Four barley varieties and four F8 lines derived by divergent selection for culm length were studied for a number of anatomical characteristics of the culm. Significant differences were observed in length and width of epidermal cells, culm thickness, thickness of sclerenchyma, and thickness of sclerenchyma cell walls. Except for the thickness of the sclerenchyma cell walls, the differences in the anatomical characteristics of the culm were not correlated with those in culm length caused by selection. Although it was not possible to determine the genetic basis of the association between culm length and thickness of the sclerenchyma cell walls because of the type of material used, this result does have implications in relation to breeding for lodging resistance. It is suggested that a higher lodging resistance could be obtained by combining in the same genotype a short culm with thick-walled sclerenchyma cells.
In some sites of Central Italy wild sunflowers are spreading from marginal areas into cropped fields. Crops like maize, tomato, tobacco, alfalfa are often infested with wild sunflowers. Hybrid sunflower crops are also infested with wild material. Plants and populations of wild sunflower also spontaneously grow at the edge of the fields, and along the ditches and roads. We have observed that wild sunflower is partially dispersed by its seed, but possibly it can propagate vegetatively by its perennial basal stalk when it survives the mild winter seasons. We have evidence that sunflower seeds maintain germination capacity for years after being plowed into the soil. This wild sunflower phenotypically resembles H. annuus, but the strong root system is not usual for an annual sunflower species. Concerning its origin, we observed variations indicating naturalization by either an introgression process involving wild species or a segregation of a hybrid variety and the enrichment of genes conferring seed dispersion and root persistence. It is possible that a similar process occurred a few centuries ago, after its introduction to Europe when sunflower escaped botanical gardens and began to colonize Eastern European areas.
It is well known that forecasting the flowering time of wild vegetation is useful for various sectors of human activity, particularly for all agricultural practices. Therefore, continuing previous work by Cenci et al., we will present here three new phenoclimatic models of the flowering time for a set of wild species, based on an original data sample of flowering dates for more than 500 species, observed at Guidonia (42 degrees N in central Italy) by Montelucci in the period 1960-1982. However, on applying the bootstrap technique to each species sample to check its basic statistical parameters, we found only about 200 to have data samples with an approximately Gaussian distribution. Eventually only 57 species (subdivided into eight monthly subsets from February to September) were used to formulate the models satisfactorily. The flowering date (represented by the z variable), is expressed in terms of two variables x and y by a nonlinear equation of the form z=axbeta+gammay. The x variable represents either the degree-day sum (in model 1), or the daily-maximum-temperature sum (in model 2), or the daily-global-insolation sum (in model 3), while y for all three models corresponds to the rainy-day sum. Note that all summations involved in the computation of the variables x and y take place over a certain period of time (preceding the flowering phase), which is a parameter to be determined by the fitting procedure. This parameter, together with the threshold temperature (needed to compute the degree-days in model 1), represents the two implicit parameters of the process, thus the total number of parameters (including these last two) becomes respectively, five for model 1, and four for the other two models. The preliminary results of this work were reported at the XVI International Botanical Congress (1-7 August 1999, St. Louis, Missouri USA).
Culture conditions have been established for callus induction and growth from different explants in L. angustissimus L. Calli were obtained from hypocotyls, leaves, stems, cotyledons and roots cultured on media containing 2,4-dichlorophenoxyacetic acid or c~-naphthaleneacetic acid with kinetin, N 6 -A2-isopentenyladenine or benzyladenine in different combinations and concentrations. Only those calli induced in presence of c~-naphthaleneacetic acid with benzyladenine or kinetin produced shoots. Calli induced from hypocotyl explants were the most efficient in regeneration of shoots. Transformation with an Agrobacterium rhizogenes binary vector carrying the plasmid pBI 121.1 is reported. The percentage of cotransformation was estimated by testing GUS activity in hairy roots. The integration of Ri T-DNA and the NPTII gene in transformed plants was confirmed by molecular analyses and in vitro culture of transgenic tissues in the presence of kanamycin.Abbreviations: BA -benzyladenine; 2,4-D -2
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