A note on the origin of Kalanchoë x vadensis Boom & Zeilinga (Crassulaceae)

Summary K x vadensis is a hybrid of K. blossfeldiana and K. marmorata obtained after doubling the number of chromosomes.     

Avoidance of leaf rust fungi in wild relatives of cultivated cereals

Summary Avoidance of rust fungi that was based on poor appressorium induction was previously found in Hordeum chilense. In the present study 95 accessions of Triticeae were screened for avoidance of Puccinia hordei. The percentage of appressorium formation per germinated spore ranged from 6 to 90%. On none of the 41 accessions of Aegilops, Agropyron, Elymus, Secale, Thinopyrum or Triticum studied was the rate of appressorium formation lower than 25%. Lower rates of appressorium formation were, however, found on accessions of wild barley species Hordeum brachyantherum, H. marinum, H. parodii and H. secalinum. Its implications in cereal breeding are discussed.     

Relation between wheat-rye crossability and seed set of common wheat after pollination with other species in the Hordeae

Summary Cultivars of common wheat (Triticum aestivum L. em. Thell.) of high wheat-rye (Secale cereale L.) crossability set more seed with pollen of other related species than did wheats of low wheat-rye crossability. This was found to be true for pollen parents from the genera Triticum, Aegilops, Secale, Agropyron and Elymus.     

Mechanisms and diversity of resistance to sorghum shoot fly,Atherigona soccata

Sorghum shoot fly, Atherigona soccata, is one of the important pests of postrainy season sorghums. Of the 90 sorghum genotypes evaluated for resistance to this pest, RHRB 12, ICSV 713, 25026, 93046 and 25027, IS 33844‐5, Giddi Maldandi and RVRT 3 exhibited resistance in postrainy season, while ICSB 463, Phule Anuradha, RHRB 19, Parbhani Moti, ICSV 705, PS 35805, IS 5480, 5622, 17726, 18368 and 34722, RVRT 1, ICSR 93031 and Dagidi Solapur showed resistance in rainy season, suggesting season‐specific expression of resistance to A. soccata. ICSB 461, ICSB 463, Phule Yasodha, M 35‐1, ICSV 700, 711, 25010, 25019 and 93089, IS 18662, Phule Vasudha, IS 18551 and 33844‐5 and Barsizoot had fewer deadhearts than plants with eggs across seasons, suggesting antibiosis as one of the resistance mechanism. Five genotypes exhibited resistance with high grain yield across seasons. Correlation, path and stepwise regression analyses indicated that leaf glossiness, seedling vigour, trichome density, oviposition and leaf sheath pigmentation were associated with the expression of resistance/susceptibility to shoot fly, and these can be used as marker traits to select and develop shoot fly‐resistant sorghums.     

Reaction of tritordeum to Fusarium culmorum and Septoria nodorum

Summary Hordeum chilense is a wild barley extensively used in wide crosses in the Triticeae. It could be a valuable source of resistance to Fusarium culmorum and Septoria nodorum. Some H. chilense x Triticum spp. amphiploids, named tritordeums, were more resistant than the parental wheat line to these diseases, others were not. Average contents of ergosterol and deoxynivalenol (DON) suggested that resistance to colonization by Fusarium was the highest for Hordeum chilense, followed by tritordeum and wheat in decreasing order. In particular, the H. chilense genotypes H7 and H17 enhanced the wheat resistance to F. culmorum in its tritordeum offsprings. Resistance to S. nodorum in tritordeum was not associated with tall plant height. There is sufficient genetic variation for resistance to F. culmorum and S. nodorum among tritordeum to allow the breeding of lines combining short straw and resistance to both diseases.     

Breeding apomictic bahiagrass (Paspalum notatum Flügge) with improved turf traits

The development of a turf‐type bahiagrass could have a remarkable impact on the billion‐dollar turf industry in the south‐eastern United States. The goals of this study were to (i) select bahiagrass genotypes with improved turf attributes and (ii) determine the reproductive mode and seed fertility of selected genotypes. The population included mutants, wild types, hybrids and standard cultivars evaluated at two locations for two years. Morphological variation was observed and clonal repeatability (H²) ranged from 0.27 to 0.90. Flowering was extremely reduced in some mutants, which also exhibited dark green colour, finer texture and reduced canopy height. Cytoembryological observations revealed that diploids reproduced sexually and tetraploids by obligate or facultative apomixis. Genotypes with superior seed fertility were identified, while others were comparable to the standard cultivars. While mutant plants exhibited great morphological variation, the random mutations did not affect their reproductive mode, validating the use of mutagenesis in apomictic species. The high H² indicated that selection for improved turf attributes could be successfully performed with the advantage of clonal seed propagation.     

Disease resistance in protected crops and mushrooms

Summary Cultivars of tomatoes, cucumbers, lettuce and peppers have been bred for resistance to one or more pathogens. Some tomato and cucumber cultivars have resistance to a wide range of diseases. Resistance has been transient in many cases and a succession of cultivars with new genes or new combinations of resistance genes has been necessary to maintain control. There has been a number of notable exceptions and these have included durable resistance to such pathogens asFulvia fulva and tomato mosaic virus. With lettuce the resistance situation is complicated by the occurrence of fungicide resistant pathotypes. There are no strains ofAgaricus bisporus purposely bred for disease resistance.In protected flower crops only resistance to Fusarium wilt in carnations has been purposely bred but differences in disease resistance are apparent in cultivars of many ornamental crops. This is particularly so in chrysanthemums where there are cultivars with resistance to many of the major pathogens. Similar situations occur with other flower crops and pot plants. Cultivars of some species have not been systematically investigated for resistance.The need for genetic resistance will increase with the further reduction, in the limits on pesticide use and an increasing public awareness and importance of pesticide pollution.ADAS is an executive agency of the Ministry of Agiculture, Fisheries and Food and the Welsh Office.     

Genetic constitution and diversity in four narrow endemic redwoods from the family Cupressaceae

The genetic constitution and diversity of four relictual redwoods are discussed in this review. These include monotypic genera of the family Cupressaceae: coast redwood (Sequoia sempervirens), giant sequoia (Sequoiadendron giganteum), dawn redwood (Metasequoia glyptostroboides), and alerce (Fitzroya cupressoides). All four species are narrow endemics, share a number of common phenotypic traits, including red wood, and are threatened species. Fossil history suggests that the ancestors of redwoods probably originated during the Cretaceous and Tertiary periods and flourished thereafter for millions of years. Towards the end of the Tertiary period began their decline and struggle for existence that continued during the subsequent geologic upheavals and climate changes, until the survival of the present-day redwoods in the current restricted locations in the world (USA, China, and South America). Although two species, Sequoiadendron and Metasequoia, are diploids (2n = 22), and the other two are polyploids: Fitzroya a tetraploid (2n = 4x = 44), and Sequoia a hexaploid (2n = 6x = 66); they all share the same basic chromosome number x = 11. The genome size in the hexaploid Sequoia is one of the largest (31,500 MB) in the conifers, while the genome sizes of diploid Metasequoia and Sequoiadendron are about one-third (~10,000 MB) of Sequoia. Genetic diversity in the redwoods is lower than most other gymnosperms, except in Sequoia, which seems to rank near the upper quarter of the coniferous forest trees. Genomic research is sparse in the redwoods, and should be pursued for a better understanding of their genome structure, function, and adaptive genetic diversity.     

Inheritance of fruit colour in a wild Russian red raspberry seedling

Summary A new gene, i, from a self-incompatible wild Russian Rubus idaeus seedling is described. The gene i interacts with the fruit colour gene T, Tii plants having apricot instead of red fruits, and spines, leaves and stems pigmented to varying degrees. A deficit of apricot-fruited seedlings in progenies segregating for i could be explained by linkage between i and the self-incompatibility S locus with a crossover value of approximately 26.7%.Segregations for spine colour in crosses and backcrosses of the Russian seedling with two green-spined (ttII) raspberries selected for their yellow fruit colour, showed that both the latter carried the spine colour intensifier gene P. This suggests that earlier authors were incorrect in attributing the apricot fruit colour developed by some tt plants to a pleiotropic effect of P.     

The induction in vitro of adventitious shoots in Rosa

Summary Adventitious shoots were formed on excised leaves, roots and callus of Rosa persica x xanthina and on excised leaves of R. laevigata and R. wichuraiana on culture media that included BAP and NAA as growth regulators. Shoots formed freely on freshly cultured callus of R. persica x xanthina but their production declined in successive cultures and ceased after twelve weeks. Transplantation to soil was improved by rooting plantlets in cellulose plugs in vitro and transferring plantlets to soil while still in the plugs.     

Distribution,ecology and reproductive biology of wild tomatoes and related nightshades from the Atacama Desert region of northern Chile

Over the past 20 years, several expeditions were made to northern Chile to collect populations of wild tomatoes (Solanum chilense, S. peruvianum) and allied nightshades (S. lycopersicoides, S. sitiens), and obtain information about their geographic distribution, ecology and reproductive biology. Restricted mainly to drainages of the Andean and the coastal cordillera, populations are geographically fragmented. The two nightshade species are rare and threatened by human activities. Adaptation to extreme aridity and soil salinity are evident in S. chilense and S. sitiens (the latter exhibits several xerophytic traits not seen in the tomatoes) and to low temperatures in S. lycopersicoides and S. chilense. All tested accessions are self-incompatible, with the exception of one S. peruvianum population collected at the southern limit of its distribution. Several distinguishing reproductive traits—anther color, attachment, and dehiscence, pollen size, and flower scent—suggest S. sitiens and S. lycopersicoides attract different pollinators than S. chilense and S. peruvianum. The four Solanum spp. native or endemic to Chile provide a variety of novel traits which, through hybridization and introgression with cultivated tomato, could facilitate development of improved varieties, as well as research on a variety of basic topics, including plant-pollinator interactions, abiotic stress responses, and evolution of reproductive barriers.     

The exploration of genetic resources of Portuguese cabbage and kale for resistance to several Brassica diseases

Summary Twenty three accessions of nine Portuguese cabbage and kale land races from different geographic origins were tested at the seedling stage for resistance to several important brassica diseases. Resistance to downy mildew (Peronospora parasitica), expressed as necrosis of the cotyledon mesophyll, was found in all the accessions. Type A resistance to cabbage yellows (Fusarium oxysporum f. sp. conglutinans race 1) was present in most of the landraces. Resistance to clubroot (Plasmodiophora brassicae race 6) was found in one accession of the Portuguese tree kale. High resistance to blackleg (Leptosphaeria maculans) and white rust (Albuco candida) was not detected, although several accessions showed 20 to 30% of plants with intermediate expression of resistance. All Portuguese cole accessions were susceptible to blackrot (Xanthomonas campestris pv. campestris).     

Production and characterization of intergeneric diploid cybrids derived from symmetric fusion between Microcitrus papuana Swingle and sour orange (Citrus aurantium)

Plants were regenerated from intergeneric somatic hybridization between embryogenic protoplasts of Microcitrus papuana Swingle and leaf-derived protoplasts of sour orange (Citrus aurantium L.) via electrofusion. The regenerated plants were morphologically similar to the leaf parent in growth vigor, leaf and branch structure. FCM analysis showed that they were diploids. Simple-sequence-repeat (SSR) and cleaved-amplified-polymorphic-sequence(CAPS) were employed for hybridity characterization. SSR banding patterns of the regenerated plants were identical to the leaf parent, sour orange, indicating that they possessed nuclear component derived from sour orange. DNA amplification with chloroplast and mitochondrial universal primers, followed by restriction endonuclease digestion, revealed polymorphism between the fusion parents. Therefore, this method was used to determine the cytoplasmic compositions of the regenerated plants. Banding patterns for all the polymorphic primer/enzyme combinations of the regenerated plants were similar to those of the embryogenic parent, M. papuana, suggesting that only the cytoplasmic components derived from the embryogenic parent were present in the regenerated plants. FCM, SSR and CAPS demonstrated that intergeneric diploid cybrids have been successfully obtained by symmetric fusion. Related results concerning nuclear and cytoplasmic composition of previous diploid somatic hybrids and potential mechanism for regeneration of such kind of plants are discussed herein. This revised version was published online in July 2006 with corrections to the Cover Date.     

Flag Leaf Senescence, as Evaluated by Numerical Image Analysis, and its Relationship with Yield under Drought in Durum Wheat

Senescence was evaluated at different stages of the grain‐filling period in eight durum wheat varieties using numerical image analysis (NIA). The varieties were grown under early, severe drought conditions on the high plains of Sétif in Algeria. After flowering, three different irrigation treatments were applied. Treatment effect was small, while a genotypic effect was noted for most of the senescence parameters. Senescence correlated to biomass, while the maximal rate of senescence, V_smax, correlated to thousand‐kernel weight. The potential of the method of numerical image analysis for monitoring flag leaf senescence, detecting genotypic variability and selecting genotypes with delayed senescence is discussed.     

Breeding barriers between the cultivated strawberry, Fragaria × ananassa, and related wild germplasm

Five-hundred interspecific and intergeneric crosses were performed among accessions of the wild strawberries Fragaria vesca(2x), Duchesnea indica (8x), Potentilla tucumanensis (2x) and 9 genotypes of the cultivated strawberry, Fragaria×ananassa (8x), following an incomplete diallele mating design. Crosses between D. indica and F.×ananassa produced many putative hybrids when D. indica was used as female but a few achenes and plants when used as male; therefore, pollen-pistil compatibility relations were analyzed by fluorescence microscopy in this direction of the cross. Of the genotypic combinations, 78.6% were incompatible at the stigma level and 17.2% at the first third of the style. Only 3.6% were pollen-pistil compatible and produced fruits with achenes (seven did not germinate or originated short-lived plants and nine produced normal plants). F.vesca×F.×ananassa crosses produced 35 hybrid achenes but only 14% germinated, yielding short-lived plants; histological analyses revealed that inviable seeds had less developed (or collapsed) endosperms and smaller embryos than control plump F. vesca seeds. P.tucumanensis was only used as male, with negative results. These species and genera are partially isolated by a complex system of pre- and post-zygotic barriers. Knowledge of their nature would allow the breeder to devise strategies to put the genetic variability available in the group into a useful form. This revised version was published online in July 2006 with corrections to the Cover Date.     

A Novel Breeding Approach in Quest of Temperature Sensitive Genic Male Sterile Lines Among Rice Intersubspecies Derivatives

Summary An investigation was made to exploit an innovative tool viz., thermosensitive genic male sterile (TGMS) system in twoline inter-subspecies rice hybrids using 132 hybrids involving four TGMS lines viz., TS15, TS16, TS18 and TS29 and thirty three testers viz., 17 indicas, 7 japonicas and 9 javanicas by line × tester method at Paddy Breeding Station, Tamil Nadu Agricultural University, India. Pre-ponderence of non-additive gene action for yield and yield attributing traits was observed by analysing combining ability. TGMS lines TS18, TS29 and the testers CB96073, CB96026, CB94247, TNAU 94241 (indicas), Gohykumangoku (japonica), Dular, PRR16 (javanicas) were good general combiners. The hybrids TS29 × TNAU 94241 (indica/indica), TS 18 × Yamadanishiki (indica/japonica) and TS29 × Dular, TS29 × PRR16 (indica/javanica) were promising for heterosis breeding programme. The japonica tester Gohykumangoku and javanica testers Dular and CPSL0-17 exhibited strong heterosis for spikelet fertility when crossed with TGMS lines TS 16, TS 18, TS 29 indicated that these lines may possess wide compatible gene (WCG) for spikelet fertility. Based on mean performance, standard heterosis and sca for yield and yield traits, the inter – subspecies hybrids viz., TS29 × TNAU 94241, TS18 × TNAU 94241, TS29 × CB96073, TS29 × CB94247, TS29 × CB96026 (indica/indica) TS18 × Yamadanishiki, TS29 × Gohykumangoku (indica/japonica), TS29 × Dular, TS29 × PRR16 (indica/javanica) exhibited high heterosis over check hybrid CORH2 and the above hybrids can be exploited commercially. The present investigation revealed that the TGMS system may utilized as an innovative tool for developing inter subspecies two line hybrids with strong heterosis in rice.     

The inheritance of fruit yield and stolon production in everbearing strawberries

Summary The everbearing progeny from crosses between three short-day and four everbearing genotypes were assessed for early fruit yield and stolon production. General combining ability (GCA) was found to be important for fruit yield but specific combining ability (SCA) was more important for stolon production. The results suggested that it should be possible to combine early fruiting and adequate stolon production in an everbearing genotype. The breeding strategy necessary to achieve this aim is discussed.     

Einfluß des Stickstoffangebotes auf Substanzbildung, Erntegewicht und Qualität der Zuckerrübe unter besonderer Berücksichtigung von Temperatur und Globalstrahlung in Gefäßversuchen

Influence of nitrogen supply on dry matter production, yield and quality of sugar beet with special reference to temperature and irradiance in pot experiments
The influence of nitrogen on yield and quality of sugar beet has been studied in many experiments. In comparison, little is known about the changes in sugar beet metabolism caused by increasing the nitrogen supply. The experiments described in this series of papers deal with the influence of nitrogen supply on mineral metabolism. This first paper describes the influence of nitrogen on dry matter production, yield and quality of beet with special reference to temperature and irradiance. The experiments, conducted in 1988 and 1989 using sand culture in pots, included five nitrogen levels. These treatments were sampled five times during the season and at harvest time. Overall, in 1989 sugar yield (g/pot) was 30 to 50 % greater than in 1988. In 1989 there was only a little more irradiance and duration of sunshine (7 and 11 % respectively) than in 1988, and the larger yield in 1989 was probably caused by a bright period of four weeks in May/June. Where least nitrogen was supplied, deficiency symptoms appeared in early June. When this happened an ammonium-urea solution was added to the leaves: it increased growth, but not enough to equal the white sugar yield of the treatment where the sand was given the same amount of N at the beginning of the season.     

氮磷配施对西藏河谷农区燕麦与箭筈豌豆混播产量及品质的影响

在海拔4 300m的西藏河谷农区,进行了N、P配合施肥对混播燕麦与箭筈豌豆产量及品质影响的研究。结果表明：刈割期为燕麦乳熟期/箭筈豌豆结荚期,混合饲草产量最高,饲草粗蛋白、粗脂肪含量较高,而酸性洗涤纤维（ADF）与中性洗涤纤维（NDF）较低。N、P及其互作对混播燕麦与箭筈豌豆株高、产量、养分含量的影响显著;在相同施P水平下,随着N的增加,干草产量、株高和粗蛋白呈现先增后减的变化趋势;粗脂肪、ADF和NDF含量随氮肥施用量的增加有不同程度的降低;在相同施N水平下,随磷肥施用量的增加,粗蛋白、粗脂肪、ADF呈增加的趋势,而NDF逐渐降低。施用氮（纯N）140kg/hm ²、磷（P₂O₅）60kg/hm ²处理组合干草产量最高为16 636kg/hm ²,比不施肥对照组增产60.47%;蛋白质含量最高达18.42%。说明N、P施用量分别为140kg/hm ²、60kg/hm ²可作为该地区燕麦与箭筈豌豆混播种植的推荐施肥量。     

Time course of cannabinoid accumulation and chemotype development during the growth of <Emphasis Type="Italic">Cannabis sativa</Emphasis> L

The time course of cannabinoid accumulation in the leaves of individual plants of three Cannabis accessions was determined by gas-chromatographic analysis in greenhouse-grown plants. The total amounts and the concentration ratios of CBD, THC and CBG were determined; two accessions (an experimental hybrid, (21R × 15R) × NL, and plants from a seized seed lot) were found chemotypically uniform, with all plants belonging to chemotpe II (mixed) and I (high THC) respectively. The Carmagnola accession showed chemotypic heterogeneity, with a majority of plants belonging to chemotype III. The CBD/THC and CBG/CBD ratios were shown to be largely constant in the leaves, since 28 and until 103 days after sowing, and consistent with the ratios determined on mature inflorescences. CBD and THC maximum amounts in the leaves showed a peak in the leaves around 80 days from sowing, and were shown to be simultaneous during the growth period, irrespective of the chemotypes. Callus cultures were obtained from all the five different chemotypes (I, II, III, IV, V), and GC analyses were performed. Independently of the type and amount of cannabinoids in the mother plants, it was confirmed that callus cultures of Cannabis were not able to produce detectable amounts of any cannabinoids.