No abstract

The purpose of this research was to ascertain the genetic control of reproductive tiller production in orchardgrass (Dactylis glomerata L.) and to determine whether sparse panicle production affects.forage yield and quality. We postulated that sparse‐flowering synthetic would retain forage quality longer than normal cultivars as reproductive tillers mature in late spring and early summer. In the greenhouse, up to 12 weeks of cool, short days were required before some orchardgrass plants would flower under long‐day conditions. The response of progeny from three crosses to floral induction treatments suggested that a complex interaction of genetic and environmental factors controls the onset and rate of reproductive tiller production. Reciprocal differences were not observed. Syn 2 generation of synthetics, that produced relatively few flowering tillers when grown in the northeastern USA, flowered and produced satisfactory seed yields at Prosser, Wash.In the field under a hay management cutting system, the most sparse‐flowering synthetic had slightly lower first harvest forage yield in June. than the check cultivars, possibly because dry matter was produced rapidly by the flowering culms of the cultivars. The absence of significant differences among entries for in vitro dry matter disappearance or lignin concentration suggests that the synthetics and cultivars were similar in forage quality. Thus, the experimental strains exhibited no apparent improvement in forage production or quality.

Among nearly 4,000 spaced plants in a breeding nursery of orchardgrass, Dactylis glomerata, 9 remained nonflowering near University Park, Pa., during the growing seasons of 1959, 1960, and 1961. Experiments with floral inductive treatments of 8, 10, 13, and 16 weeks of short days at 10 C or below subdivided selected clones from this nursery into three groups. Three 4‐clone synthetics with different cold inductive floral requirements were formulated. First‐generation (Syn 1) seed produced in 1963 at Prosser, Wash., of Syn A, Syn B, and Syn C, averaged, respectively, 50 g, 21 g, and 32 g per clone. The Syn 1 generation was compared with ‘Pennlate’ in solid‐seeded field plots for production of panicles and forage in the Northeast. In June 1965 Pennlate, Syn A, Syn B, and Syn C produced, respectively, 12.6, 13.1, 4.1, and 1.7 panicles per square foot in Pennsylvania and 37.2, 4.3, 1.8, and 0.6 in Vermont These data indicated a genetic basis for the nonflowering characteristic.

Short‐duration growth chamber and field techniques are described for studying shade tolerance of pot‐grown seedling turfgrasses. Performance of eight selections each of bluegrass and red fescue grown at four light intensities from seed to 8 weeks in a growth chamber was evaluated. Varying light intensities were achieved by growing the grasses on shelves in a step‐like design so that the lowest light level was farthest from the illumination source. The four light levels in the growth chamber were measured at 3,000, 1,500, 500, and 230 ft‐c. A field study in natural deciduous shade which permitted entrance of approximately 5% of incident sunlight was used to concurrently evaluate 57 strains of Kentucky bluegrass, 1 lot of Canada bluegrass, 1 lot of roughstalk bluegrass, 18 strains of red fescue, 1 hard fescue, and 8 strains (including 3 species) of bentgrass. Both methods are feasible techniques for evaluating turfgrasses for shade tolerance. The field method has the advantage of concurrent evaluation of large numbers of turfgrasses under natural conditions. Performance of the red fescues in shade as a group was superior to that of the bluegrasses. ‘Golfrood’ red fescue was the outstanding cultivar and demonstrated superior shade tolerance in both the growth chamber and field.