Collembolan community dynamics during deciduous forests regeneration in Japan

The structure and feeding group composition of collembolan communities were studied in secondary deciduous forests of different ages to investigate the collembolan community response to environmental changes associated with forest cycles. The study was carried out at eight sites forming a chronosequence (1, 4, 12, 24, 51, 54, 71 and 128 years after clear cutting) of deciduous forest stands in northern Ibaraki (Japan). Total collembolan density and species richness was low at the 1-year-old site, and there was little difference in density among sites over 4 years of age. The density of sucking feeders was especially low at the 1-year-old site. Species richness of trees of a diameter at breast height (DBH)<5 cm positively correlated with the density of fungal feeders. Species richness of total Collembolans and of sucking feeders correlated positively with the water content of the organic layer. Ordination of the collembolan community with Canonical Correspondence Analysis suggested that species richness of larger trees (DBH 5 cm) contributed to the differences in species composition of fungal feeders and sucking feeders. We conclude that total abundance and species richness of collembolans recovered within 4 years after clear-cutting, but species composition of fungal feeders and sucking feeders took longer to recover.     

Effects of co-inoculation of Bradyrhizobium elkanii BLY3-8 and Streptomyces griseoflavus P4 on Rj4 soybean varieties

Co-inoculation of selected nitrogen-fixing bacteria with plant growth-promoting bacteria is the promising way for the improvement of soybean production through enhancing plant growth, nodulation, and N₂ fixation. Therefore, this experiment was conducted to study the effects of co-inoculation of Bradyrhizobium elkanii BLY3-8 with Streptomyces griseoflavus P4 on plant growth, nodulation, N₂ fixation, N uptake, and seed yield of Rj₄ soybean varieties. Two experiments with completely randomized design and three replicates were done in this study. N₂-fixation ability of soybean was evaluated by acetylene reduction activity (ARA) and relative ureide method. In the first experiment, synergetic effect in N₂ fixation and nodulation was occurred in co-inoculation treatment (BLY3-8 + P4) in Yezin-3 and Fukuyutaka. Based on these results, co-inoculation effect of BLY3-8 and P4 was assessed on Yezin-3 and Fukuyutaka varieties at three different growth stages, using Futsukaichi soil under natural environmental conditions. This study shows that co-inoculation of BLY3-8 and P4 significantly increased N₂ fixation at V6 stage; plant growth, nodulation, N₂ fixation, and N uptake at R3.5 stage; and shoot growth, N uptake, and seed yield at R8 stage, in Rj₄ soybean varieties compared with the control. Significant difference in plant growth, nodulation, N₂ fixation, N uptake, and yield between co-inoculation and control, not between single inoculation and control, suggests that there is a synergetic effect due to co-inoculation of BLY3-8 and P4.     

Mapping the quantitative trait loci (QTL) for body shape and conformation measurements on BTA1 in Japanese Black cattle

The detection and mapping of segregating quantitative trait loci (QTL) that influence withers height, hip height, hip width, body length, chest width, chest depth, shoulder width, lumbar width, thurl width, pin bone width, rump length, cannon circumference, chest girth, abdominal width and abdominal girth at weaning was conducted on chromosomal regions of bovine chromosome one. The QTL analysis was performed by genotyping half‐sib progeny of five Japanese Black sires using microsatellite DNA markers. Probability coefficients of inheriting allele 1 or 2 from the sire at specific chromosomal locations were computed. The phenotypic data of progeny were regressed on these probability coefficients in a within‐common‐parent regression analysis using a linear model that included fixed effects of sex, parity and season of birth, as well as age as a covariate. F‐statistics were calculated every 1 cM on a linkage map. Permutation tests of 10 000 iterations were conducted to obtain chromosome‐wide significance thresholds. A significant QTL for chest width was detected at 91 cM in family 3. The detection of this QTL boosts the prospects of implementing marker‐assisted selection for body conformation traits in Japanese Black beef cattle.