The Size of the Root System of Lucerne Varieties Grown for Forage and Seed, and its Relation to Yield

The size of the root system as determined by its electrical capacity was evaluated in lucerne plants of two varieties and three new synthetic populations in field experiments during four years (1981–1987). The average size of the root system of plants which were harvested three times, per year for forage was about 11 % smaller than that of plants grown for forage in the primary growth and for seed in the secondary growth of each year. The smallest root system was determined in the variety ‘Bobrava’ and the synthetic population ZE-S-VH (relatively 100 and 100.9 %), followed by the variety ‘Palava’ and the synthetic population ZE-S-IV (1 05.1 anc 106.7 %). The largest root system was Sound in the synthetic population ZE-S-V (111.7%). One of the five parental Tories in ZE-S-IV and ZE-S-V exhibited significant effects of general combining ability for root system size. The large root system could also be due to higher resistance to vascular wilt. The larger root system is related to higher persistence, stability for more: cuts, higher level and stability of forage and seed yield in comparison to the control variety. The results present evidence for succesfully breeding, lucerne for larger root systems.     

Somaclonal variation for some morphological traits, herb yield, essential oil content and essential oil composition in an Indian cultivar of rose-scented geranium

Somaclonal variation for plant height, plant spread, leaf shape, leaf size, leaf form, herb yield, essential oil content and 10 important constituents of the essential oil was studied in an Indian cultivar, ‘Bourbon’ of rose‐scented geranium (Pelargonium graveolens). Significantly larger variance was observed among in vitro‐regenerated plants of the SC1 generation (first generation following an in vitro phase) than among parental plants raised from stem cuttings for herb yield, plant height, leaf size, essential oil content, and for the contents of cis‐rose oxide, trans‐rose oxide, isomenthone and 10‐epi‐γ‐eudesmol in the essential oil. Plants of the SC₁ generation showing values beyond the higher or lower limit (depending on the trait) of the range observed among parental plants for different traits were developed into clones by their multiplication through stem cuttings, and evaluated again in the SC₂ generation (second generation following the in vitro phase). Somaclones selected for plant spread, and for the contents of linalool and trans‐rose oxide in their essential oils did not breed true in the SC₂ generation. However, for the remaining traits studied, 13–100% of the selected clones retained their selected traits in the SC₂ generation, suggesting that the changes in these somaclones were due to genetic causes.     

Selection for Seed Yield Production of Egyptian Clover (Trifolium alexandrinum L.) C. V. Fahl

Modified mass and family selection for seed yield production of berseem clover (Trifolium alexandrinum L.) c.v. ‘Fahl’ were applied for two generations. Two hundred plants (5 % intensity of selection) were selected for seed yield in the first season, 1985/86. In the second season, 1986/87, selection between and within half-sib families was practiced. In addition, equal parts of seeds from each of the 200 selected plants were bulked to form the C₁ modified mass selection; after establishing, the same procedure was adopted to form the C₂ generation. The cycles 1 and 2 of half-sib families and modified mass selection along with the base population family were evaluated for forage and seed yields. The realized gains from modified mass selection were 6.03 and 9.51 % for fresh forage yield, 5.57 and 10.86 % for protein yield and 13.23 and 16.19 % for seed yield in cycles 1 and 2, respectively, over the base population. The realized gain from family selection in cycle 2 as a percentage of the base population mean amounted to 11.32, 13.35, 17.47 and 3.15% for forage, protein, and seed yield and seed index, respectively. The broad sense heritability, as estimated from the variance components was 89.63, 63.03, and 76.67 % for dry forage, seed yield and seed index, respectively. Although, all these five traits (fresh, dry, protein, and seed yield and seed index) had positive correlation with each other, weak correlations were found between seed yield and forage yields. Furthermore, close associations were found among forage yield traits.     

Stomatal Density and Length for Breeding of Evergreen Azaleas (Rhododendron simsii Planch.)

The hentability of stomatal density and stomatal length has been studied for four evergreen azalea (Rhododendron simsii Planch.) cultivars with the aim to evaluate the possibilities of stomatal characteristics of parental plants for increasing the crown diameter – hence yield – of the offspring., A nearly complete diallel cross with reciprocals has been carried out with the four parental cultivars. Highly significant general combining ability (GCA) values of the parents were found for stomatal length and density, but not for the crown diameter. GCA values of crown diameters did not correspond with GCA values of either stomatal length or stomatal density. Therefore it was concluded that utilizing stomatal characteristics as a selection tool for an increased crown diameter (yield) in azalea., may not be feasible. Differences in crown diameter could not be explained from correlations with either stomatal density or stomatal length.     

Prediction of indirect selection for seed and forage yield of lucerne based on evaluation under spaced planting

Phenotypic selection under spaced planting is frequently used in forage species. This study aimed to compare the predicted efficiency of direct selection for lucerne seed or forage yield under dense planting with indirect selection based on the same traits or seed yield components evaluated under spaced planting. Sixteen genotypes randomly chosen from a representative sample of locally adapted germplasm were grown for two years as individual clones spaced at 75 cm (density =1.78 plants/m²) and in dense plots formed by one row of four clones spaced at 10 cm (density = 50 plants/m²) using a randomized complete block design with three replications. Indirect selection based on seed yield under spaced planting was just 19% less efficient than direct selection, owing to moderate genetic correlation between plant densities (r_g = 0.66) and somewhat higher broad‐sense heritability under spaced planting than under dense planting. The relative efficiency of indirect selection for seed yield in density based on individual seed yield components under spaced planting ranged from modest to very low and was always below 45%. The efficiency of indirect selection for dry matter yield based on yield response under spaced planting was moderate for total yield (64%) and very low for second‐year yield (32%) relative to direct selection.     

A maternal factor conferring resistance to crown rust in Lolium multiflorum cv.'Axis'

The genetic basis for crown rust resistance was analysed in the progeny of reciprocal crosses between Lolium multiflorum plants that were either resistant (cv. ‘Axis’) or susceptible to crown rust. The progeny harvested from the resistant parent was two‐ to seven‐fold more resistant than the progeny harvested from the susceptible parent. These data indicate the presence of a maternal factor which increases resistance to crown rust in some of the ryegrass plants used as parents.     

Use of Isozyme-Marked Segments from Wild Barley (Hordeum spontaneum) in Barley Breeding

Fifty-six accessions of Hordeum spontaneum from various Israeli habitats were hybridized with, and their progeny backcrossed three times to H. vulgare cv. ‘Clipper’. Selected chromosome segments marked by one of 24 isozyme loci were transferred to form 84 backcross lines which were nearly isogenic with ‘Clipper’. Each line was made homozygous for a single isozyme-marked segment. These lines were evaluated in preliminary and advanced field trials. The yield, malt extract percentage and grain size of the lines approached or equalled, and sometimes significantly surpassed, that of ‘Clipper’ and more recent commercial cultivars. Three isozyme-marked segments were combined in pairs and the three resultant doubly-marked lines were compared with the reconstituted parental, singly-marked lines and with the ‘Clipper’ recombinant from the same F²-array. The additive effects of single segments on yield or gram size were not significant, whereas half of the six interactions were significant, but in the unfavorable direction. It was concluded that near-isogenic lines can identify segments of wild barley germplasm that are useful for improving yield, but that pairs of these from different habitats may interact unfavourably.     

Selection in Early Generations of Dried Peas, Pisum sativum L. II. Significance of the Environment of Selection

In early generations peas arc frequently grown widely-spaced against wire netting under growing conditions considerably different from the commercial cultivation practice of dense stands. In 1985 and 1986, five morphologically different pea varieties were grown both widely-spaced against wire and in dense stand in plots. In the plot stands no methods to prevent the peas from lodging were used. Grain yield and yield-related traits were recorded in both environments of selection, i.e. ‘wire netting’ and ‘plot stand’. Data were analyzed with respect to the suitibility of the environment ‘wire netting’ for selection for grain yield to be realized in commercial stands of the crop. Against wire, the grain yield, number of podded lateral branches, number of podded nodes/main stem, and the profile of grain yield/node on the main stem were the most responsive characters as compared to the standard plot with a dense stand. The relative increase differed between genotypes, which was also indicated by highly significant genotype × environment interactions. Only small changes consistent over genotypes were observed for thousand grain weight (slightly lower), number of seeds/pod (slightly increased) and grain yield/pod (slightly higher). Against wire, the expression of varietal variation was higher for most characters. In addition, single plant error was lower, so that at the wire heritability values based on individual plants were larger than in the plots. The significance of the present results and the effects of competition on selection in early generations in dried peas are discussed.     

内蒙古农牧交错区施氮量对燕麦饲草产量和饲用品质的影响

对比施氮量对饲草产量、品质的影响,为内蒙古农牧交错地区燕麦饲草增产提质提供理论依据。在旱作条件下对2个燕麦品种‘蒙燕1号’和‘8202’分别设低氮(30 kg/hm²)、中氮(90 kg/hm²)和高氮 (150 kg/hm²)3处理,比较其产量和品质。结果表明：施氮量显著影响2个燕麦品种饲草产量,‘蒙燕1号’在高氮处理下鲜、干产分别较其他处理增加8.42%~10.73%、9.30%~13.38%,显著高于低氮处理(P<0.05),且分别较‘8202’高氮处理下增产17.58%、19.28%。2品种粗蛋白、粗脂肪含量随施氮量的增加而提高。‘8202’粗蛋白含量在高氮处理下较其他处理提高4.24%~14.14%,较高氮处理下‘蒙燕1号’提高29.85%;‘8202’高氮处理下粗脂肪产量较其他处理提高0.44%~6.43%,较‘蒙燕1号’提高6.94%,2品种粗蛋白、粗脂肪含量在高氮、中氮处理下差异不显著,却与低氮处理差异显著(P<0.05)。施氮后品种间草产量和品质有差异,若以草产量为目标,应选‘蒙燕1号’,施高氮,可获鲜草40891 kg/hm²,可获干草7801 kg/hm²;若以品质为目标,应选‘8202’,施中氮,整株粗蛋白、粗脂肪含量分别可达17.66%,2.88%,可获粗蛋白1080 kg/hm²,粗脂肪166 kg/hm²。     

豫西地区青贮玉米光合和产量方面品种适应性研究

为了在豫西地区筛选到适宜的青贮玉米品种，以‘郑青3号’、‘京科932’、‘川单99’、‘郑单958’和‘雅玉8号’（对照处理）为材料，通过分析不同品种抽雄吐丝期的光合特性指标和荧光特性指标，结合最终鲜干草产量以及籽粒产量结果进行适应性分析。结果表明：‘郑单958’和‘川单99’表现较好的光合性能，‘川单99’表现出较好的叶绿素荧光性能且具有较高的鲜草产量，‘郑单958’具有较高的籽粒产量。因此，‘川单99’是豫西地区种植较为适宜的青贮玉米品种，‘郑单958’则是豫西地区收获籽粒和青贮饲料均适宜的兼用型玉米品种。     

Inheritance of morphological traits of periwinkle mutants with modified contents and yields of leaf and root alkaloids

Periwinkle Catharanthus roseus is a medicinally important plant producing anticancer and antihypertension alkaloids. Two mutants, one dwarf and one semidwarf and both, with a high alkaloid content in the roots and one mutant with a wavy leaf margin and a high alkaloid content in its leaves were obtained after induced chemical mutagenesis with ethyl methane sulphonate and N-nitroso-N-ethylurea in the variety ‘Nirmal’, which is resistant to dieback disease. These mutants were evaluated in the M₃ and M₄ generations. The dwarf and semidwarf mutants differed from the parental variety for many morphological characters, while the mutant with the wavy leaf margin differed mainly in leaf size and leaf thickness. Although both dwarf and semidwarf mutants showed a significantly higher alkaloid content in their roots in both generations, only the semidwarf mutant gave a significantly higher (23%) root alkaloid yield than the parental variety. The mutant with the wavy leaf margin showed a significantly higher alkaloid content in the leaves in both the M₃ and M₄ generations and also had a significantly higher (21%) leaf alkaloid yield than the parental variety. All three mutants were found to be controlled by monogenic recessive genes; the genes for ‘dwarfness’ and ‘semidwarfness’ were allelic to each other, with the allele for semidwarfness being dominant over the allele for dwarfness. The gene for the wavy leaf margin was inherited independently of the genes for dwarfness and semidwarfness.     

Oxidative stress indicators as selection tools for salt tolerance

Oxidative stress indicators, malondialdehyde (MDA) accumulation and chlorophyll retention, were tested as tools for salt‐tolerance screening in Chloris gayana (Kunth), a forage grass exhibiting inter‐ and intra‐cultivar variability in the response to salt stress. Three types of experimental system were compared, salt shock, gradual salt treatment and leaf segments floated on control and saline solutions. Results followed the same trend in the three systems, but leaf segments or gradually salinized plants are the most convenient. Lower mean MDA and higher mean chlorophyll content were found under salinity in cv. ‘Katambora’, which is considered, from previous field trials, to be more salt tolerant than cv. ‘Boma’. Nevertheless, chlorophyll content did not give consistent results in other tests and it is not recommended for selection purposes. Within cv. ‘Boma’, clones rating higher in a salt tolerance evaluation under greenhouse conditions had lower MDA content under salinity and lower mean MDA ratios between salt‐treated and control samples. The survival of 80‘Boma’ plants under increasing NaCl concentration was assessed and MDA was measured in the leaves of very plant before the final NaCl level was reached, to assess whether it was predictive of survival capability. MDA values were significantly lower in the group surviving longer, thus, a selection based on low MDA values would have enriched the original population with more tolerant individuals.     

长林系列油茶良种引种表现及评价

本研究于2010年引进油茶Camellia oleifera Abel.长林系列6个品种进行造林试验,全面评价了不同长林系油茶品种在常山县的性状表现。结果表明：油茶长林系列6个品种间在树体生长、果实性状、产量等方面都有着不同的表现。长林23号,长林166号和长林3号的冠幅较大,长林4号、长林40号、长林53号和长林23号的单位冠幅产量达到1 kg.m_-2以上,而且长林23号和长林40号的种仁含油率均达到44%以上。综合分析认为,长林4号、长林40号、长林53号、长林23号品种在试验地表现较好,应作为常山地区油茶发展的优先考虑品种。     

Potential use of doubled haploid lines for the screening of resistance to yellow rust (Puccinia striiformis) in hexaploid wheat

Doubled haploid lines derived from anther culture of two Iranian spring wheat genotypes‘Ghods’susceptible and‘9106’resistant to yellow rust in Iranian field conditions, and their F₁ hybrids were used in this study. Seedlings of 36 doubled haploid lines, selected out of 96 according to their agronomic traits and the two parental genotypes were inoculated with eight races of yellow rust. The parental genotypes (‘Ghods’and‘9106’) were segregating for some of the races but their doubled haploid lines were either resistant or susceptible to them.‘Ghods’was susceptible to three of the races studied but three doubled haploid lines derived from it were resistant to them. Five selected doubled haploids from the‘9106’genotype and six from F₁ hybrid plants were resistant to all eight races tested. After further investigations in Iranian field conditions it was found that some of these lines can be used as donor genotypes for resistance to yellow rust in wheat breeding programmes. Use of these genotypes should be possible if the French yellow rust races used for selection also represent the dominant races in Iran. It can be concluded that anther culture provides an efficient method for fixing genes of resistance to yellow rust and desirable doubled haploids from F₁ plants can be derived.     

Identification of a single dominant allele for resistance to blackleg in Brassica napus'Surpass 400'

The inheritance of resistance to blackleg (caused by Leptosphaeria maculans) was examined in the F1 and F2 of a cross between highly resistant canola ‘Surpass 400’ and susceptible ‘Westar’ in the field. Blackleg‐infected canola straw was collected from the field and scattered among plants to increase disease development with the aid of natural rainfall. Disease severity on seedlings was assessed as the average number of lesions on leaves 1 and 2, and on adult plants as the percentage necrosis on a cross‐section of stems immediately above the crown. All ‘Westar’ plants were susceptible (S) and all ‘Surpass 400’ and F1 plants were resistant (R) at both growth stages. Disease severity on F2 plants segregated 3 : 1 (R : S) as expected for a single dominant resistance allele in both the seedling and adult plant stages. There was a high proportion (91.1%) of matching reactions (R‐R and S‐S) between seedling and adult plants. ‘Surpass 400’ is the source of a single dominant allele for blackleg resistance in Brassica napus that is expressed strongly in both seedlings and adult plants.     

Durum Wheat under Mediterranean Conditions as Affected by Seed Size

This study was carried out in order to determine the effect of seed size on the growth and yield of durum wheat. Four field experiments, composed of six durum wheat (Triticum turgidum L. var. durum) varieties and three seeding sizes were conducted in north‐east Spain in 2000 and 2001 in randomized complete block designs. The growth of seedlings was dramatically affected by seed size. Large seeds produced greater plot stands, but the plants had fewer tillers, leaves and spikes and less green area and dry weight than plots from small seeds. Grain yield was 16 % greater in plots from large seeds, which resulted in greater biomass, green area index, spikes per m² and heavier kernels than in plots from small seeds. Kernel weight was the yield component most related to grain yield in the three seed sizes. The percentage of yield variation explained by kernel weight increased as the weight of kernels increased. This was a consequence of the use of larger seeds, the same effect being observed when the comparison was made between varieties with different kernel weights. Selection for heavy kernel varieties may help to improve the yield of durum wheat in Mediterranean environments similar to that prevailing in north‐east Spain.     

Recurrent Addition of the Pennisetum americanum Genome in a P. americanum×P. orientale Hybrid

An interspecific hybrid involving Pennisetum americanum (2 n = 14) and a diploid cytotype of P. orientale (2 n = 18) was backcrossed to P. americanum using the hybrid (2 n = 16, 7‘A’+ 9 ‘O’) as the female parent. Pollen mother cells of 13 BC₁ plants contained a complement of 14‘A’+ 9 ‘O’ chromosomes. Five BC₂ plants obtained through further backcrossing to P. americanum had 21‘A’+ 9 ‘O’ chromosomes revealing another addition of the P. americanum genome. The role of such recurrent additions of parental genomes in the evolution of polyploid species has been discussed.     

Genetic variability in herbage and seed yield in selected half-sib families of berseem clover, Trifolium alexandrinum L.

Berseem clover Trifolium alexandrinum L. is an annual forage legume commonly grown in pure stands and in grass mixtures in the Medi-terranean basin. Six populations were naturally cross-pollinated in 1990 and 1991 by a half-sib breeding method. In 1992 and 1993. 54 half-sib maternal plants, six original populations, and six advanced populations were field evaluated for forage (short cycle, harvest made at seven or eight inlernodes: long cycle, harvested at flowering) and seed yield (no forage harvest) in experiments at the Forage Crop Institute at Foggia, Italy (typical Mediterranean location). Genetic variability, narrow-sense herilability, genetic and phenotypic correlations among forage and seed yield component trails were investigated. The genetic variance in dry matter among maternal half-sib populations in short cycle was 51% greater than in long cycle. Narrow-sense heritabilily was 35% higher in short cycle than long cycle for dry matter and 26% higher for seed weight than seed yield. The magnitude of the genetic variance components and genetic correlations suggested that selection among plants of maternal half-sib populations would be more effective for improving dry matter in short than in long cycle harvests. The selection applied in the study was not effective for increasing seed yield per se however, the trait may be increased by selecting indirectly for seed weight.     

Condensed tannins in birdsfoot trefoil: Genetic relationships with forage yield and quality in NC-83 germplasm

Summary Genetic relationships of condensed tannins (CT) with other forage quality parameters have not been adequately studied in birdsfoot trefoil (Lotus corniculatus L.). The objectives were to bidirectionally select for CT concentration in birdsfoot trefoil to determine selection response and to create populations for examination of genetic relationships of CT with forage quality parameters, principally lignin. High-and low-tannin parental clones were selected from NC-83 birdsfoot trefoil germplasm and intercrossed to produce Syn₁ populations. Herbage samples, harvested for two years at two locations, were analyzed from high-tannin, low-tannin, and parental populations for CT concentration, herbage yield, and forage quality parameters. The mean condensed tannin concentrations in the high-and low-tannin populations were 69.3±0.8 and 21.1±0.8 g catechin equivalent (CE) kg^-1 dry matter (DM) compared with 36.4±0.8 g CE kg^-1 DM in the parental population. The selection response exhibited a quadratic relationship, with selection for increased CT concentration more effective than for reduced CT concentration. Compared with the parental population, acid detergent lignin (ADL) was higher, and crude protein (CP) and in vitro digestible dry matter (IVDDM) concentrations were lower for the high-tannin population and the converse was true for the low-tannin population. Lignin concentration was positively correlated with CT concentration (r_g=0.66 P0.01).Abbreviations ADF acid detergent fiber - ADL acid detergent lignin - CP crude protein - CT condensed tannins - IVDDM in vitro digestible dry matter - NDF neutral detergent fiber - NIRS near infrared reflectance spectroscopy     

高温干旱期203份苎麻饲用种质资源的农艺性状鉴定评价及高产优质种质筛选

为了筛选适宜南方高温干旱期生长的优质饲用苎麻种质资源,本研究对203份苎麻饲用种质资源的典型农艺性状以及粗蛋白质含量进行鉴定和评价。结果表明,该203份种质资源的茎粗、株高、小区株数、日均生长速度、茎业比、单蔸产量、粗蛋白质含量等7个农艺性状之间存在着不同的相关性。通过对比分析,筛选出高产种质资源（单蔸产量>1250 g/蔸）31份,优质种质资源（粗蛋白质>25%）32份,高产优质的苎麻饲用种质资源5份,分别为‘巫山线麻’、‘四川0号’、‘玉山麻’、‘绥宁青麻’以及‘邵阳青皮麻’。