Premium
Variation Among Alfalfa Genotypes for Reduced Nitrogen Concentration 1
Author(s) -
Phillips Donald A,
Teuber Larry R.,
Jue Sally S.
Publication year - 1982
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1982.0011183x002200030042x
Subject(s) - biology , shoot , germplasm , dry matter , population , medicago sativa , kjeldahl method , medicago , horticulture , agronomy , dry weight , inoculation , botany , zoology , nitrogen , chemistry , biochemistry , demography , organic chemistry , sociology , gene
Kjeldahl N concentration was measured in ‘African’ and ‘Hairy Peruvian’ germplasm sources of alfalfa ( Medicago sativa L.) grown first with N 2 and then with 8 m M NH 4 NO 3 to assess variation in shoot protein content for possible improvement of alfalfa quality. Shoot N concentration was determined on 120 seedlings from each germplasm source grown without combined N and inoculated with Rhizobium meliloti Dang. strain 102F28. Each plant shoot was harvested when the first flower opened during three successive growth cycles. After the second harvest following growth on N 2 , plants again were grown to flowering with 8 m M NH 4 NO 3 , and no significant contribution to N content was detected by the C 2 H 2 ‐reduction assay. Although herbage dry weight and percent N generally were correlated negatively, it was possible to select two groups of plants from each germplasm source: I) high percent N in shoots on both sources with dry matter production near the average of the unselected population, and II) low percent N in shoots on both N sources with dry matter production near the average of the unselected population. Herbage of plants selected for high percent N averaged 13 to 16 % greater crude protein concentration on the two N sources than the original population and 30 to 35 % greater crude protein concentration than seedlings selected for low percent N. Ramets established from three seedlings within each selected population were tested separately for percent N content on each N source in two trials. All ramets within a N treatment produced similar herbage yield, and genotypes selected for high percent N had significantly higher shoot N concentration on both N sources than genotypes selected for low percent N. The results show that when N nutrition is controlled carefully by separating combined N and Rhizobium effects, a small percentage of alfalfa genotypes with superior crude protein content and normal dry matter production can be identified.