Biometric assessment of early stem growth at a commercial stand of African mahogany (Khaya grandifoliola)

African mahogany species (Khaya spp.) have proven to be promising in the Brazilian forestry scenario, replacing native mahogany owing to their medium-fast growth and relevant timber value. This study aimed to carry out forest inventory and assessments of a Khaya grandifoliola plantation in the first years after planting, test hypsometric models to describe tree growth, and identify the maximum commercial stem yield (i.e., greater than 6 m in height). The stand was located in the municipality of Piracanjuba (GO), where seedlings of seed origin were used. Twenty random plots with a 15 m radius were allocated, and the total height (HT), stem height (HS), diameter at breast height (DBH), crown area, and forest canopy were measured. Four hypsometric models were employed in this study. The best equation was selected based on determination coefficients and standard errors. Further, the models were cross-validated to evaluate predictability and bias. At four years of planting, the largest class of HS was found to range from 3.1 to 4.1 m, and most trees had a DBH ranging from 0.084 to 0.126 m. The percentage of trees with stems > 6 m was 8.35%. The linear model ensured more consistent results for estimating HT, while the quadratic and Weibull models led to more consistent results for HS. By using models, stem measurements can be measured based on DBH, ultimately aiding the selection of stem management strategies for the growth of forests with greater commercial value.

Modified protocol to overcome in vitro recalcitrance of premature micro-shoots abscission by silver supplementation in Kinnow mandarin (Citrus nobilis L. × Citrus deliciosa T.)

The present study focused on alleviating the issue of premature abscission of micro-shoots emerged from the cultured nodal segments in Kinnow mandarin. To resolve the problem, explants of different maturity stages, culture media, growth regulator combinations and ethylene inhibitors (silver compounds) were evaluated. Hardwood stage was observed to be the most efficient explant maturity stage to boost the vigorous early shoot emergence on MS (Murashige and Skoog) medium. Addition of GA3 (Gibberellic acid) 10 mg L?1 resulted in delayed abscission. Further reduction in abscission rate and healthy shoot growth were observed when subculturing of micro-shoots was done on MS medium supplemented with BAP 2.5 mg L?1, GA3 10 mg L?1 and silver thiosulfate 5 mg L?1. This modified procedure could be effectively utilized for mass multiplication as well as crop improvement in Kinnow mandarin.

Observation of Soft-Rot Wood Degradation Caused by Higher Ascomyceteous fungi

The capability of higher ascomyceteous fungi to cause typical soft-rot decay for wood under laboratory conditions is reviewed and discussed. Fungi tested were extremely active in the decomposition of timbers. Scanning electron micrographs illustrated typical soft-rot decay pattern of higher wood decay ascomycetes, with the exception of H. trugodes that caused white-rot decay. Most of the fungi tested could be grouped as soft-rot fungi that showed typical soft-rot type II. Hypha confined primarily to the resin canals in softwoods or vessel elements in hardwoods and spread tracheid to tracheid via pits of cell wall to cell wall with mechanical force.