Jeffrey J. Volenec, H. T. Nguyen, C. J. Nelson, D. A. Sleper1
1Former graduate research assistants, professor and associate professor, respectively, Dep. of Agronomy, Univ. of Missouri, Columbia, MO 65211.
Tóm tắt
High dark respiration rate (RD) may be a physiological process associated with low herbage yield of tall fescue (Festuca arundinacea Schreb.) during summer. Our objectives were to 1) examine genotypic variability and determine genetic mechanisms controlling RD and 2) examine interrelationships between RD, concentrations of Kjeldahl N and water‐soluble carbohydrate (WSC) of leaf blades, and yield components. Progeny of a seven‐parent diallel were grown and sampled in controlled‐environment chambers at 20°C and in the field during August and September. The RD was estimated manometrically on center‐sections of recently‐collared leaf blades. Concentrations of N and WSC were estimated on adjacent leaf blade tissue. Herbage was harvested, tillers per plant counted, and yield per tiller (YPT) calculated. Reciprocal effects evaluated in controlled‐environment chambers were not significant for any characteristic. Genetic variation among single‐cross progenies was significant for RD, leaf N, tillers per plant, and YPT largely due to general combining ability. Narrow‐sense heritabilities ranged from 0.60 to 0.90 which suggested that additive gene action predominated for these characteristics in this population. The RD was not correlated consistently with any characteristic measured. Concentrations of N and WSC of leaf blades were negatively correlated (r = −0.61). Positive rank correlations (P < 0.05) were obtained among progeny responses from controlled‐environment chambers and that of both field harvests for RD, tillers per plant, and YPT, and between field harvests for all variables (P < 0.01). Interrelationships among characteristics for parental plants were similar to those of the progeny. The similarity in ranking of RD of genotypes among controlled environment chambers and the field during summer and autumn suggests efficient identification of desired genotypes is probable over a range of environments.
