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Wild diploid goatgrass, Aegilops tauschiiCoss., is the D-genome donor to hexaploid bread wheat. Goatgrass has been crossed with tetraploid durum wheat (Triticum turgidumvar. durumL.) and hexaploid bread wheat (T. aestivumL. ssp. aestivum) to broaden the genetic base of bread wheat. We examined the contribution of main stem water-soluble carbohydrates (WSC) and current assimilates to grain yield in one goatgrass relative to those in one durum and four cultivars of bread wheat under well-watered and droughted field conditions across two years. Drought reduced grain yield and its components. Number of tillers per plant was higher in goatgrass, but 55% of tillers produced were sterile. Number of grains per spike was lower in goatgrass. Grain weight was the component severely limiting potential yield in goatgrass. Main stem WSC and concentration was lowest in goatgrass. Linear rate of grain growth in goatgrass was 20 and 17 mg spike-1day-1under well-watered and droughted conditions, whereas those in durum and bread wheats ranged from 55 to 73 and from 37 to 60 mg spike-1day-1, respectively. Current assimilates were the major source of carbon to fill the grains under both irrigation regimes. A large number of goatgrass accessions and adapted durum cultivars should be examined for grain yield and its components to identify promising accessions to be used in producing synthetics.

The wild and weedy relatives of bread wheat, Triticum aestivumL., are suggested as potential sources of useful alleles for bread wheat improvement. For example, the genus AegilopsL. has contributed two of the three bread wheat genomes. In this study we measured the nature and extent of allozyme variation for 10 isozymes in three diploid and eight polyploid Aegilops, one Amblyopyrum(Jaub. & Spach), and one feral SecaleL. species collected from 15 populations in their centers of origin in Syria, Lebanon, Turkey, and California. The predominantly autogamous Aegilopsspecies were, to a large extent, homozygous and homogeneous. The presence of heterozygous genotypes in Aegilops tauschiiCoss. (H0= 0.0033 ± 0.01) and Ae. crassaBoiss (H0= 0.0048 ± 0.08) indicated the possibility of limited facultative outcrossing in these Aegilopsspecies. The obligate outcrossers, Amblyopyrum muticum(Boiss.) Eig (He= 0.09 ± 0.16) and Secale cerealeL. (He= 0.09 − 0.13), showed less than expected genetic variation. The extent and nature of genetic variation were identical between the introduced Californian Ae. cylindricaHost and that which occurs in the Fertile Crescent (He= 0.00); however, in Ae. triuncialisL., the introduced Californian population had a higher genetic diversity estimate (He= 0.06 ± 0.12) than the population from the Fertile Crescent (He= 0.00). The average genetic distance between the polyploid Aegilopsspecies was greater (D = 0.64 ± 0.28) than that observed between the diploid Aegilopsspecies (D = 0.18 ± 0.10), or between the diploid Aegilopsand weedy S. cereale(D = 0.52 ± 0.06). We discuss the implication of these findings for germplasm collection and wheat breeding.

Ninety‐three accessions of primitive domesticated diploid wheat (Triticum monococcumL.), five each of two wild tetraploid wheats (T. turgidumL. var. dicoccoidesKörn and T. timopheeviiZhuk. var. araraticumJakubz.), one cultivated durum wheat (T. turgidumL. var. durumDesf. ‘Modoc’) and one cultivated bread wheat (T. aestivumL. var. aestivum‘Anza’) were compared for plant height, seed weight, flour protein content, flour lysine content, lysine content in protein, spike weight, days to head, and days to flower under irrigated and dryland conditions in 1977. Superior lines were retested in 1979. Variation among lines for each trait in different species was significant except plant height in dicoccoides and araraticum. Over all species, plant height and seed weight were significantly higher, and protein and lysine contents were significantly lower in irrigated than in dryland conditions, although differences within dicoccoidesfor seed weight and protein and lysine contents were nonsignificant. Two accessions of monococcumwere short and headed and flowered as early as Modoc and Anza. Primitive and wild wheats were higher in protein content and lysine content but lower in spike weight and seed weight than the two modern cultivars. Wild tetraploids were higher in flour protein content and in flour lysine content but lower in lysine content in protein than monococcum. Accessions of dicoccoidesand araraticumhaving 30.9 and 30.5% protein, respectively, were identified. Correlations between traits were influenced by species and by moisture conditions. Best lines of monococcum, dicoccoides, and araraticumwere identified as sources of genes for different traits.

Resistance to root‐knot nematode, Meloidogyne incognita(Kofoid and white) Chitwood, has been identified and incorporated into commercial cultivars of common bean, Phaseolus vulgarisL. However, the effective use of host resistance as a management tactic against root‐knot nematodes attacking common bean requires identification and incorporation of resistance to other economically important root‐knot nematodes, namely M.javanica(Treub) Chitwood, M. arenariaand M. hapla. Fifty‐four common bean and 64 tepary bean, P. acutifoliusA. Gray, lines were screened for resistance to root‐knot nematodes under greenhouse and growth chamber conditions. In the greenhouse, the plants were grown in pots filled with loamy sand and, in the growth chamber, the plants were grown in growth pouches. Bean plants in the greehouse were inoculated with 5000 nematode eggs and evaluated for nematode reproduction (eggs) 6 wk after inoculation. In the growth chamber, plants were inoculated with 1000 second‐stage juveniles and evaluated for egg numbers 4 wk after inoculation. Common bean lines PI 165426 and Alabama no. 1 were found to be resistant to M. incognitaRace 2, 3 and 4 but were susceptible to M. incognitaRace 1 and to M. arenaria. Breeding lines A252, A315, A328, A443 and A445 were resistant to M. javanicaand M. incognitaRace 1. Resistance in the A lines was found to be derived from two common bean landraces, G1805 and G2618. The resistance was also effective against M. arenaria. The tepary bean accession PI 310606 was found to have good resistance to all nematode isolates tested. We postulate that resistance derived from G1805 and G2618 may be under different genetic control than that in PI 165426 and Alabama no. 1.