A partial diallel design was used to investigate the inheritance of tolerance to terbacil herbicide in cultivated strawberry, Fragaria ×ananassa Duch. Two tolerant cultivars, `Honeoye' and `Earliglow', two moderately tolerant cultivars, `Lester' and `Allstar', and two susceptible cultivars, `Red Chief' and `Guardian' were used as parents to create populations that segregated for tolerance to the herbicide. Tolerance rankings of the populations closely coincided with expected rankings based on the published tolerance levels of parental cultivars. `Honeoye' and `Earliglow' derived populations had the highest average tolerance ratings, while `Guardian' derived populations had the lowest tolerance ratings. Heritability was estimated at h2 = 0.50, indicating that significant progress in increasing the tolerance of new cultivars to terbacil can be achieved through traditional recurrent selection procedures. General and specific combining abilities suggest that the tolerant cultivars in this study may be fixed in their tolerance and that increased mean tolerance will be most apparent in progenies combining tolerant and susceptible cultivars. As such, a broader pool of germplasm may be needed to develop cultivars that are more tolerant than those in this study. Chemical names: terbacil (3-tert-butyl-5-chloro-6-methyluracil)
Adequate weed control in the establishment year of matted-row strawberries (Fragaria × ananassa) is crucial for the long-term viability of plantings. Suppression of weed growth until the new strawberry plants are established and runners rooted is an effective strategy in new plantings. Three biodegradable mulch films were compared to standard weed control for establishing matted-row strawberries. Two films were test products using a biodegradable polymer, either clear or black, covering brown 40-lb kraft paper (IP40 Clear and IP40 Black, respectively). The third material was Planters paper, a black paper mulch. The films were evaluated for weed suppression, rate of degradation and effects on runner production and fruit yield. Additionally, the ability of runners that were formed to root as the film degraded was also observed. The IP40 Black mulch reduced the number of weeds compared to the standard control but did not degrade quickly enough for runners to root. The Planters paper also had fewer weeds, but it degraded quickly along the edges where it was covered by soil. This allowed the wind to tear it and blow large pieces off the plots. The IP40 Clear degraded in a timely manner and allowed runner rooting, but it was not acceptable as a weed suppression material. The IP40 Black and Planters paper mulches were effective for weed control in the establishment year, but rate of degradation was too slow in the former case and too fast in the latter. Runner production and fruit yield were not affected by any of the mulch materials compared to standard control.
Lack of variation among black raspberry cultivars is thought to be a limiting factor in fruit production and in breeding improved cultivars. An assessment of the available diversity in black raspberry is needed to effectively develop improved cultivars. Such an assessment was done to estimate the genetic similarities for RAPD markers in 16 black raspberry genotypes and to determine the genetic diversity among these genotypes based on these markers. In addition, the ability to distinguish between the black raspberry genotypes, two red raspberry cultivars (Rubus idaeus L.), and a blackberry cultivar (Rubus hybrid) was determined. A similarity matrix from 379 RAPD markers was calculated, and a phylogenetic tree was constructed using the PHYLIP suite of phylogeny software, which revealed the relationship among the genotypes. An average of 81% similarity was calculated among 16 black raspberry genotypes with a maximum similarity of 98% and a minimum of 70%. The average similarity between black raspberry and red raspberry was 41% and was 26% between black raspberry and blackberry. Combined marker profiles from six RAPD primers could be used to distinguish between the 16 black raspberry genotypes. Red raspberry and blackberry could be distinguished from black raspberry by 27 and 29 of 30 RAPD primers tested, respectively. Genetic diversity was most prominent in genotypes from the extremes of the black raspberry indigenous range. Diversifying the germplasm pool for black raspberry cultivar improvement can be achieved through utilizing genotypes from the extremes of the black raspberry range and through interspecific hybridization.
C.A. Weber, K.E. Maloney and J.C. Sanford
C.A. Weber, K.E. Maloney and J.C. Sanford
C.A. Weber, K.E. Maloney and J.C. Sanford
The performance of 11 primocane fruiting raspberry (Rubus idaeus) cultivars was evaluated based on yield and fruit weight from the first three seasons compared to the eighth and ninth seasons, respectively. Plot vigor and cane density was evaluated in the eighth season. `Prelude', `Caroline', and `Heritage' did not show a decline in yield in the eighth season compared to the first three seasons. `Kiwigold', `Graton Gold' (sold as `Goldie'), `Watson' (sold as `Ruby'), `Autumn Bliss', `Anne, and `Amity' had substantial yield decreases from early production seasons ranging from -30% to -82%. `Kiwigold' had the highest yield of 4015 kg·ha-1 (3582.2 lb/acre) in the eighth season followed by `Caroline' at 3649 kg·ha-1 (3255.6 lb/acre), `Heritage' at 3614 kg·ha-1 (3224.4 lb/acre), and `Prelude' at 3591 kg·ha-1 (3203.9 lb/acre). Fruit weight did not vary significantly among years, but there were differences among cultivars. In the ninth season, `Ruby' had the largest fruit at 3.1 g (0.11 oz), followed by `Autumn Bliss' at 2.9 g (0.10 oz), and `Caroline' and `Prelude' at 2.8 g (0.10 oz). `Summit', `Goldie', and `Rossana' had the smallest fruit at 1.5 g (0.05 oz). `Goldie' was the most vigorous cultivar and `Anne' the least in the eighth season based on vigor ratings. `Rossana' had the highest cane density at 41.6 canes/m2 (3.86 canes/ft2). Seven of 11 cultivars had cane density of 32 canes/m2 (3.0 canes/ft2) or higher, which is sufficient to produce acceptable yields in cultivars suited to the region. Overall, `Prelude', `Caroline' and `Heritage' and its sports, `Kiwigold' and `Goldie', show the most potential for long production cycles in climates similar to western New York state.
J.A. Pattison, W.F. Wilcox and C.A. Weber
A hydroponic method was developed and tested for screening red raspberry genotypes for resistance to Phytophthora fragariae var. rubi, the most common causal agent of Phytophthora root rot in raspberry. Plants of `Titan' and `Encore' exhibited typical disease symptoms, with the latter developing significantly smaller stem lesions and fewer petiole lesions. The resistant cultivar, `Latham', regenerated healthy root tissue from the crown and older-order roots after initial infection and necrosis of young roots and exhibited no other symptoms beyond minor leaf chlorosis. This component of the resistance reaction has not been documented previously. A segregating F1 population from the cross of `Latham' × `Titan' had a survival rate of 56% with 42% classified as resistant, exhibited minimal symptoms, and produced varying amounts of healthy root tissue. This screening method allows multiple observations of all plant tissues, including roots, under repeatable and definable growth chamber conditions. It should be useful for classifying the phenotype of individuals in segregating red raspberry populations to investigate the inheritance of Phytophthora root rot resistance using molecular markers.
C.A. Weber, W.B. Sherman and G.A. Moore
Segregating F2 peach populations in the Univ. of Florida breeding program were analyzed to determine linkage relationships among five qualitative traits: flower type, Sh/sh, flesh type, M/m; flesh color, Y/y; leaf gland type, E/e; and pubescence, G/g. Independent segregation was confirmed between flesh color and leaf gland type, between pubescence and flesh color, and between flower type and pubescence. Previously undocumented independent segregation was found between leaf gland type and flesh type and between pubescence and leaf gland type in our populations. The relationship between these latter characteristics should be investigated in other breeding populations. No correlation was found between fruit development period and flesh type. Also, no correlation was found between chilling requirement and flesh type.