Maria Teresa Schifino Wittmann

Poliembrionia e número de sementes por fruto de quatro cultivares de tangerineira

Four mandarin cultivars were characterized for seed number per fruit and polyembryony, three of them are used as parents in the Departamento de Horticultura e Silvicultura - Universidade Federal do Rio Grande do Sul citrus breeding program. Mandarin fruits were sampled from the Experimental Station citrus collection, in Eldorado do Sul, RS, and their seeds were extracted and counted. In esterile chamber, the embryos were excised from seeds and cultured in vitro on MT medium (Murashige & Tucker, 1962), at 26±3°C with a 16h photoperiod. The mandarin cultivars Cai, Montenegrina (Citrus deliciosa Tenore), Ponca (C. reticulata Blanco) and King (C. nobilis Loureiro) had an average of 16, 14, 8 and 24 viable seeds per fruit, respectively, and 5.7, 5.7, 7.7 and 3.2 embryos per seed. Monoembryonyc seed production was low, except in King cultivar, which had 20.4% of monoembryonic seeds. Albine embryos were also detected, which were part or total content of some seeds. In general, the species showed significant differences in relation to the studied traits. The similarities between the C. deliciosa cultivars are strong evidences for the hipotesis that Montenegrina is originated from Cai.

Tolerância ao frio e caracterização de híbridos entre leucaena leucocephala e L. diversifolia

The objective of this experiment was to identify material to be used as an alternative forage in the conditions of Southern Brazil. A population of hybrids between L. leucocephala and L. diversifolia (both tetraploid species, with 2n=104 chromosomes) in advanced generations was evaluated. The rate of growth in height, duration of flowering and frutification, number of flowers and legumes per inflorescence, seeds per legume, cold tolerance (expressed as foliage retention during winter) and regrowth ability in early spring were evaluated. A great intrapopulational variability was detected for all evaluated characteristics. Some individuals allying cold tolerance and desirable characteristics were identified to be used for further selection and breeding, which confirms the potentiality of Leucaena as a forage for Southern Brazil.

BIOLOGIA FLORAL E VIABILIDADE DE PÓLEN EM CULTIVARES DE CAQUIZEIRO (Diospyros kaki L.) E Diospyros virginiania L.

Persimmon tree is a very complex plant regarding floral biology, because it can present three types of flower (female, male or hermaphrodite) or only female as in the commercial cultivars. The objective of this research was to study the flowering period, flower types and to estimate pollen grains viability in nine D. kaki cultivars and in D. virginiana. Cultivars Pomelo and Rama Forte were the earliest for flowering beginning. Cultivar Pomelo and D. virginiana produced male flowers with viable pollen. The nine studied D. kaki cultivars presented females flowers (also male in Pomelo) as expected in commercial cultivars. Unexpectedly, cultivar Mikado presented male flowers with viable pollen at the end of the flowering period, what had not been previously reported. Pollen viability was generally over 90% for Pomelo, Mikado and D. virginiana.