Varietal Combinations Research Articles

Notes on African Euphorbiaceae: XIV

Cephalocroton is reported as new to West Africa. In Croton, a reduction to synonymy is made and new records are reported for Kenya and Somalia. In Cyathogyne, a new record is also reported for Somalia. In Drypetes a new variety is described from Kenya. In Erythrococca, a new record is reported for Mozambique, and a new species is described from Somalia. In Jatropha a new varietal combination is made, a new record is reported for, and a new species described from, Somalia. In Mallotus, a forma is upgraded to the varietal level, and is recorded as new for Mozambique. In Margaritaria a new forma is described. In Neoholstia a new varietal combination is made. In Neopalissya, two new subspecies are described, one for Zimbabwe and one for Tanzania, the latter constituting a new record of the genus for Tanzania. In Phyllanthus, two new records are reported for Mozambique, and one for Kenya. In Ricinus, further information is reported concerning the alleged quellgebiet of this taxonomically rather isolated monotype. In Sapium a new variety is described from Angola and a remarkable brace of colligenda from Tanzania are tentatively attributed to it. In Sibangea, a description is amplified. In Tragia, a lectotype is chosen for a Linnean species. These have all come to light during routine naming of African Euphorbiaceae and the consequent updating of the account of the family for the Flora of Tropical East Africa.

Specific combining ability between six different types of maize (Zea mays L.) obtained from a diallel set of eleven open-pollinated varieties.

In practical hybrid maize breeding, it is necessary to select combinations with a high degree of specific combining ability as well as to improve general combining ability. It is well-known that more genetically distant combinations induce higher specific combining ability and result in more yielding hybrids. Although SUTO et al. (1956) classified the flint types present in Asia into five types, namely, North American, Caribbean, European, Aegean, and Persian, there have been no reports on the specific combining ability between the six types which are composed of the above five flint types in addition to a dent type, American dent. The purpose of this study was to investigate the relationship between the modes of varietal combinations and specific combining ability effects estimated from the analysis of a diallel set of eleven open-pollinated varieties belonging to the six types, and to identify a general trend of specific combining ability between the six types. The results obtained here were as follows: l) Combinations between different types, especially between flint and dent types, were superior to those within same types in specific combining ability effect and F1 yield. 2) High specific combining ability was observed in crosses between Caribbean and American dent, and between Persian and other types except for European and Aegean. 3) Specific combining ability effects were closely related to genetic divergence estimated from the previous classification results, in which the values of specific combining ability effects increased with increasing genetic divergence.

Intraspecific chromosome manipulation

Whole chromosome manipulation within a crop species is restricted in the main to the hexaploid bread wheat, Triticum aestivum (2 n = 6 x = 42). Directed manipulation within this group is possible because aneuploidy is tolerated, and at least 60 monosomic sets, representative of many of the successful wheats of the world, are available. These permit, after recurrent backcrossing and cytological selection, the substitution of whole chromosomes from one variety into another. Substitution lines have been used to identify chromosomes and genes responsible for varietal differences affecting a range of important agronomic characters, and provide the most efficient method of genetical analysis available in wheat or indeed in any crop species. The length of time taken to develop substitution lines is, however, a weakness of the approach. A method in which monosomic sets are crossed reciprocally overcomes this weakness and permits the identification of significant chromosomal effects in one to two generations. Modifications to the method enable chromosomal effects to be studied in any varietal combination even though monosomic sets are not available in all the varieties being studied. The results obtained by intraspecific chromosome manipulation have been exploited in the development of a high-yielding spring wheat after recombination of a single chromosome substituted into a winter wheat. This example suggests that the methods may have direct applications to plant breeding where large chromosomal effects have been identified. This is particularly relevant where the variation concerned is difficult to assess. These methods also have a major part to play in increasing the understanding of the genetic architecture of wheat. It is also likely that they will have value in transferring useful genes from distantly related varieties.

A general approach to the concept of varietal ability for synthetic varieties

Genetic effects for varietal value are defined at the level of the population of k-parent synthetic varieties. A simple expression for the total variance among synthetics arises directly from these definitions. A general expression for the covariance among related synthetics is given. Genetic effects are also defined in a completely general way so as to allow for any system of testing and used to derive an expression for the genetic advance in recurrent selection for varietal value. Covariances between relatives evaluated in the system of testing and in varietal combination are introduced, allowing a direct expression of the genetic advance in varietal development when parents are selected either individually or in groups. Some general implications for plant breeding are outlined.

New Combinations and One New Variety in Trifolium (Leguminosae)

This report includes fifteen varietal combinations and a description of a new variety,T. haydenii var.barnebyi.

The concept of varietal ability in plant breeding

At the population level, the general varietal ability of a genotype is defined as the expectation of all possible varieties of a given type with this genotype. Specific varietal abilities of order 1, 2, 3..., are defined as interactions from the combined effect of 2, 3, 4... parents in varietal combinations. Genetic effects for varietal value and for the criterion of test are introduced. They allow an expression of the covariance between the value of a genotype according to the testing system and the value of its progeny from random mating in varietal combination. So a general expression of the genetic advance in the varietal value of a population improved by recurrent selection can be given whatever the type of variety and the testing system. The genetic advance is also considered at the level of the varieties. Some examples of prediction formulae for varietal abilities are given for hybrids, synthetics and lines. The problem of prediction of the ability of a genotype to give lines with the best general varietal abilities is also considered.

Methods of analysis of a competition diallel in Italian ryegrass with varying mixture proportions

SUMMARYTwo methods of analysis of variance of experiments involving diallel arrangements of binary mixtures and monocultures where the former are each represented by a linear replacement series (de Wit, 1960) to detect mean quadratic and quartic patterns among the monocultures and different mixture types, and array differences with respect to linear, quadratic, cubic and quartic effects are given. These are applied to data from an experiment on Italian ryegrass where the four varieties 1145 and S. 22 (diploid), IG2 and Tetila (tetraploid) are mixed in the proportions 75:25, 50:50 and 25:75.Significant mean quadratic effects for D.M. yield at certain harvests are due to higher yields from monocultures than mixtures, and a mean quartic effect at one harvest reflects a lower yield from 75:25 mixtures than 50:50 mixtures or monocultures. Array differences for linear and quadratic effects are largely a property of the ploidy contrast. Specific mixture effects were recognized for two varietal combinations, mixtures between the two tetraploid varieties showing some yield depression, and those between the two commercial varieties (RvP and Tetila) a considerable increase. No meaningful significant effects were detected for in vitro digestibility.Further analysis of total D.M. yield by means of the regression of array covariance (Wr) on to array variance (Vr) show, as expected, a closer relationship of Wr and Vr with the non-recurrent component at a frequency of 75% than at 50% or 25%, but the significant departure of the slope from unity is interpreted as evidence that no reliable information as to the relative competitive abilities of the varieties can be obtained from these statistics. Examination of the de Wit replacement graphs strongly suggests a ranking of competitive ability which accords with the known morphology of the varieties.

Notes on Amaranthaceae: 2

Summary. Within the genus Aerva, the sexual and other diversity of A. lanata (L.) Juss. ex Schultes and A. leucura Moq. is discussed, A. sansibarica Suesseng. and A. incana Suesseng. being reduced to the synonym of A. lanata; variation in A. javanica (Burm. f.) Juss. ex Schultes var. bovei Webb is also discussed. Aerva curtisii Oliv. and A. cochinchinensis Gagnep. are transferred to a new genus Psilotrichopsis, and A. monsoniae Linn. f. to a new genus Trichurus. Psilotrichum is revised in SE. Asia. Pupalia orbiculata Heyne ex Wall. becomes a variety of P. lappacea (L.) Juss. The relationships of Digera Forssk.. Neocentema Schinz and Pleuropteranthera Franchet are dealt with; finally, Amaranthus dubius Mart. ex Thell., A. lividus L. and Centrostachys aquatica (R.Br.) Wall. ex Moq. are typified. A new varietal combination is made for what has previously been thought to be the 'typical' variety of Achyranthes aspera L., and for two other varieties of this species. Aerva lanata (L.) Juss. ex Schultes and A. leucura Moq. A. leucura Moq. has been maintained as a species distinct from A. lanata for the 'Flora of Tropical East Africa' account as it stands at the moment. This reflects no great conviction that such is the true state of affairs, but rather that even after protracted study I find that I have nothing of significance to add to our knowledge of the taxonomy of these two plants. As Hauman (1951: 59) remarks, A. leucura is an ill-defined and unconvincing species, comprising as it does plants which resemble a paniculate variety of A. lanata, and identical with the latter in flowers, fruit and seed. Were the two wholly sympatric with numerous intermediates, one would unhesitatingly subordinate A. leucura as a variety of A. lanata. However, while A. lanata ranges through most of tropical Africa to South Africa (where, however, it appears to be rare) and thence from Arabia eastwards through tropical Asia to the Philippines and New Guinea, A. leucura is confined to Africa southwards from Uganda and Kenya (one rather atypical specimen only seen from the latter country) to South Africa, where it is common. Similarly, even within the F.T.E.A. range A. leucura is, if one may judge from herbarium material, much more restricted in altitude range than A. lanata, scarcely descending below 6o00 m, while A. lanata occurs commonly at sea level. It would perhaps be fashionable to make a subspecies of A. leucura-a course of action which would merely create a new binomial to no profit; for the moment, it seems best to continue to regard these two as vicarious species. Such intermediates as occur are chiefly found in the area where the two plants overlap in abundance (e.g. in Tanzania), and may as well be due to hybridization as to any other course. Genetical investigation is much needed here. As well as being a troublesome genus taxonomically the sexuality of Aerva appears complex. The widespread A. javanica (Burm. f.) Juss. ex Schult. seems to be constantly dioecious; conversely, all the material which I have examined of the Indian A. sanguinolenta (L.) Bl. (A. scandens Roxb.) has had well-developed anthers and stigmas, though Backer (1949: 85) describes it as having flowers hermaphrodite or female. But in A. lanata there is a more involved situation. In the Flora Malesiana region it is, according to Backer,

Notes on Asiatic Bignoniaceae

The taxonomy, nomenclature and distribution of a number of Asiatic Bignoniaceae are considered, especially from Thailand. Two species of Radermachera are transferred to a new genus Barnettia; Spathodeopsis collignonii is recorded for the first time from Thailand; the names Stereospermum grandiflorum and S. wallichii are sunk under S. neuranthum; the confused nomenclature of S. chelonoides and S. personatum is elucidated, with a new varietal combination; new records of Nyctocalos shanica are established from Thailand and collections of the other species reviewed; and, finally, the status of the genus Saritaea, naturalized in Thailand, is maintained after review.

A Biosystematic Study of the Phlox Cuspidata-Phlox Drummondii Complex

The emphasis in this investigation of the P. cuspi- data-P. drummondii complex was placed on field studies and experi- mental breeding. Chromosome counts were made from bud material collected from 50 populations representing all the taxa. All meiotic counts were n 7. Ecological information was gathered and generalized maps showing the distribution of each taxon considered were made. Populations of a hybrid and/or introgressed nature were noted. Three populations were analyzed using the scatter diagram technique of Anderson. One of these, a hybrid population, showed a recoin- bination spindle and supported the belief that the population was of hybrid derivation. Pure populations of the putative parental types were analyzed by the same technique. A total of 464 flowers were emasculated and pollinated; 21 of these crosses involved P. roemeriana as the pollen parent. Breeding cages were utilized in the study. P. drummondii var. littoralis showed a low degree of autogamy. P. cuspidata var. humilis was highly auto- gamous. The other taxa did not set any seeds by autogamy within the cages. The over-all average of normal-appearing seeds produced, as compared to the number theoretically possible, was 58 per cent. Although 771 seeds of normal appearance were obtained from the crosses within the P. cuspidata-P. drummondii complex, efforts to germinate these seeds proved fruitless. A brief systematic review is presented and a key to the annual taxa of Phlox is included. The authors recognize two species within the P. cuspidata-P. drummondii complex. Two varieties are recognized within the species P. cuspidata. Two subspecies are recognized in the species P. drummondii: Subspecies GLABRIFLORA which includes two varieties and subspecies DRUMMONDII with four varieties. Three new varietal combinations were made in this disposition: P. drummondii var. glabriflora (Brand) Erbe; P.d. var. goldsmithii (Whitehouse) Erbe; and P.d. var. tharpii (Whitehouse) Erbe.

Studies in Penstemon-IX.: Notes on Northwestern American Species

The preparation by the junior author of a treatment of Penstemon for a flora of the Pacific Northwest, in consultation with the senior author, has necessitated the validation of some herbarium names, and suggested the desirability of a few other taxonomic and nomenclatural changes. The authors are in agreement about all matters discussed in this paper, except that here as elsewhere the subspecies of the senior author are the varieties of the junior author. All subspecific combinations are therefore attributed to the senior author alone; some of the comparable varietal combinations will be made by the junior author in the text of the flora. Except as otherwise indicated, all specimens cited are deposited in the herbarium of the New York Botanical Garden. The name Gerardia fruticosa Pursh was cited as a synonym by Hooker in the original publication of Penstemon menziesii Hook. Fl. Bor.-Am. 2: 98. 1838. Hooker's name is illegitimate under Article 73 of the International Code of Botanical Nomenclature (1952), because, as circumscribed by him, it included the type of an epithet (fruticosus) which ought to have been adopted under the rules. Penstemon menziesii Hook. is now generally regarded as specifically distinct from P. fruticosus (Pursh) Greene, but Hooker's name, being illegitimate, cannot be retained. The oldest available name for the species which has customarily been known as P. menziesii is P. davidsonii Greene, but the types of these two names belong to different subspecies. As noted in Article 81 of the rules, the illegitihinacy of the name P. menziesii is no barrier to the use of the epithet in a different category, and the following name is therefore proposed.

Studies on the transplantation of the immature embryos in cereals. III. On the earing behaviour of the immature wheat embryos transplanted into the endosperms of the other varieties having different earing characters.

1. Using eight varieties of wheat, which are classified into three major groups of different earing habit (See Tabe 1), a number of transplantings of immature embryos into deyeloping seeds was carried out. An excised immature embryo of a foreign or its owh variety was inserted into the endosperm of a developing seed as depicted in Fig. 1., thus obtaining the matured viable seeds, each with two embryos, one of which is the proper and the other the transplanted. The author succeeded in raising a large number of such artificial twin seeds, eacb of which consists of two embryos of different varieta.1 nature or of the same. The pairs of plants were grown up from a number of such twin seeds, and their flowering responses were examirLed, making comparisons within each pair of sister plants as well as among the dlfferent pairs derived from various varietal combinations (See Table 3). 2. There can not be noticed any differences among the earing responses of the plants grown up from the transplanted embryos which, have the same genetic constitution but matured under different endospermous condition of the foreign varieties. In other words, those plants develop a quite similar number of leaves on their main stem before the ear-emergence, resuiting in neither promoting nor delaying the anthesis. The plants grown up from proper intact embryos of those twins show also quite similar situation in their earing behaviour, i. e., an additional transplanting of a foreign embryo having different earing habit into the developing seed does not exert any discernible influence on the earing character of the proper intact ernbryo.

A REVISION OF MALAYSIAN BAUHINIEAE

This revision deals with the tribus Bauhinieae(Caesalpiniaceae)as occurring in Malaysia.The tribe includes the genera Bauhinia L. s.str., Bracteolanthus de Wit gen. nov., Gigasiphon Drake del Cast.,Lasiobema (Korth.) Miq., Lysiphyllum (Benth.)de Wit gen. & stat. nov., Phanera Lour.,and Piliostigma Hochst. Bauhinia is reduced to the original Lin-nean delimitation; 9 species are treated (inclusive of a number of varieties) ; 2 species are reduced to the rank of varieties and 3 new varieties are described, accounting for 3 new varietal combinations and 3 new varietal names.Bracteolanthus contains a single species for which a new combination is proposed. Gigasiphon is represented by 3 species; 3 new specific combinations are made.Lasiobema is represented by 5 species; in this ge- nus 1 new species is described, 4 new combinations and 1 new varietal combination are proposed,and a new but insufficiently represented species is recorded.Some new combinations for extra-Malaysian species are also proposed.Of Lysiphyllum 2 species are treated; 2 new combinations and some new combinations for extra-Malaysian species were necessary.Pha-nera is by far the largest genus:44 species,many of which are divided into subspecies and/or varieties.The genus is subdivided into three sub-genera, Phanera,Biporina de Wit, and Austrocercis de Wit.Of these,subgenus Phanera, in its turn, contains 3 sections, all new, viz Pha.nero-siphon, Meganthera, and Micranthera.Subgenus Biporina comprises the 3 new sections Bifoliola, Palmatifolia,and Cinnamomifolia. Subgenus Austrocercis consists of a single species.The recognition of Phanera as a genus, as well as the description of new taxa and the revaluation of some previously described ones made necessary a large number of new names and new combinations.

Nomenclatural and Distributional Notes on Botrychium lanceolatum

Most modern writers accredit Angstroem with the original transference of Gmelin's Osmunda lanceolata to the genus Botrychium. Among botanists who have so given credit to Angstroem may be mentioned Fernald (Rhodora 17: 87-88. 1915),-Maxon (Rhodora 20: 19. 1918), Broun (Index North American Ferns, p. 35. 1938) and myself (Mem. Torr. Club 19(2): 90. 1938). Subsequent to my publication, S. J. Smith mentioned to me that Ruprecht had listed the binomial Botrychium lanceolatum nine years before the date when it was published by Angstroem. Ruprecht's ideas with respect to Gmelin's Osmunda lanceolata evidently underwent change in 1845. On page 33 of part 3 of Beitrage zur Pflanzenkunde des Russichen Reiches, he listed this as 488. Botrychium (Lunaria) lanceolatum* with the synonym Osmunda lanceolata Gmel. jun., 1768. This is the basis for the varietal combination under B. Lunaria cited by me on p. 90 of my Monograph. On p. 92 of part four of the Beitrage, Ruprecht listed Botrychium lanceolatum.* The 1. and * indicated that he regarded B. lanceolatum to be a species new to the flora of St. Petersburg. Ruprecht did not directly cite the basinym, but he cited his 48f/ mentioned above. Here Gmelin's binomial and the date of its publication were indicated, but no bibliographical citation. Ruprecht's intention appears clear. Since he did cite the date of Gmelin's publication, I am now inclined to accredit him with first valid publication of Botrychium lanceolatum. His binomial is neither a nomen nudum nor a nomemn dubium. Its application seems reasonably definite. The citation thus should be: Botrychium lan45

CROSSING RELATIONSHIPS AMONG HYBRID AND SPECIFIC PLUM VARIETIES, AND AMONG THE SEVERAL PRUNUS SPECIES WHICH ARE INVOLVED

THE DATA presented here were accumulated during the course of a breeding project with plums, carried on over a period of 8 years while the writer was on the staff of the Texas Agricultural Experiment Station. A brief preliminary abstract has summarized some of the material in this report (Flory, 1944). No attempt is made here to present detailed data concerning attempted varietal combinations. Effort is directed, rather, toward determining and summarizing the crossing behavior, and the effective pollenizing values, of variety groups when considered collectively from the standpoint of similar botanical origin. MATERIAL.-Thirty-seven different varieties were used in the selfs and in the attempted cross combinations on which this report is based. These varieties, together with the species of Prunus from which they originated, follow: