Peanuts: gibberellin antagonists and genetically controlled differences in growth habit.

Treatment of peanuts with gibberellin changed the orientation of lateral branches of runners to that of erect ones, and two growth retardants changed those of the erect type to a more horizontal orientation. Little or no difference was found in amounts of endogenous gibberellin in the two types of plants, but amount of native gibberellic acid antagonists was higher in runner plants. Furthermore, runner plants contained a particular gibberellic acid inhibitor not found in erect plants. Applications of various auxins, antiauxins, and a cytokinin had no effect on tropistic growth of the side branches.

Inheritance of Resistance to Fusarium Wilt in Sweet Basil.

Fusarium wilt, caused by Fusarium oxysporum f. sp. bacilici, is a severe disease of sweet basil (Ocimum basilicum L.) and has become acute mainly due to the intensive monoculture in green-houses and, recently, to prohibition of methyl bromide application. In a previous work, we selected a resistant cultivar, Nufar, to address this problem. The mode of inheritance of resistance to F. oxysporum f. sp. bacilici in sweet basil was examined in progenies derived from crosses of the homogeneous resistant cv. Nufar and the susceptible homogenous cv. Chen. Artificial inoculation of seedlings with a high concentration of a microconidial suspension of a virulent isolate of F. oxysporum f. sp. bacilici revealed no difference between reciprocal backcrosses. The nuclear resistance analysis and dominant characteristics of the resistance of backcross progenies of different parental lines and the segregation for resistance in F2 combinations fitted the expected Mendelian ratio for a single dominant gene with two alleles that confer resistance to Fusarium wilt in basil. These results indicate the usefulness of utilizing this resistance to F. oxysporum f.sp. bacilici in the production of new hybrids and cultivars of basil.

Plasmon divergence in peanuts (Arachis hypogaea): A third plasmon and locus affecting growth habit.

In a series of reciprocal crosses between peanut (Arachis hypogaea L.) cultivars from different regions and known testers, the cultivar HG1 from India was shown to have a third plasmon type, designated [G]. HG1 also has a third locus, Hb5 , which interacts with the plasmons and the loci described earlier. In the [G] plasmon, Hb1 and Hb5 are additive: plants having three or four dominant alleles have a trailing habit while the other nuclear genotypes produce in [G] erect plants. In the [V4] plasmon, Hb2 and Hb5 are complementary, [V4] Hb2-, Hb5-plants being trailing, the others erect. In the [G] plasmon, Hb2 and Hb5 are complementary, while in the [O] plasmon they are additive.

Detection of genic interactions by analyzing the F2 generation of diallel crosses.

The ability of the Hayman and Jinks method of analysis of diallel crosses to detect genic interactions was studied in peanuts. Six traits, measured in the F2 generation of a diallel cross of four cultivars, were analyzed. In F2 analyses of the diallel, least squares estimates of variance components D, H1 , H2, F, E, were used as an additional criteria for the adequacy of the diallel model. They were found to be in substantial agreement with the tests based on Wr and Vr values, and probably more reliable. The regression of Wr on Vr was shown to be unsuitable to detect 'duplicate gene' type of interactions; it was detected, however, by the ratio of the mean within-F2 - family variance and the variance among the parents. Using the different criteria, 'duplicate genes' type of interactions was detected for two traits, 'complementary genes' type was detected for one trait and three traits were found to fit the additive-dominance model without any genic interactions.

A simple rapid photometric estimation of the growth response of immobilized cells to fusaric acid and gamma radiation.

A simple and rapid photometric method was developed in order to evaluate the growth responses of cells to various factors in vitro. Cells of Asparagus officinalis L. were mixed with autoclaved agar at 40°C and 90 µl drops were dispensed into several Petri dishes. After the drops solidified, they were covered with a liquid growth medium and incubated on a gyratory shaker. Growth was measured every 2 or 3 days by two methods. In the first, the agar drop was placed under a stereomicroscope with substage illumination and the light passing through the embedded cells was measured by a light-meter. Growth, expressed by the increase in cell density, was inversely proportional to the intensity of transmitted light. In the second method, the agar drop was melted in a microwave oven and the packed cell volume was measured. The correlation between the two methods showed that the photometric method can be used to assess growth response of immobilized cells, during the first two weeks of culture. This method was used to evaluate growth responses to the toxin fusaric acid and to gamma radiation. The photometric method requires a small amount of inoculum, standard microscopic equipment and can be used to determine the effect of various factors on the growth of intact plant cells in vitro without disruption.

A 9 × 9 diallel analysis in peanuts (A. hypogaea L.): Flowering time, tops' weight, pod yield per plant and pod weight.

Four quantitative traits were studied by analysing F2 data derived from a 9 × 9 diallel cross utilizing widely divergent, inbred, erect cultivars of peanuts, A. hypogaea. Bidirectional dominance was found in the traits total pod yield per plant and number of days from planting to first flower; in pod size, the alleles giving small pods were consistently dominant and for high tops' weight, dominance and overdominance were found. The high heritability of pod yield/plant (0.79) indicates that breeding for higher yield/plant can succeed if large F2 populations are grown and rigorous visual selection combined with progeny testing are employed. The genetic correlations of pod yield/plant with other traits were low. Breeding for plants with large (jumbo) pods can be aided by the fact that they are homozygous recessive, or nearly so. Simultaneous breeding for high yields and large pods is possible: there was a positive (but low) genetic correlation between the two (0.16). A modification by which less biased estimates of the number of effective factors can be obtained and a possible relationship between bidirectional dominance and genic interaction were proposed.

Evaluation of the germ plasm collection of safflower Carthamus tinctorius L. VI. Length of planting to flowering period and plant height in Israel, Utah and Washington.

Germ plasm collections of safflower, Carthamus tinctorius L. were evaluated for variability and divergence in two traits which are strongly influenced by the environment, viz. length of the growing period from planting to flowering (GPPF) and plant height. The test locations were: Bet-Dagan, Israel, 1969, about 2000 lines; Logan, Utah, USA, 1964, about 1000 lines; Washington, USA, 1959, 339 lines. Natural selection produced a wide range of variation for length of the GPPF: there were considerable differences between introductions from the same countries. Divergence between lines within countries for GPPF length was so extensive that there was little evident divergence between regions. Generally lines from the Indian subcontinent, Egypt, Morocco, Spain, Portugal and France were earlier, while those from Turkey and Ethiopia were later. Some significant but inconsistent correlations were obtained between the length of the GPPF and other traits measured in Utah. It was not significantly correlated with yield and yield components or with oil content. Therefore, selection can be applied for a shorter GPPF without effecting yield or oil content.Plant height variations between lines from the same countries were very high in all test locations, still divergence between regions was apparent. The means of the lines from the Indian subcontinent were the lowest while those of the lines from Iran, Afghanistan, Turkey and Ethiopia were the highest in all the locations tested. Plant height was not correlated significantly with yield/plant and yield components in the Indian and Egyptian lines, and with yield and some components in the Iranian lines. Therefore, it appears possible to breed shorter, high yielding varieties.The correlations of GPPF and of plant height between test locations though low, were highly significant. Generally, the lines maintained their developmental pattern (early vs. late, short vs. tall) in the different nurseries, but there were position changes within the groups.