Changes in fineroot growth dynamics in response to phosphorus application in an Acacia mangium plantation in Vietnam

Fineroots (≤ 2 mm diameter) are dynamic components of the forest ecosystems and play important role in water and nutrient acquisition in forests. These roots are sensitive to forest fertilization and therefore, the response of fineroots to nutrient application would provide better understanding of the forest carbon and nutrient dynamics that will be helpful in sustainable forest management plans. Two fertilization treatments, including (1) F400: 400 g P₂O₅ (16.5%)/tree and (2) F600: 600 g P₂O₅ /tree, and F0: control (without fertilization), were applied in an Acacia mangium plantation with a planting density of 1100 trees/ha (3 m?×?3 m). The evaluation of fineroot growth across seasons showed that fertilization significantly increased production and subsequent mortality and decomposition. The total decomposition associated with F600 application was 7.95 tons ha^?1 year^?1, equaling 121% of F400 and 160% of the control. Mortality in F600 was 8.75 tons ha^?1 year^?1, equaling 111% of F400 and 198% of F0, while production in F600 was 10.40 tons ha^?1 year^?1, equaling 127% of F400 and 143% of F0. Fineroot production, mortality, and decomposition are seasonally dependent, with higher values measured in the rainy season than in the dry season. Stand basal area increment was significantly correlated with fineroot production (R²?=?0.75), mortality (R²?=?0.44), and decomposition (R²?=?0.48). This study showed that fertilization could facilitate fineroot production, which can then lead to a higher turnover of carbon and nutrients through the decomposition of the greater mass of the fineroots.

     

Determination of spermatological properties of male Liza abu (Heckel, 1843) in Atatürk Dam Lake, Şanlıurfa

The aim of this study was to determine the spermatological characteristics in male L. abu during the spawning season. Semen was collected weekly by abdominal massage from 26 males in March. In collected semen, volume, motility, duration of motility, concentration and pH were determined. In the L. abu sperm, volume (μl), motility (%), duration of motility (s), concentration (×10⁹/ml), and pH values were found 45.76 ± 3.55, 54.25 ± 2.93, 330.15 ± 37.92, 4.27 ± 0.40 and 7.87 ± 0.05, respectively. A correlation was found between semen volume and semen pH. Semen volume and the duration of sperm motility were higher in the 2nd and 3rd sampling dates than in the 1st and 4th sampling dates (P < 0.05; P < 0.01, respectively). Neither sperm motility nor sperm concentration was affected by sampling dates. Major changes in semen pH were observed in the 4th sampling date (P < 0.001). The Pearson correlation test presented significant relationships with the duration of motility, semen volume, and motility. Semen pH values were significantly correlated with the sperm concentration and semen volume. Sperm concentration was inversely correlated with semen volume. Sperm motility and duration significantly correlated with total weight. Total length significantly correlated with the duration of motility and total weight. In conclusion, these characteristics represent a valuable baseline dataset for establishing a semen quality standard and provide background information that may be useful for assisted breeding programs in this species.     

Freezing and Frost Damage of Potato Plants: a Case Study on Growth Recovery,Yield Response,and Quality Changes

The relationship between the severity of natural freezing and frost damage (FFD) and the observed growth recovery and field production of Superior potatoes (Solanum tuberosum L.) was investigated under screen house conditions. Potato plants were damaged by accidental freezing and frost during the early phase of shoot growth, 40 days after planting in highland summer crop areas in Korea. The observations of FFD were classified visually into “severe” (>75%), “moderate” (50%), “mild” (<25%), and “no FFD”, based on the percentage of the area of the shoots which was damaged. The early vegetative growth recovery, in terms of groundcover, was reduced as the level of FFD increased. At 28 days after a freezing and frost damage (DAFF), the potato plants with mild or no symptoms had produced more groundcover than the plants with moderate or severe symptoms. At 35 DAFF, groundcover was the same across all levels of severity, at nearly 100%. Despite the slower canopy development, plants with FFD achieved a higher fresh shoot weight and total chlorophyll content, whereas physiological growth indices such as photosynthetic rate and stomatal conductance of leaves were not different among levels of FFD at 60 DAFF. The number of lateral stems and days to tuberization increased significantly as the level of FFD increased; however, the harvest index, the number of tubers per plant, and seed tuber production were all reduced in plants with severe FFD. In addition, the tubers from plants with severe FFD had an increased ratio of length to width and 40% more tuber eyes than tubers from undamaged plants. The elongated tubers also showed an increase in cell division, demonstrated by higher numbers of cells in the cortical zones. The aforementioned measurements were obtained from natural event and led to a deduction that Superior has a capacity to recover from FFD, unless the plants were severely damaged (>75%) early in the season.     

Molecular cloning and characterization of a novel 1-aminocyclopropane-1-carboxylate oxidase gene involved in ripening of banana fruits

One novel banana fruit ripening related 1-aminocyclopropane-1-carboxylate (ACC) oxidase gene quite different from ACC oxidase genes from other species was cloned. In contrast to other studies, the polypeptide encoded by this gene, named Mh-ACO1, lacks the putative leucine zipper motif which is conserved in all known ACC oxidases including the other previously reported banana ACC oxidase, Mh-ACO2. The locus consists of two nearly identical paralogous ACC oxidase genes arranged in opposite orientation and separated by a 3.1-kb intergenic region. The has only two introns, at positions identical to , which comprises a coding region interrupted by three introns. The predicted amino acid sequence of Mh-ACO1 shares less than 50% identity to those of ACC oxidase from other climacteric fruits, while that of Mh-ACO2 shows more than 65% homology. When expressed in Saccharomyces cerevisiae -encoded protein possessed the enzyme activity for ethylene conversion. The levels of mRNA corresponding to both and increased during fruit ripening and were induced by exogenous ethylene. We conclude that both and contribute to increased ethylene production in fruits and these two genes are differentially expressed in fruits and other organs in banana.     

Preparation of poly(vinyl acetate)/clay and poly(vinyl acetate)/poly(vinyl alcohol)/clay microspheres

Poly(vinyl acetate) (PVAc)/poly(vinyl alcohol)(PVA)/montmorillonite (MMT) clay nanocomposite microspheres with a core/shell structure have been developed via a suspension polymerization approach. In order to prepare the PVAc/MMT and PVAc/PVA/MMT nanocomposite microspheres, which are promising precursor of PVA/MMT nanocomposite microspheres, suspension polymerization of vinyl acetate with organophilic MMT and heterogeneous saponification were conducted. A quaternary ammonium salt, cetyltrimethylammonium bromide, was mixed with the MMT in the monomer phase prior to the suspension polymerization. The rate of conversion decreased with an increase in MMT concentration. The incorporation of MMT into the PVAc was verified by FT-IR spectroscopy. Organic vinyl acetate monomers were intercalated into the interlayer regions of organophilic clay hosts and followed by suspension polymerization. Partially saponified PVA/MMT nanocomposite microspheres with a core/shell structure were successfully prepared by heterogeneous saponification.     

A hybrid swarm population of Pinus densiflora × P. sylvestris inferred from sequence analysis of chloroplast DNA and morphological characters

To confirm a hybrid swarm population of Pinus densiflora × P. sylvestris in Jilin, China, we used needles and seeds from P. densiflora, P. sylvestris, and P. densiflora × P. sylvestris collected from natural stands or experimental stations to study whether shoot apex morphology of 4- year old seedlings can be correlated with the sequence of a chloroplast DNA simple sequence repeat marker (cpDNA SSRs). Total genomic DNA was extracted and subjected to sequence analysis of the pine cpDNA SSR marker Pt15169. Results show that morphological characters from 4-year old seedlings did not correlate with sequence variants of this marker. Marker haplotypes from all P. sylvestris trees had a CTAT element that was absent from all sampled P. densiflora trees. However, both haplotype classes involving this insertion/deletion element were found in a P. densiflora × P. sylvestris population and its seedling progeny. It was concluded that the P. densiflora × P. sylvestris accessions sampled from Jilin, China resulted from bi-directional crosses, as evidenced by both species’ cpDNA haplotypes within the hybrid swarm population.     

Assessment of genetic diversity and population structure of Vietnamese indigenous cattle populations by microsatellites

Cattle play a very important role in agriculture and food security in Vietnam. A high level of cattle diversity exists and serves different needs of Vietnamese cattle keepers but has not yet been molecularly characterized. This study evaluates the genetic diversity and structure of Vietnamese indigenous cattle populations, using microsatellite markers. A total of 410 individuals from six indigenous cattle populations and an exotic breed was characterized using 27 microsatellite markers A total of 362 alleles was detected and the number of alleles per locus ranged from 8 (INRA005 and ILSTS005) to 17 (ETH185). The level of gene diversity was high indicated by a mean expected heterozygosity (He) across populations and loci of 0.73. Level of inbreeding (mean F_IS=0.05) and genetic differentiation (mean F_ST=0.04) was moderate. The phylogenetic tree based on Reynolds genetic distance reflected geographic distances. Structure analysis indicated five homogeneous clusters. The Brahman, Lang Son, Ha Giang and U Dau Riu cattle were assigned to independent clusters while Nghe An, Thanh Hoa and Phu Yen cattle were grouped in a single cluster. We conclude that Vietnamese indigenous cattle have high levels of genetic diversity and distinct genetic structures. Based on these results, we recommend that for conservation homogenous populations (Nghe An, Thanh Hoa and Phu Yen) can be grouped to reduce costs and U Dau Riu, Lang Son and Ha Giang populations should be conserved separately to avoid loss of genetic diversity.     

Properties of waterborne polyurethane (WBPU) coatings: Effect of alkyl chain length of tertiary amines of carboxylic acid salt groups

Waterborne polyurethane (WBPU) dispersions were prepared via a pre-polymer process using 4,4-dicyclohexylmethane diisocyanate (H₁₂MDI), poly(tetramethyleneoxideglycol) (PTMG), 2,2-dimethylol propionic acid (DMPA), ethylene diamine (EDA), and tertiary amines (TAs) with varying amounts of DMPA and TAs. Three TAs with different alkyl chain lengths were used to neutralize the DMPA carboxylic group: N,N-dimethylbutylamine (DMBA, C4), N,N-dimethylhexylamine (DMHA, C6), and N,N-dimethyloctylamine (DMOA, C8). The structures of the synthesized WBPUs were determined via FT-IR and ¹H NMR spectroscopic techniques. The effects of DMPA and TA content and the TA alkyl chain length on stability of dispersions and properties such as water swelling (%), glass transition temperature (T _g ), tensile strength, binding energy and adhesive strength were investigated. The initial adhesive strength of the intact coatings increased with increasing DMPA and TA content and increasing alkyl chain length of TA. However, after immersion of the coatings in water, the adhesive strength decreased. The maximum adhesive strength under water was observed at a DMPA content of 20.20 mol% with 5.30 wt% DMOA, which has the longest alkyl chain.     

Root treatment with rhizobacteria antagonistic to Phytophthora blight affects anthracnose occurrence, ripening, and yield of pepper fruit in the plastic house and field

We previously selected rhizobacterial strains CCR04, CCR80, GSE09, ISE13, and ISE14, which were antagonistic to Phytophthora blight of pepper. In this study, we investigated the effects of root treatment of rhizobacteria on anthracnose occurrence, ripening, and yield of pepper fruit in the plastic house and field in 2008 and 2009. We also examined the effects of volatiles produced by the strains on fruit ripening and on mycelial growth and spore development of Colletotrichum acutatum and Phytophthora capsici in the laboratory, identifying the volatile compounds by gas chromatography-mass spectrometry (GC-MS). In the house tests, all strains significantly (P < 0.05) reduced anthracnose incidence on pepper fruit; strains GSE09 and ISE14 consistently produced higher numbers of pepper fruit or increased the fresh weight of red fruit more than the controls in both years. In the field tests, all strains significantly (P < 0.05) reduced anthracnose occurrence on either green or red pepper fruit; strain ISE14 consistently produced higher numbers or increased fresh weights of red fruit more than the controls in both years. In the laboratory tests, volatiles produced by strains GSE09 and ISE13 only stimulated maturation of pepper fruit from green (unripe) to red (ripe) fruit; the volatiles of certain strains inhibited the growth and development of C. acutatum and P. capsici. On the other hand, GC-MS analysis of volatiles of strains GSE09 and ISE13 revealed 17 distinct compounds in both strains, including decane, dodecane, 1,3-di-tert-butylbenzene, tetradecane, 2,4-di-tert-butylphenol, and hexadecane. Among these compounds, 2,4-di-tert-butylphenol only stimulated fruit ripening and inhibited growth and development of the pathogens. Taken together, strains GSE09 and ISE14 effectively reduced anthracnose occurrence and stimulated pepper fruit ripening and yield, possibly via bacterial volatiles. Therefore, these two strains could be potential agents for controlling Phytophthora blight and anthracnose, and for increasing fruit ripening and yield. To our knowledge, this is the first report of volatiles such as 2,4-di-tert-butylphenol produced by rhizobacteria being related to both fruit ripening and pathogen inhibition.