Files in this item
|(no description provided)|
|Title:||Leaf Lamina Reduced Nitrogen Concentration and Nitrate Reductase Activity as Criteria for the Identification of Productive Maize Genotypes|
|Author(s):||Messmer, Mark Jonathan|
|Department / Program:||Agronomy|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||Leaf lamina nitrate reductase activity (NRA), and total reduced nitrogen concentration (TRNC) in maize (Zea mays L.) were examined for relationships to grain yield, yield components, grain protein, maturity, and soil nitrogen fertility (N). Genotypes were classed as high and low for NRA (HNRA and LNRA respectively), and within those classes as high and low for TRNC (HTRNC and LTRNC respectively). The classification was valid for NRA and TRNC for the various genotypes. Increased grain yield was associated primarily with the HTRNC class, but to some extent with the LNRA class. Genotypes with combined LNRA and HTRNC classification were higher yielding and more stable over environments than any other NRA-TRNC class.
High TRNC genotypes had lower grain moisture at harvest, silked later, produced more and lighter kernels, and had a faster ear-fill rate after 5 weeks post-anthesis than LTRNC genotypes. At high soil N levels, HTRNC genotypes had a higher harvest index than the LTRNC genotypes.
High TRNC and LNRA genotypes produced more grain protein per hectare than LTRNC and HNRA genotypes. Classification of genotypes for NRA or TRNC had no effect on grain protein concentration.
Fertilizer nitrogen use efficiency (NUS) was examined in terms of the efficiency of plant accumulation of fertilizer N in leaf lamina tissue (NUP), and the utilization of accumulated leaf lamina reduced nitrogen to produce grain yield (NUT) and grain protein. Two levels of N fertility were examined in both 1981 and 1982. Differences among genotypic classes for NUP were not expressed. This was probably due to the inherent high fertility of the soil on which these experiments were grown. High TRNC and LNRA genotypes were more efficient in utilizing a given increment of accumulated leaf lamina reduced nitrogen to produce grain yield and grain protein than were LTRNC and HNRA genotypes. These NUT advantages resulted in NUS advantages for HTRNC and LNRA genotypes. This suggests classification of genotypes for high TRNC and/or low NRA may be useful for improving NUS in maize without direct measurement of grain yield.
Data suggests characterization of related genotypes for high TRNC and/or low NRA might be useful in combination with other agronomic traits for early culling of lines in a practical maize breeding program.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1983.
|Date Available in IDEALS:||2014-12-16|