摘要:

Empirical and phenomenological models were used to analyze two sets of field data from the same location in Georgia. It was shown that cumulative dry matter production over the season followed a straight line on normal probability paper and that total annual yield exhibited linear dependence on harvest interval, both for intervals up to 6 weeks. The data were used to evaluate the three coefficients of the empirical model and the four coefficients of the phenomenological model. Auxiliary functions were used to relate all coefficients to applied nitrogen.

ISSN:0010-3624    

DOI:10.1080/00103629009368147

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Stems of barley and wheat plants of wide range in nutritional status were analysed for sap NO3concentration at the tillering stage using both “Merckoquant”; nitrate test strips and a specific‐ion nitrate electrode. Even though the “Merckoquanf'test strips used in this study did not give precise NO3readings they were found to be a satisfactory method for determining the NO3content of stems of cereals, and can be usedin situby farmers to predict the necessity of N fertilization for maximum grain yield. If the NO3sensitive area on the test strip is coloured to match the standard 500 ppm NO3colour in less than 30 seconds, after the application of sap, this is an indication of adequate N nutrition. If the 500 ppm NO3colour standard is reached between 30 to 60 seconds, then this is an indication of intermediate N nutrition and fertilization is recommended only under favorable weather conditions. If colour development of the test strip for the 500 ppm N03standard takes more than 60 seconds, or the colour developed does not reach this standard, this is an indication of deficient N nutrition. Therefore, the use of the “Merchoquant”; test strips offers a useful tool in deciding if N fertilization of small‐grain cereals is needed.

ISSN:0010-3624    

DOI:10.1080/00103629009368148

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103629009368136

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor