Comparison of pod calcium concentration between two snap bean populations

To understand the genetics that control pod Ca concentration in snap beans, two snap bean (Phaseolus vulgaris L.) populations consisting of 60 genotyp es, plus 4 commercial cultivars used as checks, were evaluated during Summe rs 1995 and 1996 at Hancock, Wis. These populations were CA2 ('Evergreen' x 'Top Crop') and CA3 ('Evergreen' x 'Slimgreen'). The experimental design w as an 8 x 8 double lattice repeated each year. No Ca was added to the plant s grown in a sandy loam soil with 1% organic matter and an average of 540 p pm Ca. To ensure proper comparison for pod Ca concentration among cultivars , only commercial sieve size no. 4 pods (a premium grade, 8.3 to 9.5 mm in diameter) were sampled and used for Ca extractions. After Ca was extracted, readings for Ca concentration were done via atomic absorption spectrophoto metry. Ln both populations, genotypes and years differed for pod Ca concent ration (P = 0.001). Several snap bean genotypes showed pod Ca concentration s higher than the best of the checks. Overall mean pod Ca concentration ran ged from a low of 3.82 to a high of 6.80 mg . g(-1) dry weight. No differen ces were detected between the populations. Significant year x genotype inte raction was observed in CA2 (P = 0.1), but was not present in CA3. Populati on variances proved to be homogeneous. Heritability for pod Ca concentratio n ranged from 0.48 (CA2) to 0.50 (CA3), Evidently enhancement of pod Ca con centration in beans can successfully be accomplished through plant breeding .