| Those entries that failed to head because of strong vernalization requirements
were not considered in this survey. At maturity five spikes were harvested
at random from each row. These spikes were then visually examined and one
representative spike was chosen for measurement of awn length and number
of spikelets per spike. Then all spikes were threshed en masse and
the total kernel number and weight was determined for calculating kernels
per spike and individual kernel weight. More details are given in SPAGNOLETTI
ZEULI & QUALSET (1986). For each character the entries with mean values at least 2.5 standard deviations (2.0 for awn length) higher than the world collection mean were identified. These entries are listed in Tables 1, 2, and 3 with their PI or CI number, their country of origin, and means and standard deviations for the whole collection. It must be considered that these results were obtained only in one location and in one year, that the environmental conditions were exceptionally favorable with high radiation, and that no temperature, water or nutrient stress occurred during the growing season. We could comment that we have used several of the accessions with very heavy kernels in the California breeding program and found that size was highly heritable (unpublished results). Request for seed stocks of these entries should be made to the National Small Grains Germplasm Collection, USDA-ARS, Aberdeen, Idaho, USA. Acknowledgements This work was made possible by grants from the California Crop Improvement Association, the International Board on Plant Genetic Resources and by a fellowship to P.L. Spagnoletti Zeuli from the Italian National Research Council. References JAIN, J.K., C.O. QUALSET, G.M. BHATT, & K.K. WU 1975. Geographical patterns of geographic variation in a world collection of durum wheats. Crop Sci. 15: 700-704. QUALSET, C.O. & Y.P. PURI 1974a. Heading time in a world collection of durum wheat: Latitudinal response and geographic origins relating to photo-and thermal-sensitivity. In G.T. Scarascia Mugnozza (ed): Proc. Intern. Symp. Genet. and Breed. of Durum Wheat. Bari (Italy): Univ. of Bari. pp. 165-178. QUALSET, C.O. & Y.P. PURI 1974b. Sources of earliness and winter habit in durum wheat. Wheat Inf. Serv. 38: 13-15. SPAGNOLETTI ZEULI, P.L. & C.O. QUALSET. 1987. Geographical diversity for quantitative spike characters in a world collection of durum wheat. Crop Sci. 27: 235-241. |
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