Use of a micro-sward technique for determining bite mass of four grass species in short-term tests

Four grass species typically found in semi-natural pastures in the UK were sown individually in boxes (85 × 44 × 14 cm) to create micro-swards. Yorkshire fog (Holcus lanatus L.); creeping bent (Agrostis stolonifera L. cv Kromi); rough meadow-grass (Poa trivialis L.); and perennial ryegrass (Lolium perenne L. cv Glen) were offered to yearling Simmental × Holstein steers in short-term tests to characterize bite mass in relation to morphological traits of the grass species. Boxes were weighed (±0.1 g) before and after a 5 min period during which the steers were allowed to take ~50 bites. Perennial ryegrass had the greatest sward surface height (17.7 cm vs. mean 12.7 cm for the other species). Extended tiller length was greatest for ryegrass (17.3 cm) and least for rough meadow-grass (13.5 cm). Leaf length was greatest for ryegrass (6.5 cm) and Yorkshire fog (7.0 cm) and least for creeping bent (4.0 cm). Sward DM% was lowest for ryegrass (19.7%) and highest for creeping bent and rough meadow-grass (mean 23.2%). Number of bites taken from the boxes did not differ between grass species (mean 32.7 bites). Mean dry matter bite mass was greatest for perennial ryegrass (0.50 vs. mean 0.37 g DM bite⁻¹ for the other species). Regression analyses indicated that the best sward variables for predicting mean DM bite mass were sward DM% (F prob. = 0.066) and sward surface height (F prob. = 0.086). While morphological characteristics affected bite mass, more is yet to be learned about other factors that may affect intake characteristics of forage species to improve economic and environmental sustainability.     

Resynthesizing <Emphasis Type="Italic">Brassica napus</Emphasis> from interspecific hybridization between <Emphasis Type="Italic">Brassica rapa</Emphasis> and <Emphasis Type="Italic">B. oleracea</Emphasis> through ovary culture

Using three varieties of Brassica rapa, cv. Hauarad (accession 708), cv. Maoshan-3 (714) and cv. Youbai (715), as the maternal plants and one variety of B. oleracea cv. Jingfeng-1 (6012) as the paternal plant, crosses were made to produce interspecific hybrids through ovary culture techniques. A better response of seed formation was observed when ovaries were cultured in vitro at 9–12 days after pollination on the basal MS and B5 media supplemented with 6-benzylaminopurine (BA) and naphthylacetic acid (NAA). The best response was observed for cross 714×6012 with the rate of seeds per ovary reaching 43.0%. Seeds for cross 715×6012 showed the best germination response (66.7%) on the regeneration medium (MS+1.0 mg l^–1 BA+0.05 mg l^–1 NAA). In all three cross combinations, good response in terms of root number and length of plants was observed on the root induction medium (MS+1.0 mg l^–1 BA+0.1 mg l^–1 NAA). A better response was observed for the regenerated plants cultured for 14 days than for 7 days. The ovary-derived plants with well-developed root system were hardened for 8 days and their survival rate reached over 80%. Cytological studies showed that the chromosome number of all plants tested was 19 (the sum of both parents), indicating that these regenerated plants were all true hybrids of B. rapa (n = 10) × B. oleracea (n = 9). The regenerated plants were doubled with colchicine treatment, and the best response in the crosses 708×6012, 714×6012 and 715×6012 was observed when treated with 170 mg l^–1 colchicine for up to 30 h and their doubling frequency reached 52, 56 and 62%, respectively.     

Plant damage after freezing, and the frost resistance of varieties from the facultative and winter wheat observation nurseries

In the first experiments, studies were made on the survival % of fourwinter wheat varieties with good frost resistance and two with poor frostresistance, and on the degree of plant damage after freezing at –14 ^°C and –16 ^°C under phytotron conditions. In the secondexperiment the frost resistance of the varieties included in the 9^thFacultative and Winter Wheat Observation Nurseries (FAWWON) wasdetermined after freezing in the phytotron at – 15 ^°C. The scoresgave a good reflection of the variety ranking determined on the basis ofsurvival % and of the different effects of the two freezing temperatures. Onthe basis of the scores, the plants were divided into two groups for eachtreatment and each variety: plants which suffered frost damage (a score of2–3), and plants which suffered no frost damage (a score of 4–5).Twenty plants from each group were raised to maturity in pots. Theyield parameters of plants damaged by freezing at – 14 ^°C werereduced to a lesser extent than those frozen at –16 ^°C. Of the eightparameters tested, the reduction in the number of ears per plant andconsequently in the number of grains in the side ears, the grain mass andthe total grain yield, gave the clearest indication of the extent of plantdamage. The results of the second experiment indicated that in some casesthe frost resistance of the varieties could be predicted from the wheatproduction zone (e.g. varieties from Eastern Europe and Nebraska haveexcellent frost resistance), while in other zones winter hardiness and frostresistance depended rather on the country or on the breeding location.     

Genetic improvement of soybean varieties released in India from 1969 to 1993

Summary Soybean is an important oilseed crop in India and varieties with high yield potential are being developed since 1969. This study was conducted to assess the impact of breeding on yield and plant characteristics during the last 25 years. A 3-year field experiment was conducted to evaluate forty three soybean varieties belonging to two different selection cycles and representing most of the varieties developed in the domestic breeding programme of India from 1969 to 1993. Varieties resulting from selection cycle 1 showed 4 times higher seed yield and harvest index as compared to the farm traditional variety Kalitur. This yield increase was due to an increase in biomass, pods plant^–1, mean seed weight and longer seed filling duration, but a reduced plant height and improved lodging tolerance, less seeds pod^–1 and early flowering and maturity dates. The varieties of selection cycle 2 showed 19% higher seed yields and 16% increase in harvest index over selection cycle 1 accompanied by longer seed filling duration, more seeds pod^–1 and reduced plant height. The annual genetic gain in seed yield of soybean varieties released in India from 1969 to 1993 was approximately 22 kg ha^–1.     

Response of white clover genotypes to evaluation environments of dense and spaced planting, and implications for selection

Twelve genotypes were grown for two years asmonocultures in the evaluation environments (EE) ofspaced planting (SP) and dense planting (DP). Drymatter (DM) yield, seed yield and their contributingtraits were recorded. The environments were comparedfor: i) genotype performance, and selection efficiencyfor the target environment of DP, and ii) estimates ofgenetic correlations between traits. DP was obtainedby close transplanting of clonal cuttings. EE × Ginteraction occurred for DM yield over harvests, andstolon density, petiole length, inflorescenceproduction and number of florets per inflorescence averagedover repeated measurements. Interaction effectsleading to relatively higher DM yield in SP tended tobe associated positively with those for the othertraits and featured the genotypes with greater abilityto colonize bare soil by stolon production. Theinteraction effects decreased with time and generallydisappeared (p < 0.05) by the end of the experiment,when the environments reached a similar DM yield andstolon density. EE × G interaction also occurred forseed yield (p < 0.08), recorded at the second year.Indirect selection in SP for performance in DP waspredicted to be less efficient for DM yield (–40%),seed yield (–23%) and the other traits subject to EE ×G interaction, compared with direct selection in DP.Evaluation under SP led to identification of severalgenetic correlations that were not confirmed under DP.DP compared with the traditional SP evaluationtechnique is more labour-demanding but allows for i)increasing the selection efficiency and/or decreasingthe time needed for a reliable evaluation, and ii)obtaining a more reliable estimation of geneticcorrelations for ordinary agricultural environments.     

Improvement of flue-cured tobacco by means of ionising radiation

Three commercial varieties of flue-cured tobacco viz., Chatham, Delcrest and Hicks were subjected to neutron irradiation using six different doses ranging from 1×10¹² to 5×10¹³ N/cm²/sec. The N₁ generation was grown in the field during 1959–60. Only plants from the lowest two doses viz., 1×10¹² and 2.5×10¹² N/cm²/sec. survived in the field up to the adult stage. From this material, normal plants with high pollen fertility were selected for testing their performance in replicated trials.The progenies of the selected plants were raised in the field during 1960–61. The data collected showed that although there were no significant differences in the means in some characters there was a significant shift in the variance among treated plants as compared to the control. Advantage was taken of this greater variance among the treated progenies and selections were made for certain specific characters viz. narrow leaf and long internodes in Chatham, broader leaf, late flowering and greater leaf number in Delcrest and Hicks.A new leaf mutant in the variety Delcrest was isolated which was found to be agronomically superior to the untreated control. This mutant is characterised by hooding of the leaf tip and is designated leaf tip hooded.Replicated trials were conducted for the narrow leaf and long internoded types in Chatham, the leaf tip hooded in Delcrest and the late flowering selections in Hicks, during 1962–63. The narrow leaf selection in Chatham bred true. The long internode type was found to be segregating. The leaf tip hooded mutant in Delcrest was found to breed true and has also maintained its superior performance.The achievements and scope of the mutation breeding programme in flue-cured tobacco have been broadly discussed.     

Chemical Composition and Ruminal Dry Matter and Crude Protein Degradability of Spineless Cactus

The objective of this study was to determine ruminal degradability of the dry matter (DM) and crude protein (CP) of 10 varieties of spineless cactus (Opuntia spp.) grown in north‐eastern Brazil. Two ruminally fistulated steers were used in a randomized complete block design. Ash, CP, acid detergent fiber, and acid detergent lignin levels ranged from 10.4 to 13.3 %, 6.2–7.7 %, 19.8–24.8 % and 3.4–5.4 %, respectively. Relative to the other cactus varieties, Redonda had the highest (P < 0.05) in situ soluble DM fraction and effective DM degradability. No differences in effective DM degradability were observed between the other cactus varieties. In situ soluble CP fraction ranged from 1.7 % of CP for the 69 IPA/UFRPE variety to 11.1 % of CP for the Gigante variety. Slowly degradable CP fraction and its rate of degradation were similar among the cactus varieties (average 90 % of CP and 9 % h^?1, respectively). The cactus variety 69 IP/UFRPE had a lower (P < 0.05) effective ruminal CP degradability (ECPD) than the other varieties, which had a similar ECPD (average 66 % of CP). It was concluded that differences in ruminal degradability exist between cactus varieties, with more variations observed for ruminal DM than for CP degradability.     

Associations and genetics of three components of slow rusting in leaf rust of wheat

Summary Forty F₆ lines, the two parental lines, and a susceptible check cultivar of wheat (Triticum aestivum L.) were inoculated in the young flag leaf stage with leaf rust (Puccinia recondita f.sp. tritici) and evaluated for latent period, receptivity, and uredinium size in a greenhouse experiment. Genotypic (r_g) and phenotypic (r_p) correlations between latent period and uredinium size were –0.81 and –0.62, respectively. A negative correlation (r_g=–0.50, r_p=–0.41) was found between latent period and receptivity and a positive correlation (r_g=0.28, r_p=0.26) between uredinium size and receptivity was found. Area under the disease progress curve (AUDPC) and final rust severity (FRS) obtained from a subsequent field study with common entries were negatively correlated with latent period and positively correlated with uredinium size. Correlations of receptivity with both AUDPC and FRS were not significant. The distributions of F₆ family mean uredinia size and latent period were continuous between slow rusting and fast rusting parents: however, the distribution for receptivity was discrete. Narrow-sense heritability estimates were 63%, 57%, and 47% for uredinium size, latent period, and receptivity, respectively. Estimates of the minimum number of effective factors were three for latent period and three or four for the uredinium size and receptivity. The components are controlled by closely linked genes or due to pleotropic effects of the same gene.Abbeviations AUDPC - Area under the disease progress curve - FRS - Final rust severity     

Production of intergeneric hybrid plants between <Emphasis Type="Italic">Sandersonia aurantiaca</Emphasis> and <Emphasis Type="Italic">Gloriosa rothschildiana</Emphasis> via ovule culture (Colchicaceae)

Intergeneric hybrid plants between Colchicaceous ornamental plants, Sandersonia aurantiaca and Gloriosa rothschildiana, have successfully been produced via ovule culture. After 5 days of reciprocal cross-pollination, a few pollen tubes were observed in the ovary. Although seeds were obtained in both reciprocal cross-combinations, they did not germinate under ex vitro conditions. Ovules with placental tissues isolated 14 days after cross-pollination of S. aurantiaca × G. rothschildiana were cultured on a medium containing 0.01 mg l^–1 each of -naphthaleneacetic acid (NAA) and 6-benzyladenine (BA), on which 41.5% of ovules swollen and produced callus-like structures within 10 weeks. When such swollen ovules were transferred to a medium containing 0.1 mg l^–1 each of NAA and BA, 7.5% of the initially cultured ovules produced rhizome-like structures within 6 weeks. Among the rhizome-like structures, those derived from two independent ovules (3.7% of the initially cultured ovules) produced multiple shoots following transfer to a medium containing 0.25 mg l^–1 NAA and 2.5 mg l^–1 BA. Multiple shoot-derived plantlets were established on a plant growth regulator-free medium, and they were successfully transplanted to pots. Early verification of their hybridity was accomplished by flow cytometry (FCM) analysis, chromosome observation and rDNA analysis.     

Sources of resistance in wheat to speckled leaf blotch caused by Septoria tritici

Summary Seven and a half thousand wheat varieties, including over 2,000 durums, were screened for resistance to Septoria tritici under conditions of artificial inoculation in the field. From this screening, 460 varieties were selected on the basis of resistance and earliness and were subject to more detailed observation.Selected varieties were tested in the field with two replications under both natural and artificial epidemic conditions. The agreement between varietal scores in the two replications and under the two conditions was good; 91–94% of varieties showing consistent disease scores. The correlation coefficient between varietal scores for the natural epidemic and the artificial epidemic conditions was 0.63^***.A number of the very early maturing varieties of T. aestivum showed good resistance as measured by pycnidial production but exhibited extensive leaf necrosis. This reaction was not observed in later varieties and in accessions of T. durum.Varieties of Triticum durum were typically more resistant than varieties of T. aestivum. Thirty-four varieties of T. aestivum and 266 varieties of t. durum showed a consistent expression of resistance. A list of these 34 accessions of T. aestivum and selected accessions of T. durum is provided, along with agronomic data.     

Selection for early flowering in progenies of interspecific crosses of ten species in the genus Dianthus

Summary Twenty-seven progenies of interspecific crosses, involving ten Dianthus spieces (D. caryophyllus, D. chinensis, D. superbus, D. barbatus, D. japonicus, D. brachyzonus, D. versicolor, D. trifasciculatus, D. serotinus and D. knappii) and some complex interspecific hybrids (Diantini genotypes and D. Allwoodii selections) were grown from seed under 8 hr days at two light intensities: 12 W/m² and 22 W/m². Observations on individual plants were made on vegetative development and date of flowering. After six months, 178 plants were selected from 23 seedling progenies and the resulting clones were compared under 22 W/m² and two photoperiods: 8 hrs and 24 hrs per day for a period of nearly six months. In the seedling stage, large differences were observed between progenies, e.g. in percentage generative plants (0–100%), plant length (3–78 cm) and plant fresh weight (0.5–68 g). Effects of light intensity were most pronounced in plant fresh weight (0.2–18 g in 12 W/m² and 0.5–68 g in 22 W/m²). Progenies of D. chinensis were the earliest to flower. Most progenies of crosses between D. superbus and D. barbatus segregated into flowering and non-flowering (rosetting) plants. In the clonal stage, most clones originating from non-flowering seedlings remained vegetative (rosetting), while all clones from flowering seedlings were either in flower or in bud within six months. Average dates of flowering of seedling progenies and of their clones were highly correlated, suggesting that selection on flowering date at the seedling stage is effective. High correlations were also found between the average flowering date of seedling progenies and the number and total weight of flowers harvested per plant in their clones within six months from planting. Overall effects of LD in the clonal stage were much less spectacular than the effects of light intensity in the seedling stage.     

The crossability percentages of 96 bread wheat landraces and cultivars from Japan with rye

Summary Crossability of bread wheat (Triticum aestivum L.) from Japan with rye (Secale cereale L.) was investigated by controlled pollination. No normal seeds were produced, but numbers of shrivelled and small seeds with embryos were used to estimate crossability amongst the 96 accessions, viz: 0–10% (29), 10–30% (23), 30–50% (11), 50–90% (33). The investigation for the pedigrees of varieties with more than 50% crossability percentages showed that the kr alleles of some accessions derived from common ancestors.     

The Effect of Sward Management on the Mineral Content of Winter Grazed Herbage

No information is available regarding the mineral content of autumn‐saved herbage during winter grazing under Central European conditions. Therefore, P, K, Na, Mg and Ca concentrations of autumn‐saved growths of Festuca arundinacea and Lolium perenne were analysed considering the potential influence of pre‐utilization (saved from June or July), date of winter harvest (December, January, February) and year (three winters). For all years date of winter harvest was the main source of variance, whereas date of preceding cut had no relevant effect on the mineral concentrations during winter. Already in December P [2.3 to 4.0 g kg^?1 dry matter (DM)], Na (0.3 to 3 g kg^?1 DM) and Mg (1.0 to 2.4 g kg^?1 DM) concentrations were mostly below the required levels for ruminants. The lowest values were detected in February. K levels ranged between 6.6 g kg^?1 DM in February and 23.4 g kg^?1 DM in December; on average, K concentrations decreased about 10 g kg^?1 DM with advancing winter. Ca concentrations (2.9 to 7.4 g kg^?1 DM) hardly changed during winter. Related to higher growth rates of F. arundinacea before December, P and Ca concentrations were diluted, but regarding Mg, more wintergreen F. arundinacea reached higher values than L. perenne especially at the beginning of winter.     

Clonal propagation of rice through proliferation of axillary shoots

Summary Shoot base segments have been explanted from seedlings of rice (Oryza sativa L. subsp. Japonica, cv. Arborio) and grown on agar-solidified MS medium supplemented with different concentrations of four cytokinins: kinetin, BAP, 2iP and zeatin. After one month, segments were explanted from proliferated shoots and subcultured on their respective media. BAP was by far the most effective in inducing shoot proliferation. Highest rates were achieved at the higher concentration used: 5 mg 1^–1. Shoot base segments were subcultured fifteen times consecutively on seven different concentrations of BAP. Shoots grown in the presence of 5 mg 1^–1 of BAP proliferated an average of 12 normal shoots for each base segment throughout the fifteen subcultures. The shoots rooted easily on hormone-free medium. The technique does not require any particular skill, it is very effective and, therefore, can be suggested as suitable for clonal propagation of rice.     

Environmental correlations among grain yield and other important traits of wheat in drylands

Summary Environmental correlation coefficients were computed among all pairs of five traits, namely grain yield, heading date, number of tillers per m², plant height and 1000-grain weight (grain size) using 30 Triticum durum and 30 Triticum aestivum varieties grown in 18 environments. Grain yield was significantly correlated with the other four traits in almost all of the varieties. The mean correlation coefficient over all varieties ranged from 0.58 to –0.83 for durum wheat and 0.66 to 0.88 for aestivum wheat. The correlation coefficients between heading date and the other traits were also significant, ranging from –0.45 to –0.79 in durum wheat and –0.61 to –0.85 in aestivum wheat. The correlation coefficient between number of tillers with plant height and 1000-grain weight were the smallest, 0.19–0.32 in durum wheat and 0.39–0.60 in aestivum wheat. It was concluded that agronomic practices favouring early and good stand establishment in the dry regions will favour the yield components and important adaptive traits, which contribute towards larger yields. Significant differences were found among genotypes in the environmental correlation coefficients and the associated changes in one trait as a result of changes in other traits.     

Identification of rape seed cultivars (Brassica napus) by starch gel electrophoresis of enzymes

Summary Isozyme patterns were used to characterize ten commercial rape seed (Brassica napus) cultivars. Extracts of cotyledons were made 4–7 days after germination and separated by electrophoresis on starch gels. A sample of more than 100 plants of each variety was analysed and stained for 4 polymorphic enzyme loci (Lap, Gpi, Acon, and Sdh). Therewith, it was possible to distinguish all ten rape varieties qualitatively by at least one typical enzyme pattern. Further, it could be demonstrated that all pairs of varieties showed clear qualitative differences in isozyme patterns, when only tow loci were screened (Acon, Sdh). Using ² test of homogeneity all pairs of varieties differ significantly in their frequencies of isozyme patterns for Acon and in all but one for Sdh.     

Studies on sexual variation in mulberry (Morus spp.)

Summary Sex expression in mulberry (Morus spp.) was recorded in 301 varieties, collected from diverse geographical origins, evolved varieties and polyploids maintained at Central Sericultural Research and Training Institute, Berhampore, West Bengal. India (24°6'N and 88°15'E) during 1991–93. Out of total varieties, 49 (16%) male, 161 (53%) female, 52 (17%) monoecious and 39 (13%) were bisexual. Parameters on flowering time, anthesis, floral characters, sex expression and sex reversal were recorded. The indigenous, evolved and polyploids showed early flowering (Jan–Feb) and exotic showed late flowering (Jan–April). The pollen grain viability, seed setting % and other floral behaviour were recorded.     

Strawberry breeding for red core resistance in the Netherlands

Summary The appearance, a few years ago, of red core disease (Phytophthora fragariae Hickman) in strawberry crops in the Netherlands, has made it desirable to grow resistant varieties and to include red core resistance in our breeding programme.An account is given of the results of some field trials in 1968–1970 on a very wet, sandy soil, infected with P. fragariae, involving varieties, selections and seedling progenies.In both years distinct differences in resistance and susceptibility occurred between varieties and selections. The seedling progenies gave significant differences in percentages of surviving, healthy plants.Samenvatting Het optreden van rood wortelrot (Phytophthora fragariae Hickman) enkele jaren geleden in de aardbeiteelt in Nederland, heeft het gewenst gemaakt resistente rassen te telen en resistentie in ons veredelingsprogramma op te nemen.In dit artikel worden de resultaten vermeld van enkele veldproeven met rassen, selecties en zaailingpopulaties in de jaren 1968–69 en 1969–70 op een zeer natte, met P. fragariae besmette zandgrond.In beide jaren traden duidelijke verschillen in vatbaarheid op tussen de rassen en selecties. De zaailingpopulaties vertoonden eveneens duidelijke verschillen in de percentages overlevende, gezonde planten.     

Leaf rust and stripe rust resistance genes transferred to common wheat from Triticum dicoccoides

Linked leaf rust and stripe rust resistance genes introduced from Triticum dicoccoides protected common wheat seedlings against a range of pathotypes of the respective pathogens. The genes were chromosomally mapped using monosomic and telosomic analyses, C-banding and RFLPs. The data indicated that an introgressed region is located on wheat chromosome arm 6BS. The introgressed region did not pair with the ‘Chinese Spring’ 6BS arm during meiosis possibly as a result of reduced homology, but appeared to pair with 6BS of W84-17 (57% of pollen mother cells) and ‘Avocet S’. The introgressed region had a very strong preferential pollen transmission (0.96–0.98) whereas its transmission through egg cells (0.41–0.66) varied with the genetic background of the heterozygote. Homozygous resistant plants had a normal phenotype, were fertile and produced plump seeds. Symbols Lr53 and Yr35 are proposed to designate the respective genes.     

Development of highly sprouting tolerant wheat germplasm with reduced germination at low temperature

The development of sprouting tolerant spring and winter wheat varieties that retain dormancy in cool, wet conditions is a long-term objective in Hokkaido, Japan. A highly tolerant spring dwarf line, “OS21-5”, derived from “Tordo” × “Zenkoji”, was used to develop transgressive spring, “OS38” and “OS74”; and winter, “OW77”, “OW104” and “OW93” wheats. More recently, winter lines with improved agronomic performance, though still deficient in quality and scab resistance, have been identified. In general, germination percentage of mature grain at 10 ^°C was closely related to the mean temperature experienced during the 5 days prior to maturity (dough–yellow ripening stage) and to the capacity to maintain a high amylograph paste viscosity. Dormancy at 10 ^°C appeared to be determined by a combination of genotype and variation in sensitivity to temperature during the later stages of ripening. Genotypes such as “OS38” and ‘OWl04’ were both highly tolerant to germination at 10 ^°C and insensitive to temperature during ripening. By comparison, most of the other cultivars showed a similar, intermediate sensitivity to ripening temperature, and dormancy decreased as ripening temperature increased. Dormancy of‘RL4137’ at maturity, and to a lesser extent ‘Gifukomugi’ and ‘KKI354’, was very sensitive to ripening temperature and useful levels of dormancy only developed under cool ripening temperatures, mean temperature < 18–20 ^°C.