Cytogenetic characterization of the Passiflora edulis Sims x Passiflora cincinnata Mast. interspecific hybrid and its parents.

The genus Passiflora L. consists of approximately 530 widely distributed species, including Passiflora edulis, which has drawn interest because of its commercial and agronomic value. Passiflora cincinnata is another important species owing to its long flowering period and resistance or tolerance to diseases and pests. In the present study, the meiotic segregation and pollen viability of an interspecific hybrid (P. edulis x P. cincinnata) and its parents were analyzed. The genomic contents were characterized using chromomycin A3 (CMA3)/40-60-diamidino-2-phenylindole (DAPI) staining, fluorescent in situ hybridization with 5S/45S ribosomal DNA (rDNA), genomic in situ hybridization (GISH), and inter-simple sequence repeat (ISSR) markers. The results indicated the diploid chromosome number for the parents and interspecific hybrid was 2n = 18. We also observed regular meiosis, one pair of S rDNA sites, and two pairs of 45S rDNA sites that colocalized with two pairs of CMA3 /DAPI- bands. The GISH data revealed three distinct chromosomal groups in the hybrid. The genetic origins of the interspecific hybrid, and its relationship with its parents were also confirmed using ISSR markers.

Agronomic performance of selected sweet potato cultivars under greenhouse and field infested with meloigogyne incognita and soilborne insect pests.

The root knot nematode (RKN), Meloidogyne incognita, is widespread worldwide and a major pathogen of several cultivated crops. The use of resistant genotypes is the most effective and environmentally sound way to manage RKN. In this study, we screened 16 selected sweet potato cultivars including Amanda, Bárbara, Beatriz, Beauregard, Brazlândia Branca, Brazlândia Rosada, Brazlândia Roxa, BRS Amélia, BRS Cuia, BRS Rubissol, Carolina Vitória, Duda, Júlia, Marcela, PA-26/2009, and Princesa obtained from Embrapa and Universidade Federal do Tocantins? germplasm bank. Studies were conducted under greenhouse and field conditions and the agronomic performance of the cultivars was evaluated in a nematode and soilborne insect-infested field. All 16 sweet potato cultivars tested were rated as resistant to this nematode both under greenhouse and field conditions with reproduction factors < 1. In the field infested with M. incognita, sweet potato cultivars Duda, BRS Amélia, Beauregard, Brazlândia Rosada, and Brazlândia Roxa stood out as superior cultivars, with average yield ranging from 26 to 47 tons per ha. Overall, most cultivars exhibited a fusiform to near fusiform root shape, a good characteristic for the market, and were moderately affected by insects (attack incidence 1 to 30%). As global demand for energy continues to rise, selecting new cultivars of sweet potatoes with increased resistance to nematode diseases and with high yield will be important for food security and biofuel production.

Grafting compatibility among eleven chestnut cultivars and hybrids.

Among the four commercial chestnut species the C. dentata (Marsh.) Boskh. and C. sativa P. Mill. has excellent quality but more susceptible to diseases when compared to C. mollissima Blume and C. crenata Siebold & Zucc. which has inferior quality but can be used as rootstocks. This work aimed to evaluate the behavior of chestnut varieties grafted in different rootstocks under São Bento do Sapucaí, São Paulo, Brazil condition. In 1986, eleven chestnut cultivars and hybrids - Ibuki (IB), Izumo (IZ), Kinchu (KI), KM1 (KM2), KM(2) KM(2), Moriowase (MO), Okuni (OK), Taishowase (TAI), Tamatsukuri (TAM), Tiodowase (TIO) and Senri (SEN) (only graft) ? were grafted each other resulting in hundred ten combinations. Fifteen-year later grafted trees with minimum of three plants were evaluated for tree height, trunk diameter above and below graft union and graft compatibility. Randomized blocks with three replications were submitted to analysis of variance for tree height and trunk diameter. Grouping analysis using the PROC CLUSTER ? SAS system was used to describe the pattern of variance among different combinations. Seventy eight combinations in hundred ten showed perfect grafting compatibility 6 months after grafting. Forty seven combinations showed incompatibility after transplanting and the dieback rate in each combination ranged from 25 to 100%. Among seventy eight combinations established in the field twenty six had enough plants for evaluation fifteen-year later. Tree height and trunk diameter showed highly significant difference among the combinations. The highest plant (6 m) was grafted on Moriowase and Tamatsukuri which showed the highest compatibility as rootstock. The harvesting season is from November to May where MOR, IB, TAM, OK and TAI behave as early-season-cultivar and SEN the latest one.