Twenty-five female clones of Fragaria chiloensis (L.) Duchesene collected from the California and Oregon coasts were surveyed for gas exchange rates under field conditions. Carbon assimilation (A) rates of native clones were 25% to 69% higher than for `Totem' (Fragaria × ananassa Duchesne) on a leaf-area basis (μmol of CO2 per sec/m2) and 7% to 77% higher when expressed on a leaf dry-weight basis (μmol of CO2 per kg dry wt/sec). Higher rates of stomatal conductance (gs) were observed in 16 of 25 F. chiloensis clones than in `Totem', with nine of 25 clones also having higher rates of transpiration (E). All clones had higher rates of residual conductance (gr) and greater water use efficiency (WUE) than the cultivated standard. The gas exchange characteristics of four strawberry cultivars (F. × ananassa) and four F. chiloensis genotypes were compared under standard greenhouse conditions. F. chiloensis genotypes had higher rates of A than cultivars when expressed on per leaf-area and dry-weight bases. Native clones also had higher rates of gs, gr, E, and WUE and greater quantum yield. Differences in chlorophyll content were observed among genotypes, but not between species.
; Wilhelm and Sagen, 1974 ). Fragaria chiloensis is native to the fog belt along the Pacific Ocean from Alaska through British Columbia to the central California coast and as a disjunct distribution in Chile along the Pacific Ocean and into the Andes
Abbreviations: FC, Fragaria chiloensis Duch. cv. `BSP14'; FV, Fragaria virginiana Duch. cv. `NCC85-13V'; RWC, relative water content; TSC, total soluble carbohydrates; ψ water potential; ψ π osmotic potential; ψ π 100 osmotic potential at full
Abbreviations: FC, Fragaria chiloensis (L.) Duch. `BSP14'; FV, Fragaria virginiana (L.) Duch. `NCC85-13V'; RWC, relative water content; Ψ water potential; Ψ P , turgor potential; Ψ p osmotic potential; Ψπ 100 , osmotic potential at full turgor
The ‘Del Norte’ and ‘Yaquina’ clones of Fragaria chiloensis (L.) Duchesne exhibited a high degree of resistance to the strawberry aphid, Chaetosiphon fragaefolii (Cockerell), but a third clone, ‘OR-US 3162’, was very susceptible. Resistance of ‘Del Norte’ was transmitted to progeny when crossed with commercial strawberry cultivars, Fragaria × ananassa Duch. None of 30 commercial strawberry cultivars and advanced selections tested showed resistance to this aphid.
Thirty clones of the beach strawberry, Fragaria chiloensis (L.) Duch., that were known to be resistant to strawberry aphid, Chaetosiphon fragaefolii (Cockerell), were evaluated for resistance to twospotted spider mite, Tetranychus urticae Koch. AH clones had fewer mites per leaf than the cultivar ‘Totem’. Two clones, BSP-14 and LCM-19, had totals of only 6 and 82 mites, respectively, on 4 dates compared to 1741 mites on ‘Totem’. The ‘Del Norte’ clone of F. chiloensis, previously used as a source of aphid resistance in breeding, was more susceptible than BSP-14 and LCM-19 to the mite.
Plants of Fragaria chiloensis cv. RCP-37 were grown with their root system split between two separate containers. Water was withheld from one container of each pair (drought side), while the other was subirrigated. Control plants were subirrigated in both containers. Over several days, a drought-side leaf exhibited reductions in stomatal conductance (gs) and transpiration rate (T), while a subirrigated side leaf showed no change in either parameter. However, foliar water relations components (water, osmotic, and pressure potential) did not differ between the two leaves. The leaf on the subirrigated side exhibited gs, T, and water relations components similar to leaves on control plants. The abscisic acid (ABA) content of xylem exudate, collected from a stolon emerging from the axils of the measured leaves, was highest from the drought side and was negatively correlated to gs and T at some sampling dates. A root-derived drought stress signal, perhaps ABA, although other factors cannot be discounted, was limited within the plant to the drought side, even though water relations components indicated that water from the subirrigated side was allocated to all parts of the plant.
Fragaria chiloensis (Linnaeus) Is a viable. low maintenance alternative to groundcovers currently available in the ornamental landscape industry. There is considerable genetic variability within this specks for leaf morphology, growth and flowering habits as well as drought tolerance. Clones collected from 11 coastal sites in CA and OR were compared for drought tolerance after two Imposed water stress\recovery cycles. Predawn water potential, gas exchange, chlorophyll (chl) content, fourth derivative spectroscopy, carbon isotope discrimination, and total biomass production were evaluated and significant clonal differences were observed.
Predawn water potentials after the first stress cycle ranged from -35.0 MPa to -6.5 MPa. Clones I05, DNT and G19 had highest predawn water potentials and gas exchange rates after both stress cycles. In the control group, I05 and DNT had higher levels of chl a, chl b, total chl and chl a\b. After the first stress cycle, clones DNT and I05 had the highest chl a\b ratio, however, after the second stress event there were no differences In any chl parameters. Varying adaptive abilities observed may suggest differential use in the landscape.
staining solution). Table 1. Characteristics of six intersimple sequence repeat primers used for the analysis of Fragaria chiloensis accessions. Intersimple sequence repeat data analysis. From the ISSR patterns, each band was denoted
371 381 Cameron, J.S. Hartley, C.A. 1990 Gas exchange characteristics of Fragaria chiloensis genotypes HortScience 25 327 329 Dale, A. Sjulin, T.M. 1990 Few cytoplasms