A large portion of irrigation farmers make use of subjective （intuition） irrigation scheduling methods as supposed to objective or scientific irrigation scheduling methods, which need to be changed. The BEsproeiings...A large portion of irrigation farmers make use of subjective （intuition） irrigation scheduling methods as supposed to objective or scientific irrigation scheduling methods, which need to be changed. The BEsproeiingsWAterbestuursprogram （BEWAB＋） irrigation scheduling programme is based on the water balance equation and needs： （1） a crop production function; （2） a relative consumptive water demand curve and （3） an allowable depletion subroutine. The objective of this paper was to describe research aimed at obtaining information on （1） and （2） for pea and also to describe the effect of water application on yield and water use of pea. BEWAB＋ uses this information to estimate the daily irrigation water requirements for a particular soil-crop-atmosphere system under irrigation. A field experiment, based on published line-source irrigation methodology, was conducted on a 3 m deep loamy fine sand Bainsvlei or Ustic Quartzipsamment soil near Bloemfontein （26°08′S; 29°01′E） in South Africa. Results showed that there is a linear relationship of the form Ys = 8.07ET - 249 （r2 = 0.91）, where Ys is the seed yield of pea （kg/ha） and ET is evapotranspiration for the growing season （mm）. The relative consumptive water demand curve is represented by the following third order polynomial function that describes the relationship between time and relative ET for a pea growing season of 120 days： ETrelx = 0.09419646 - 0.01302413x ＋ 0.00059008x2 - 0.00000371x3. ETrelz denotes relative ET and x denotes time in days. A workable balance between practical problem solving and advanced irrigation science has been established with BEWAB＋. Pre-plant irrigation schedules can be made for semi-arid areas with the BEWAB＋ programme using easily obtainable inputs, like target yield, soil depth and soil particle size distribution information.展开更多
Various cadmium （Cd） concentrations （0, 50, 100, 200 and 300 μmol L-1） affected Elymus dahuricus seed germination, seed- ling growth, antioxidative enzymes activities （AEA）, and amounts of malondialdehyde （MDA...Various cadmium （Cd） concentrations （0, 50, 100, 200 and 300 μmol L-1） affected Elymus dahuricus seed germination, seed- ling growth, antioxidative enzymes activities （AEA）, and amounts of malondialdehyde （MDA） and proline present. These in- fluences were determined for separate E. dahuricus cohorts known to be either infected （E＋） or non-infected （E-） by a Neo- typhodium endophyte. Under high Cd concentrations （100, 200 and 300 lamol L-l）, E＋ specimens showed a significantly （P〈0.05） higher germination rate and index, as well as higher values for shoot length, root length and dry biomass. However, the germination rate and index, root length and dry weight did not show a significant （P〈0.05） difference under the low Cd concentrations （0 and 50 μmol L^-1）. AEA and proline content increased, as did MDA content, in the E＋ （vs. E-） specimens under high Cd concentrations. There was no significant （P〉0.05） difference under low Cd concentrations. Endophyte infection was concluded to be of benefit to E. dahuricus exposed to high Cd concentrations.展开更多
文摘A large portion of irrigation farmers make use of subjective （intuition） irrigation scheduling methods as supposed to objective or scientific irrigation scheduling methods, which need to be changed. The BEsproeiingsWAterbestuursprogram （BEWAB＋） irrigation scheduling programme is based on the water balance equation and needs： （1） a crop production function; （2） a relative consumptive water demand curve and （3） an allowable depletion subroutine. The objective of this paper was to describe research aimed at obtaining information on （1） and （2） for pea and also to describe the effect of water application on yield and water use of pea. BEWAB＋ uses this information to estimate the daily irrigation water requirements for a particular soil-crop-atmosphere system under irrigation. A field experiment, based on published line-source irrigation methodology, was conducted on a 3 m deep loamy fine sand Bainsvlei or Ustic Quartzipsamment soil near Bloemfontein （26°08′S; 29°01′E） in South Africa. Results showed that there is a linear relationship of the form Ys = 8.07ET - 249 （r2 = 0.91）, where Ys is the seed yield of pea （kg/ha） and ET is evapotranspiration for the growing season （mm）. The relative consumptive water demand curve is represented by the following third order polynomial function that describes the relationship between time and relative ET for a pea growing season of 120 days： ETrelx = 0.09419646 - 0.01302413x ＋ 0.00059008x2 - 0.00000371x3. ETrelz denotes relative ET and x denotes time in days. A workable balance between practical problem solving and advanced irrigation science has been established with BEWAB＋. Pre-plant irrigation schedules can be made for semi-arid areas with the BEWAB＋ programme using easily obtainable inputs, like target yield, soil depth and soil particle size distribution information.
基金supported by the National Basic Research Program of China(Grant No.2007CB108902)the National Natural Science Foundation of China(Grant No.30771531)+2 种基金the Program for a New Century of Excellent Talents in the University(Grant No.NCET-08-0256)Fundamental Research Funds for the Central Universities(Grant No.lzujky-2012-k01)the Scholarship Award for Excellent Doctoral Student granted by Ministry of Education(Grant No.224000-860008)
文摘Various cadmium （Cd） concentrations （0, 50, 100, 200 and 300 μmol L-1） affected Elymus dahuricus seed germination, seed- ling growth, antioxidative enzymes activities （AEA）, and amounts of malondialdehyde （MDA） and proline present. These in- fluences were determined for separate E. dahuricus cohorts known to be either infected （E＋） or non-infected （E-） by a Neo- typhodium endophyte. Under high Cd concentrations （100, 200 and 300 lamol L-l）, E＋ specimens showed a significantly （P〈0.05） higher germination rate and index, as well as higher values for shoot length, root length and dry biomass. However, the germination rate and index, root length and dry weight did not show a significant （P〈0.05） difference under the low Cd concentrations （0 and 50 μmol L^-1）. AEA and proline content increased, as did MDA content, in the E＋ （vs. E-） specimens under high Cd concentrations. There was no significant （P〉0.05） difference under low Cd concentrations. Endophyte infection was concluded to be of benefit to E. dahuricus exposed to high Cd concentrations.
