In sorghum [Sorghum bicolor (L.) Moench], genotype‐by‐environment interaction effects on ontogeny can be caused by differing responses to temperature and photoperiod. We conducted glasshouse and field experiments to develop predictive models of ontogeny for old and new sorghum genotypes. New genotypes are considered better adapted to more tropical environments. In the glasshouse studies, 10 genotypes were grown at two temperatures (20 and 25 °C) and six planting dates (photoperiod 10 to 15 h). At photoperiods greater than about 13 h, duration of emergence to floral initiation (GS1) was lengthened about 5 d for all genotypes at both temperatures. Genotypes differed in duration of GS1 by up to 10 d at both temperatures. Hybrids responded like their earlier parent, indicating earliness to show some form of dominance. Photoperiod had little or no effect on duration of floral initiation to anthesis (GS2), and hybrids differed by about 3 d. Field experiments with 12 hybrids were conducted at sites in Australia and USA covering latitudes from 16 to 39 °C. Durations of GS1 and GS2 ranged from 17 to 128 d and 24 to 85 d, respectively. Daily rate of development was modeled using functions of air temperature and photoperiod. Development rate of all hybrids exhibited a curvilinear response to temperature in both phases. Old and new hybrids differed in their temperature responses in GS1 but were similar in GS2. New hybrids had slower rates of development at all temperatures, but the difference was greater at higher temperatures (>25 °C). All hybrids had similar short‐day photoperiodic response in GS1, with a critical photoperiod 13.2 h. The models were tested on a separate data set covering a similar broad range of environments and performed well.

The germplasm base of strawberries is restricted. The major cultivated strawberry species, Fragaria ·ananassa, originated ' '250 years ago when South American F. chiloensis subsp. chiloensis forma chiloensis and North American F. virginiana subsp. virginiana accidentally hybridized in European gardens. Since that time, only a handful of native clones have been used by breeders. As a novel way to expand the germplasm base of the strawberry, we preselected native clones of F. virginiana and F. chiloensis for a wide range of horticulturally important characteristics and then reconstructed F. ·ananassa by crossing superior clones of each. Before crossing between species, we undertook one round of selection within species to maximize diversity. Reconstruction appeared to be an effective method of strawberry improvement, because superior families and individuals were identified that had outstanding vigor, high productivity, seed set, fruit color, and firmness. None of the fruit were of commercial size, but one reconstruction family, FVC 11 [(F. virginiana Frederick 9 · LH 50-4) · (F. chiloensis Scotts Creek · 2 MAR 1A)], had individuals with fruit weights of almost 20 g.

No abstract

Summary The genus Ribes L., known as currants and gooseberries, contains more than 150 diverse species indigenous throughout the northern hemisphere and along the Rocky Mountain, Sierra Nevada and Sierra Madres in North America through mountain ranges of Central America to the Andes in South America. Beginning in the 1400s, four main crop types, black currants (Ribes, subgenus: Ribes, section: Botrycarpum), red and white currants (Ribes, subgenus: Ribes, section: Ribes) and gooseberries (Ribes, subgenus: Grossularia) were domesticated from European species. American and Eurasian species were selected and combined into the germplasm base of European and American breeding programmes in the 1900s. Black currants (R. nigrum and hybrids) are a major economic crop in many European countries but are minor in North America, although they can be produced successfully in the northern states and southern portion of the Canadian provinces. Ribes plants can be hosts for white pine blister rust, caused by Cronartium ribicola. This disease was introduced from Asia through Europe into North America ca. 1900. Restrictions were imposed on currants and gooseberries in the United States when the rust was observed on this continent. Although some states have recently repealed these restrictions, by 2009, 12 states continue to have 40‐year‐old laws prohibiting or restricting Ribes cultivation. The purpose of this paper is to describe the cultivation of currants and gooseberries and their interaction with rust. Ribes production has a potentially great economic value in American, niche markets that could help sustain small‐acreage, berry farmers.

Pedigrees of 137 red raspberry (Rubus idaeus L.) varieties released throughout the world since 1960 were used to calculate: 1) the genetic contribution of founding clones to these varieties; 2) genetic relatedness among them; and 3) their inbreeding coefficients. Fifty founding clones contributed to the pedigrees of these varieties with a mean genetic contribution ranging from <0.1% to 21%. Varieties were clustered according to the genetic contribution into groups strongly related to geographical origin. Varieties developed in the former USSR and derived from `Novost Kuzmina' formed a distinct cluster. The remaining varieties were clustered in groups based mainly on whether they were of North American or European origin. Varieties were clustered also on the basis of Wright's coefficient of relationship-a measure of genetic relatedness. Cluster groups were related to their geographical origin and the varieties within the groups could be traced to similar intermediate parents. Inbreeding coefficients ranged from 0.0 to 0.625 and were related, in part, to the numbers of generations of controlled hybridization from common ancestors. The British group, with the largest number of generations of breeding, had a low mean inbreeding coefficient, indicating that inbreeding can be minimized with attention to the mating system. Strategies are suggested for maintaining and increasing the genetic diversity in the world's red raspberry breeding populations.