| II. Genetic Stock Germplasm resources in durum wheat: Extreme variants for some quantitative spike characters in the USDA world collection P.L. SPAGNOLETTI ZEULI1, C.O. QUALSET, and D.H. SMITH2 Department of Agronomy and Range Science, University of California, Davis, USA Most of the world collection of durum wheat (Triticum turgidum L. durum group) of the U.S. Department of Agriculture was systematically surveyed in a field planting at Tulelake, California in 1970. The variation observed for heading time was reported and a listing of the accessions having earliness and winter habit was reported (QUALSET & PURI 1974a, b). In addition, the amount of variation in this collection was estimated using qualitative characters of the spike, such as glume and awn color, kernel color, and glume pubescence. The measure of diversity at local and regional levels provides useful information to germplasm conservationists and plant breeders (JAlN et al. 1975). Data for some quantitative characters in the spike were collected at the same time. These were recently analyzed to illustrate how multivariate statistical analysis can be used to describe variation and patterns of variation among ecogeographic regions. The analysis provides a basis for plant breeders to select parental lines from a large collection. We have suggested that this multivariate approach be used to identify highly diverse genotypes to broaden the genetic base of durum wheat breeding programs (SPAGNOLETTI ZEULI & QUALSET 1986). Genetic improvement in grain yielding potential is a major objective in durum wheat. This improvement must be expressed in one or more yield components, and since the spike contributes two of the three end-point yield components, there is obvious interest in identifyilng genetic resources for these characters. We present herein a list of entries of the USDA World Collection of durum wheat that have interesting spike characteristics that might be useful in breeding programs. About 3500 durum wheat entries were planted at Tulelake, California (41o58' N Iatitude, 121o28' Iongitude; 1240 m elevation) in April 1970. The crop was mature about 10 September. A single 2-m row, with rows spaced 60 cm apart was grown for each entry. Sentry and Oviachic 65 durum cultivars were grown periodically throughout the planting for comparisons. |
| 1. Institute of Agricultural Biology, Potenza, Italy. 2. U.S. Department of Agriculture, Agricultural Research Service, Beltsville, MD 10705, U.S.A. |
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