Does orientation of raft helps in augmenting yield during lean period?: A case study of Gracilaria edulis cultivation in open sea by vertical raft alignment along the south-eastern coast of India

The food grade agar in India has been almost exclusively obtained from Gracilaria edulis, but the industrial production overwhelmingly relies on exploitation of natural resources. United Nations efforts through Food and Agriculture Organization under Bay of Bengal Program highlighted the necessity of undertaking commercial farming of this species along Indian coast for socio-economic benefits. The pilot-scale experiments established viability of large-scale cultivation by floating raft method. Nevertheless, drastic reduction in yield and quality during summer months due to enhanced sedimentation and severe epiphytism is found to be a major hindrance. Altering the positioning of rafts from horizontal to vertical alignment improved the growth and yield under open sea condition at two different locations along south east coast of India. The average yield in horizontal raft was found to be 3.08 ± 0.61 kg fr wt raft⁻¹ with corresponding DGR of 1.87 ± 0.63% day⁻¹ while same in case of vertical rafts was 13.76 ± 3.86 kg fr wt raft⁻¹ and 5.00 ± 0.5% day⁻¹ in Gulf of Mannar under 45 days growth cycle. The corresponding values along Palk Bay were 2.98 ± 0.52 g fr wt raft⁻¹ and 1.38 ± 0.42% day⁻¹ for horizontal raft and 13.02 ± 6.06 kg fr wt raft⁻¹ and 4.14 ± 1.18% day⁻¹ for vertical raft. ANOVA clearly indicated that raft position significantly influenced the biomass yield and DGR at Palk Bay (F = 75.77; F = 112.81) as well as Gulf of Mannar (F = 27.21; F = 59.16) at p = 0.001. The increment of 1.9–2.6% in fresh weight of individual frond was reported in vertically aligned rafts. The computational fluid dynamics (CFD) based unsteady numerical simulations have confirmed that vertical alignment of raft facilitates relatively free movement of water due to which sedimentation and epiphytism are either minimised or eliminated. Thus these studies can help us to deduce important conclusions pertaining to management of sustained commercial cultivation of this alga in Indian waters.     

Characterization of ethylene biosynthesis and its regulation during fruit ripening in kiwifruit,Actinidia chinensis ‘Sanuki Gold’

Ethylene biosynthesis in kiwifruit, Actinidia chinensis ‘Sanuki Gold’ was characterized using propylene, an ethylene analog, and 1-methylcyclopropene (1-MCP), an inhibitor of ethylene perception. In fruit harvested between a young stage (66 days after pollination) (DAP) and an early commercial harvesting stage (143 DAP), 2 days of exposure to propylene were sufficient to initiate ethylene biosynthesis while in fruit harvested at commercial harvesting stage (154 DAP), 4 days of propylene treatment were required. This observation suggests that response of ethylene biosynthesis to propylene treatment in kiwifruit declined with fruit maturity. Propylene treatment resulted in up-regulated expression of AC-ACO1, AC-ACO2, AC-SAM1 and AC-SAM2, prior to the induction of AC-ACS1 and ethylene production, confirming that AC-ACS1 is the rate limiting step in ethylene biosynthesis in kiwifruit. Treatment of fruit with more than 5 μL L^?1 of 1-MCP after the induction of ethylene production subsequently suppressed ethylene production and expression of ethylene biosynthesis genes. Treatment of fruit with 1-MCP at harvest followed with propylene treatment delayed the induction of ethylene production and AC-ACS1 expression for 5 days. These observations suggest that in ripening kiwifruit, ethylene biosynthesis is regulated by positive feedback mechanism and that 1-MCP treatment at harvest effectively delays ethylene production by 5 days.     

Induction of disease resistance against Botrytis cinerea by heat shock treatment in melon (Cucumis melo L.)

The present study investigated resistance against Botrytis cinerea after heat shock treatment in melon plants. Heat shock at 50 °C for 20 s 0–24 h before inoculation resulted in maximal B. cinerea symptom reduction and peroxidase gene expression, which peaked 12 and 72 h post-treatment and decreased 24–48 h post-treatment, suggesting pathogenesis-related protein expression priming. Hot water dipping did not directly inhibit mycelia growth. Plants treated with 2-benzisothiazol-3(2H)-one 1,1-dioxide, which induces systemic acquired resistance, demonstrated higher peroxidase gene expression but no B. cinerea resistance, indicating possible involvement of additional novel mechanisms in heat shock-activated resistance of melon against B. cinerea.     

Interaction of Cd-hyperaccumulator Solanum nigrum L. and functional endophyte Pseudomonas sp. Lk9 on soil heavy metals uptake

Bioaugmentation is a promising method for assisting phytoextraction of heavy metals from contaminated soil, and the development of bioaugmentation-assisted phytoextraction requires the understanding of the mechanism involved in the interaction between plants and inocula. In this study, a pot study was conducted to evaluate the effect of bacterial endophyte Pseudomonas sp. Lk9 which can produce biosurfactants, siderophores and organic acids on the growth and metal uptake of Cd-hyperaccumulator Solanum nigrum L. growing in multi-metal-contaminated soil. The results revealed that Lk9 inoculation could improve soil Fe and P mineral nutrition supplies, enhance soil heavy metal availability, and affect host-mediated low-molecular-weight organic acids secretion, thereby significantly increasing S. nigrum shoot dry biomass by 14% and the total of Cd by 46.6%, Zn by 16.4% and Cu by 16.0% accumulated in aerial parts, compared to those of non-inoculated control. The assessment of phytoextraction showed that Lk9 inoculation elevated the bioaccumulation factor of Cd (28.9%) and phytoextraction rates of all metals (17.4%, 48.6% and 104.6% for Cd, Zn and Cu, respectively), while the translocation factors had negligible difference between Lk9 inoculation (3.30, 0.50 and 0.40 for Cd, Zn and Cu, respectively) and non-inoculated control (2.95, 0.53 and 0.42 for Cd, Zn and Cu, respectively). It was also found that the symbiotic association between S. nigrum and Lk9 significantly increased the soil microbial biomass C by 39.2% and acid phosphatase activity by 28.6% compared to those in S. nigrum without Lk9. This study would provide a new insight into the bioaugmentation-assisted phytoextraction of heavy metal-contaminated soils.     

Response of ammonia oxidizing microbes to the stresses of arsenic and copper in two acidic alfisols

Soil pollution by elevated heavy metals exhibits adverse effects on soil microorganisms. Ammonia oxidizing bacteria and ammonia oxidizing archaea perform ammonia oxidative processes in acidic soils. However, influence of heavy metal stress on soil ammonia oxidizers distribution and diversity is inadequately addressed. This study investigated the responses of ammonia oxidizing bacteria and archaea to heavy metals, Cu and As during short-term laboratory experiment. Two different acidic alfisols named as Rayka and Hangzhou spiked with different concentrations of As, Cu and As + Cu were incubated for 10 weeks. Significant reduction in copy numbers of archaeal-16S rRNA, bacterial-16S rRNA and functional amoA genes was observed along elevated heavy metal concentrations. Ammonia oxidizing archaea was found to be more abundant than ammonia oxidizing bacteria in all the heavy metal treatments. The potential nitrification rate significantly decreased with increasing As and Cu concentrations in the two soils examined. Denaturing gradient gel electrophoresis analysis revealed no apparent community shift for ammonia oxidizing archaea even at higher concentrations of As and Cu. Phylogenetic analysis of archaeal amoA gene from 4 clone libraries indicated that all the archaeal amoA sequences were placed within 3 distinct clusters from soil and sediment group 1.1b of Thaumarchaeota. Our results could be useful for the better understanding of the ecological effects of heavy metals on the abundance and diversity of soil ammonia oxidizers.     

Development of a vision-based automatic vaccine injection system for flatfish

Traditionally, flatfish vaccination has been performed manually a laborious and time-consuming, procedure with low accuracy. The handling requirement also makes it prone to contamination. With a view to eliminating these drawbacks, we designed an automatic vaccine system in which the injection is delivered by a Cartesian coordinate robot (also called a linear robot) guided by a vision system. The automatic vaccine injection system is driven by an injection site location algorithm that uses a template-matching technique. The proposed algorithm was designed to derive the time and possible angles of injection by comparing a search area with a template. The algorithm is able to vaccinate various sizes of flatfish, even when they are loaded at different angles. We validated the performance of the proposed algorithm by analyzing the injection error according to randomly generated loading angles. The proposed algorithm allowed an injection rate of 2000 per hour on average. Vaccination of flatfish with a body length of up to 500 mm was possible, even when the orientation of the fish was random. The injection errors in various sizes of flatfish were very small, ranging from 0 to 0.6 mm.     

Surrounding pressure controlled by water table alters CO2 and CH4 fluxes in the littoral zone of a brackish-water lake

We studied the effect of water table on CO₂ and CH₄ fluxes at different time scales in the littoral zone of Lake Obuchi, a brackish lake in northern Japan. The vegetation formed three distinct zones along the water table gradient, two dominated by emergent aquatic macrophytes (the Phragmites australis-dominated zone and the Juncus yokoscensis-dominated zone) and one dominated by terrestrial macrophytes (Miscanthus sinensis and Cirsium inundatum-dominated zone). To clarify the impact of variations in water table on monthly and yearly summed CO₂ and CH₄ fluxes, we examined the relationship between water table and the ratio of observed flux to calculated flux, whereby the calculated flux was based solely on the exponential relationship between flux and soil temperature for each gas. This study revealed that the impact of variations in water table on monthly and yearly summed CO₂ and CH₄ fluxes differed markedly between the vegetation zones. By taking the temporal change in water table into account in the estimation of both the CO₂ and CH₄ fluxes, the monthly summed CO₂ and CH₄ fluxes in the Phragmites-zone were markedly greater in every month of the year compared to estimation based on temperature alone. In the Juncus-zone, the effect of water table on monthly summed CO₂ and CH₄ fluxes differed between months. In addition, the magnitude of water-table effects controlling monthly summed CO₂ and CH₄ fluxes differed with atmospheric conditions, i.e., between the pressure-falling and low-pressure phase on the one hand and other pressure phases on the other hand. After weighting all the impacts of temporal changes in water table on fluxes, the yearly summed CO₂ and CH₄ fluxes showed a 1.26–6.64-fold increase compared with not taking water table effects into account, and the increase differed among the three vegetation zones.     

In vitro regeneration from alginate-encapsulated microcuttings of Quercus sp.

Microcuttings with apical and nodal buds from common oak (Quercus robur L.) and Turkey oak (Quercus cerris L.) in vitro clones were encapsulated into an alginate matrix. Apical segments of common oak showed significantly greater in vitro regeneration potential as compared with the nodal ones. Encapsulated Turkey oak nodal segments demonstrated successful regeneration after different periods (2–6 weeks) of cold storage (4 °C), showing no significant deviation from the regenerative frequency of non-cold-treated segments.     

AFLP analysis of genetic diversity in low chill requiring walnut (Juglans regia L.) genotypes from Hatay,Turkey

In this study, the genetic relatedness of 22 low chill requiring walnut genotypes adapted to the south east Mediterranean region of Turkey was analysed by amplified fragment length polymorphism (AFLP) markers. Relatively low level of genetic variation was detected among the genotypes examined by five AFLP primer combinations, suggesting that these walnut genotypes selected predominantly for their low chill requirement have relatively narrow genetic base. In addition, the geographical proximity of the genotypes analysed was not correlated with their level of genetic relatedness. These results have implications for walnut breeding and conservation.