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Inheritance of Potassium‐Sodium Nutritional Traits in Alfalfa
Author(s) -
James David W.,
Dhumal Suresh S.,
Rumbaugh Melvin D.,
Tindall Terry A.
Publication year - 1995
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1995.00021962008700040013x
Subject(s) - chlorosis , calcareous , heritability , biology , potassium , human fertilization , agronomy , shoot , horticulture , botany , chemistry , organic chemistry , genetics
Alfalfa ( Medicago sativa L.) growing on K‐depleted, semiarid, calcareous soil displays three K‐deficiency symptoms: (i) white spots on leaflets W, (ii) marginal chlorosis M, and (iii) normal leaflets on stunted plants (N). In a greenhouse study, we examined partitioning and heritability of K and Na nutritional traits in three alfalfa clones and their crosses, and also how K and Na soil fertility levels affected biomass production, genetic dependence of K and Na uptake and partitioning, and K use efficiency. Mother plants were propagated vegetatively and by seed from phenotype crosses in a low‐K, low‐Na, calcareous soil rooting medium. One trial used K‐ and Na‐amended soil. Harvests were at early bloom. Leaves contained more K than stems, with no difference among phenotypes; Na was uniform in stems, but leaves of M contained much more Na than leaves of N and W. With nonamended soil, K and Na uptake and partitioning among leaves, stems, and roots were significantly affected by cross. The Na:K ratio in leaves, stems, and roots was strongly influenced by phenotype and cross. Biomass production of leaves and stems differed among crosses and was increased by K fertilization; Na fertilization affected biomass only of leaves, and only in crosses M ✕ M and N ✕ N (Na may have partially replaced K). The shoot:root ratio was affected only by cross. Potassium use efficiency was affected by cross and by Na fertilization. Broad‐sense heritability for K and Na concentration was high, especially for Na in leaves and stems. Uptake and partitioning of Na and K in phenotype crosses supported narrow‐sense heritability as well. Genetics, rather than soil K‐Na competition, governed Na uptake, translocation, and utilization by phenotypes. Accordingly, characterization of K nutrition in alfalfa must consider Na levels. As phenotypes of alfalfa cultivars range widely in K‐Na nutritional traits, it should be possible to select for high yield and K use efficiency.