No abstract

Kretzschmaria zonata (Lév.) P.M.D. Martin is a fungus that causes root and neck rot in teak (Tectona grandis L.) worldwide. The detection of this fungus in asymptomatic plants is essential for its control but, to date, the disease can only be detected morphologically or by sequencing this fungus’s isolates. The aim of this work was to design, at least, one set of specific PCR primers for a quickly, early and accurate diagnosis of this pathogen. Nineteen isolates of K. zonata from teak plants at different locations in Mexico were obtained. ITS region sequences and two software were used to design the PCR-based primers. All primers obtained were tested on DNA samples from infected teak tissue, K. zonata pure isolates, and other different fungi species (in vitro and in silico). The sensitivity of the primers was evaluated at five different concentrations of target DNA. The primer set KZ-AQ-3F/KZ-AQ-3R was selected for its specificity (amplifies only K. zonata) and sensitivity (1 × 10−5 ng/µL detection). This is the first report of a Kretzschmaria zonata-specific primer set. Tests carried out on asymptomatic teak and artificially inoculated plants with this fungus demonstrated the usefulness of these primers for the accurate detection of K. zonata, and taking early control measures.

The genus Eucalyptus has shown great potential for the establishment of commercial forest plantations, it is one of the most widely planted worldwide, it is planted in different regions of the planet, which indicates its ability to adapt to various environmental conditions. Eucalyptus urophylla is a species of this genus that adapts to tropical and subtropical regions, in suitable sites it can achieve high growth rates. It is one of the species with the most research in breeding programs in the world, mainly due to its capacity to hybridize naturally, since it generates populations with high genetic diversity, coupled with its ability to reproduce asexually. In Mexico, the breeding programs for Eucalyptus urophylla are in the initial phase, although plantations are already managed under clonal silviculture, controlled crossing are just beginning, so pollen management and crossing techniques are the most important activities in these programs. Since there is currently no information about the management of pollen for Eucalyptus urophylla in Mexico, the aim of this paper is to show a methodology based on the information documented in other parts of the world and the recent experience acquired in the collection and management of pollen, as well as the controlled pollination techniques recently employed in the breeding programs of Eucalyptus urophylla in southeastern Mexico.

The aim of this work was to evaluate the basic density of wood from candidate clones of Eucalyptus urophylla, in Huimanguillo, Tabasco. Eleven different genotypes of five and 12 years old were studied. Two methodologies were used, the empirical method and by water displacement. The density of wood in the genotypes ranged from 0.38 to 0.63 g cm-3 which is catalogued as light to very light. The variation in basic density between clones and the methodologies used was not significant.

Six leguminous species Frijol bayo (Vigna unguiculata), Frijol white Var. Orituco, Quinchoncho dwarf (Cajanus cajan (L.) Millsp., cv. Aroita), Kudzú tropical (Pueraria phaseoloides), Crotalaria (Crotalaria juncea), Sesbania (Sesbania grandiflora) were established in an agroforest systems to assess his effect on the chemical property of a Alfisol soil at municipality Ospino Portuguese state, at the farm La Yaguara planted with E. urograndis. In a design in random blocks with 7 processings and 4 repetitions, employing STATIXTIS 9.0 to carry out the ANDEVA and for variables where differences are presented the test was employed of Tukey (5%); obtaining as results that in the soil of the farm The Yaguara alone significant differences were found (P<0,05) for the variables relation C/N, CO, Zn, highly significant and differences (P<0,01)for N; being the Sesbania and quinchoncho the best treatment in relation C/N; for CO the frijol blanco and the treatment control; for Zn the quinchoncho and treatment control, frijol blanco and kudzú tropical; in the N quinchoncho and Sesbania. To confirm the generated profit to the agroforestry system analysis were completed foliate to the eucalyptus, finding highly significant differences for P with Frijol blanco and Kudzú and significant for Zn where is quinchoncho and treatment control.