Complete or incomplete dominance of resistance of the oat cultivar Delphin as a function of crown rust culture

Summary In oat cv. Delphin (Bonda x Carstens Vii) two complementary genes were found conferring resistance to sixteen cultures of ten crown rust (Puccinia coronata Cda. var. avenae Fraser ET Led.) races. The complementary genes showed full dominance to eight races and incomplete dominance to two races.     

Inheritance of groat-oil content and high-oil selection in oats (Avena sativa L.)

Summary The potential for breeding for high groat-oil content in oats was investigated by (a) conducting generation means analyses on data from three matings among adapted Avena sativa L. cultivars, (b) practicing one cycle of phenotypic recurrent selection in a segregating population derived from eight species backcrosses (Avena sativa x (A. sativa x A. sterilis)) among 24 parents, and (c) identifying transgressive segregates from interspecific (A. sativa x A. sterilis) matings.Additive gene action was the most important component in explaining the variation among generation means for groat-oil content. Dominance and epistatic interactions involving dominance were not significant in any mating. Significant residual genetic variation occurred in one mating, even after additive, dominance, and three digenic interactions were fitted. The importance of additive genes action implies that desired allelic combinations for high groat-oil content can be obtained in pure-line cultivars.One cycle of phenotypic recurrent selection using single plants as the selection units resulted in a genetic gain of 1.7 to 2.1% in groat-oil content. Individual plants selected for initiating the second cycle had from 9.5 to 12.6% groat oil.Over all 12 interspecific matings, the F₂ progeny means were similar to the midparent values. Only two were significantly deviant. Transgressive segregates for high and low groat-oil content from these matings provided evidence that A. sterilis possesses alleles for high and low groat-oil content that are different from those in the gene pool of cultivated oats.Journal Paper No. J-11340 of the Iowa Agric. and Home ECon. Exp. Stn., Ames, Iowa 50011. Project 2447. This study was supported in parts by grants from the Iowa Committee for Agricultural Development and the International Harvester Company.     

Domestication of the protein-rich tetraploid wild oats Avena magna and A. Murphyi

Summary The first stage in the domestication of the protein-rich tetraploid oats Avena magna and A. murphyi has been achieved by introducing seed non-shattering from the cultivated hexaploid oats A. sativa. A great variation in the protein content was encountered in the tetraploid domesticated types and plants having up to 27 31% protein were selected. The potential of these newly domesticated oats in increasing protein yields is briefly diseussed: also the significance of the tetraploids A magna and A. murphyi in improving the protein content of the hexaploid cultivars is stressed.     

Triple fusion of the primary endosperm nucleus as a cause of interspecific cross-incompatibility in Avena

Summary Using five diploid, two tetraploid and three hexaploid Avena species (x=7) 78 reciprocal crosses were made. Of these 74 were successfull, though the frequency of seed set varied greatly. The development of hybrid seeds differed widely between cross combinations, especially in reciprocal crosses. Hybrid seeds were grouped into four types, (1) normal kernels, well developed and germinative (designated as D+); (2) shrivelled-empty kernels, which do not germinate (E–); (3) small viable kernels (Rd+) and (4) small inviable kernels (Rd–). Some rare intermediate types were found in certain crosses.The results are well interpreted in terms of a hypothesis of polar-nuclei activation in which the strength of the activating action of the male nucleus, and the reaction of the female nucleus at double fertilization are expressed as activating value(AV) and response value(RV), respectively. The degree of seed failure is closely related to the activation index(AI) of the polar nuclei, AV/2RV (or × 100). In a selfed plant the activation index is always 1/2=0.5 (or50%), and this usually results in the formation of normal seeds. If AI deviates from 50% the endosperm often stops developing or degenerates.Based on the degree of abnormality of hybrid seeds, activating values of the ten species were arbitrarily assigned from 0.4 in A. ventricosa (2x) to 3.0 in A.sterilis (6x). For comparison A.strigosa (2x) was used as a standard and set at 1.0. Among the 74 succesful interspecific crosses the AI of the polar nuclei varied widely, from 7 to 375% Generally speaking, AI values of less than 20, 20–30, 30–80, and more than 80% show the R-, Rd+, D+ and E-kernel types, respectively. In other words, if the AV of the pollen parent is < 40 or >160% that of the maternal parent hybrid seeds fail to develop. Thus in double fertilization of Avena or probably angiosperms, the triple fusion of two polar nuclei with a secondary male nucleus is apparently a sexual isolation mechanism, being a barrier to interspecific hybridization.Professor Emeritus of Kyoto University, Faculty of Agriculture, Kyoto.     

Heritability of β-glucan, groat percentage, and crown rust resistance in two oat crosses

Summary Parent-offspring regression was used to estimate heritability for three traits (-glucan content, groat percentage, and resistance to crown rust (Puccinia coronata Cda. f. sp. avenae Eriks.) in oat (Avena sativa L.). The populations used were derived from two crosses, Nova x Marion QC and Sylva x Marion QC. Marion QC was used as a parent because other research had shown that it is relatively high in -glucan, a trait for which heritability had not previously been estimated. Nova and Sylva are similar in adaptation to Marion QC, and Sylva may be a source of general resistance to crown rust. Random F₅ plants were grown in a greenhouse, and their F₆ and F₇ progeny were grown in replicated field trials. Heritability estimates for the two grain quality traits were based on regression of F₆ values on F₅ values, F₇ values on F₆ values, and F₇ values on F₅ values. Heritability estimates for -glucan content were between 0.27 and 0.45. The highest estimate was the one based on the F₆ and F₇ generations of Sylva x Marion QC: 0.45, compared to estimates of 0.32 or less for earlier generations of the same cross, and to estimates of 0.35 or less for all generations of Nova x Marion QC. Heritability estimates for groat percentage were all between 0.23 and 0.32. The F₆ and F₇ generations were evaluated for resistance to crown rust resistance. The Sylva x Marion QC cross seemed to segregate for heritable resistance (h ²=0.31) but the Nova x Marion QC cross did not (h ²=0.07). Several lines from the Sylva x Marion QC cross had low symptoms in both the F₆ and F₇ generations. There were no strong genetic correlations among the traits.     

The genetics of naked oats (Avena nuda L.)

Summary The inheritance of the character complex of naked grain and multiflorous spikelets was studied in a diallel set of crosses comprising five varieties of naked oats (Avena nuda)-As 78, Manu, Caesar, Nuprime and AJ86/2/1-and one variety of husked oats (A. sativa), Maris Oberon. In the F₁ generation the distribution of multiflorous spikelets was in all cases similar to that of the mid-parent. Crosses between the varieties of A. nuda produced only naked grain on plants in the F₁ and F₂ generations, indicating that nakedness in the varieties studied was determined by the same loci.The three-gene model proposed by Moule (1972) for the determination of A. nuda characters was inadequate to account for the observed F₂ segregation in naked x husked crosses. An extension of this model is proposed to include a third modifying gene, N₃, which in the homozygous dominant condition produces the husked phenotype when the principal gene, N, is heterozygous. The model assumes complex epistatic relationships between the three modifying genes N₁, N₂ and N₃. Published information and further experimental data suggest that the genotype NN--N₃N₃ is uncommon. The expression of the genes determining nakedness was greatly influenced by the environment.     

海拔对不同燕麦品种产量及品质的影响

[目的]品种和海拔是影响燕麦草产量和品质的重要因素,高产品种可以提高干草产量20%以上,而且茎叶比也不同,产量越高,叶量越丰富,其干草产量和品质均高。所以,不断进行品种比较试验,引进新品种,对燕麦草生产的效益影响重大。[方法]试验研究了不同品种的燕麦在不同海拔地区的产量及品质的差异。[结果]经研究,青海444在甘南州不同海拔地区表现出良好的适应性,林纳和加燕2号在低海拔区产量较高,但在高海拔地区的产量不及本地燕麦。从茎叶比和营养物质含量分析,林纳和加燕2号的茎叶比较高,ADF和NDF的含量较低,因此,其品质好于青海444和本地燕麦。[结论]综合考虑燕麦草产量与品质2个因素,在甘南州低海拔地区适合推广林纳和加燕2号,高海拔地区适合种植本地燕麦和青海444。     

CA雄性不育性状在裸燕麦上的转育

用CA燕麦雄性不育材料与8个不同类型裸燕麦品种进行远缘杂交,对8个组合的F1,F2外稃性状的表现与分离进行了研究。结果表明,外稃性状F1穗型表现为既有皮型小穗又有裸型小穗的混合型,在F2外稃性状发生分离,分离比例为裸型∶混合型∶皮型=0.77∶2.16∶1.07。转育出4个不同类型的裸燕麦雄性不育材料,分别为Nms9602,Nms9606,Nms9801,Nms9804。     

Effects of Seeding Rate on Growth Duration and Accumulation and Partitioning of Dry matter in Oats

Crop management influences considerably the three components of grain yield, growth duration, growth rate, and harvest index (HI). Effects of seeding rate on these yield components in oats ( Avena sativa L.) was assessed in field experiments at the Viikki Experimental Farm, University of Helsinki, Finland (60°13'N) in 1991 and 1992. Three Finnish oat genotypes were evaluated; a long-strawed landrace cultivar, a moderately long-strawed modern cultivar, and a semi-dwarf breeding line. The following traits were measured: grain yield, days from sowing to yellow ripeness, number of tillers on main shoot, phytomass, vegetative phytomass, and their growth rates (PGR and VGR, respectively), panicle weight and its filling rate (PFR), HI, leaf area index (LAI), and at intervals, dry-matter accumulation in leaves and straw.
Increases in seeding rate significantly decreased growth duration and PGR of individual plants but increased PGR on a ground area basis. Seeding rate did not, however, affect HI. When seeding rate was increased from 200 seeds m⁻² to 500 seeds m⁻², reductions in vegetative phytomass, panicle weight, VGR, and PFR for individual plants ranged between 20 and 40 %, depending on genotype. At ≥600 seeds m⁻² differences in these components between seeding rates were modest. However, PGR, VGR, and PFR per unit ground area increased with increasing seeding rates up to 600–700 seeds m⁻². Moreover, the higher the seeding rate, the higher the peak LAI (2.7 maximum) and the earlier the canopy closure. Hence, our results showed that a seeding rate of 600–700 seeds m⁻², which resulted in uniculm growth habit, is advantageous in terms of grain yield at high latitudes due to higher biomass accumulation and subsequently greater interception of PAR.     

高寒区旱地莜麦合理种植密度的研究

通过对旱地莜麦不同种植密度的试验,进一步研究了密度对莜麦主要农艺状、干物质积累、叶面积系数及产量构成因素的影响,确定出在中等肥力条件下,晋北高寒区旱地莜麦的适宜种植密度为:播量600—675万粒/hm2,基本苗400—500万株/hm2。在该密度范围之内,群体和个体生长良好,产量各构成因素间关系协调,合理密植是获得旱地莜麦高产、稳产的关键技术。