Weather damage reduces the value of commercial mungbean. but hard‐seededness can reduce the level of damage. However. attempts lo breed large‐ and hard‐seeded mungbean varieties have been unsuccessful. To understand the relationship between seed weight and hard‐seededness. these trails were investigated using a quantitative trail loci (QTL) mapping approach with a recombinant inbred population derived from a cross between a completely soft‐seeded variety and a completely hard‐seeded genotype. The two parental genotypes also had a sixfold difference in seed weight. QTL analyses revealed four loci for hard‐seededness and 11 loci for seed weight. Two of the hard‐seeded ness loci co‐localized with seed weight QTL. When seed weight was used as a covariate in the analysis of hard‐seededness from the field data, two of the four hard‐seeded QTL remained significant with the effect al one of these remaining unchanged. These results explain why retaining hard‐seededness in large seeded mungbean lines has been unsuccessful. The existence of a persistent locus, however. indicated that breeding large and persistently hard‐seeded varieties of mungbean may be possible.

A sporophytic self· incompatibility system, such as occurs in Carthamus jlavescens Spreng., was studied by computer simulation. Equilibrium gene frequencies in an infinite population were estimated for three-allele and six-allele systems and found to be independent of initial frequencies. In a species existing as a series of more or less isolated small populations genetic drift caused rapid loss of alleles. Maintenance of the S allele system was enhanced by increased population size, and particularly by migration, by which alleles lost from one local population could be re-introduced from adjacent populations. Hard seed carryover had a lesser effect.

Carthamus flavescens Spreng is an annual herbaceous weed, indigenous to the Middle East, and closely related to C. tinctorius L. (cultivated safflower). Inheritance of the following characters was found to be determined by a single gene each in interspecific crosses between these species: short vs. long rosette stage of growth, lobed vs. entire leaf margins, shattering vs. nonshattering of the achenes, white vs. pigmented achenes, presence vs. absence of pappus, and purple vs. green midveins of the cotyledonary leaves. The role of C. flavescens in the evolution of cultivated safflower is discussed.

S U M M A R Y Time to flowering of mung bean crops varies appreciably depending on the genotype, and the daylengths and temperatures prevailing during the period after sowing. Relatively little is known about the precise nature and inheritance of flowering responses to photoperiod and temperature. The combined effects of variations in these two factors on time to flowering were therefore evaluated in controlled environment studies on six genotypes and four F, hybrids. The responses were examined for conformity with hypothesized linear models from which inferences might be made of the genetic control of flowering. The analyses suggest that all the genotypes and F,s tested were quantitative short day plants, with the possible exception of one line which may be day neutral. The analyses further suggest that time to flowering was influenced by four genotype-specific attributes: minimum time to flowering, critical photoperiod (Pc), responsiveness to photoperiod longer than Pc, and responsiveness to temperature. Among the genotypes tested, different values were observed for each attribute. In most instances, the values for the F,s were closer to one or other parent, indicating dominance rather than additive genetic effects. We conclude that, with several levels each, the four attributes provide the potential for a diversity of flowering response types within mung bean. Further, it should prove possible to manipulate the mung bean germplasm to obtain novel combinations of attributes, and thus to breed genotypes adapted to photothermal regimes not previously considered suitable for the crop.B. C. Imrie y R. J. Lawn: Intervalo hasta la flotation en genotipos de frijol mungo (Vigna radiata) y sits hibridos en funcion del fotoperiodo y la temperatura. RESUMENEl intervalo hasta la floracion de cultivos de frijol mungo vari'a de forma apreciable segun el genotipo y las duraciones de los di'as y las temperaturas reinantes durante el pen'odo posterior a la siembra. Se conoce relativamente poco de la naturaleza exacta y la herencia de las respuestas de floracion ante el fotoperiodo y la temperatura; por tanto se evaluaron los efectos combinados de variaciones en esto dos factores sobre el intervalo hasta la floracion en estudios de entorno controlado en seis genotipos y cuatro hibridos F,. Se analizaron las respuestas para comprobar su conformidad con los modelos lineales hipoteticos, en base a los cuales se podrian deducir inferencias sobre el control genetico de la floracion. Los analisis indican ademas que el intervalo hasta la floracion se ve afectado por cuatro atributos especi'ficos al genotipo: el intervalo minimo hasta la floracion, el fotopen'odo critico (Pc), la sensibilidad al fotoperiodo superior al Pc, y las sensibilidad a la temperatura. Entre los genotipos usados para los ensayos, se observaron diferentes valores para cada atributo. En la mayon'a de los casos los valores para los F,s fueron mas proximos a uno u otro de los padres, lo cual indica mas bien una dominacion y no efectos geneticos sumados. Se Uego a la ...

Two genetic linkage maps of mungbean derived from the cross Berken ACC 41 are reported. The F2 map constructed from 67 individuals consisted of 110 markers (52 RFLP and 56 RAPD) that grouped into 12 linkage groups. The linked markers spanned a total map distance of 758.3 cM. A recombinant inbred (RI) population derived from the 67 F2 individuals was used for the generation of an additional linkage map. The RI map, composed entirely of RAPD markers, consisted of 115 markers in 12 linkage groups. The linked markers spanned a total map distance of 691.7 cM. Using a framework set of RFLP markers, the F2 map was compared with another F2 mungbean map constructed in Minnesota. In general, the order of these markers was consistent between maps. Segregation distortion was observed for some markers. 14.5% (16/110) of mapped F2 markers and 24% (28/115) of mapped RI markers segregated with distorted ratios. Segregation distortion occurred in each successive generation after the F2 . The regions of distortion identified in the Australian maps did not coincide with regions of the Minnesota map.