dropped below half even when ample water was applied in dry and normal years. Ryegrass and triticale have the advantage of growing in the fallow phase after cotton is harvested in the North China Plain （NCP） and the latter performed better. For perennial varieties, alfalfa performed better than cup plant in dry years. With ample irrigation, alfalfa can achieve higher biomass and WUE under arid climate condition, but excessive rain caused reduction in production.
