Post Bloom Research Articles

Pelagic ecosystem dynamics between late autumn and the post spring bloom in a sub-Arctic fjord

Marine ecosystems, and particularly fjords, are experiencing an increasing level of human activity on a year-round basis, including the poorly studied winter period. To improve the knowledge base for environmentally sustainable management in all seasons, this study provides hydrographic and biological baseline data for the sub-Arctic fjord Kaldfjorden, Northern Norway (69.7° N, 18.7° E), between autumn 2017 and spring 2018. Field observations are integrated with results of a numerical ocean model simulation, illustrating how pelagic biomass, represented by chlorophyll a (Chl a), particulate organic carbon (POC), and zooplankton, is affected by stratification and circulation from October to May. We observed an unusually warm autumn that likely delayed the onset of cooling and may have supported the high abundances of holoplankton and meroplankton (5768 individuals m–3). With the onset of winter, the water column cooled and became vertically mixed, while suspended Chl a concentrations declined rapidly (< 0.12 mg Chl a m–3). In January and February, suspended POC concentrations and downward flux were elevated near the seafloor. The hydrodynamic model results indicate that the strongest currents at depth occurred in these months, potentially inducing resuspension events close to the seafloor. In spring (April), peak abundances of suspended biomass were observed (6.9–7.2 mg Chl a m–3 at 5–15 m; 9952 zooplankton ind. m–3 at 0–100 m), and field observations and model results suggest that zooplankton of Atlantic origin were probably advected into Kaldfjorden. During all investigated seasons, the model simulation suggests a complex circulation pattern, even in such a small fjord, which can have implications for environmental management of the fjord. We conclude that the pelagic system in Kaldfjorden changes continually from autumn to spring and that winter must be seen as a dynamic period, not a season where the fjord ecosystem is ‘at rest’.

Efficacy of Insecticides Against Jamun Seed Weevil Curculio c- album F.

Among seven insecticides evaluated azadirachtin 10000 ppm (1 ml/ l) was found to be the most effective against seed weevil Curculio c-album F., followed by deltamethrin 2.8EC (1.0 ml/ l) and malathion 50EC (2.0 ml/l). The least effective was spinosad 45SC (0.3 ml/ l) followed by cyantraniliprole 10.26OD (1.8 ml/ l). Three rounds of sprays (new flush, pre bloom and post bloom) of insecticides gave better protection when compared to single/ two sprays. Maximum healthy fruit yield (49.81 kg/ tree) was obtained with azadirachtin.

Earth Observation Techniques to Assess Water Quality Monitoring in the Murray Darling Basin of Australia

The Murray Darling Basin Authority (MDBA) currently has been using a discrete field sampling technique for water quality monitoring that is expensive, time consuming and may not adequately represent the spatial variability of water quality relative to the entire water body. A pilot project was executed to assess the effectiveness of using earth observation data, supported by archived field-based observations for quantitative estimation of Water Quality Parameters (WQP) and detection of algal blooms in the River Murray. The selected pilot study area includes a 100km stretch of the River Murray between the Hume Dam and Yarrawonga Weir. The time frame for the archived field samples was between November 2008 and March 2011, when major algal blooms were occurring in this stretch of the Murray River.Analysis of the 2009 data shows that waters in sites in the Murray River downstream of the Hume Dam to the Yarrawonga Weir show more temporal than spatial variability in Chl-a and PC levels. The Chl-a concentration is relatively less in the Yarrawonga Weir than in the Murray River. The scatter plot of PC vs. Turbidity suggests that PC is a more significant parameter for the detection of Cyanobacteria than Chl-a. The field data represents the temporal bio-optical variability across the 2009 algal bloom events by successfully capturing the co-variations among Chlorophyll-a, Chycocyanin and turbidity at pre, during and post bloom conditions. The methodology has proved that the usefulness of an integrated earth observation and field based WQP technique to accurately map algal bloom events. The long term MDBA RMWQMP data for the 2009 bloom event is found partially compatible to the NOW Pilot study data in that only the data for the Heywood site that was used together for testing the WQP monitoring technique. The incompatibility of the RMWQMP data downstream of Yarrawonga Weir may be due to differing techniques used for determining Chlorophyll. The 2010 data was suitable for testing the technique for complex spatial bio-optical variability during the peak of the bloom in a large water storage. Lack of Chlorophyll measurements in 2010 data poses challenges in interpreting the relationship of bio-optical variability with the spatial distributions of bio-optical parameters. As relational parameters are absent, local information and expert advice will be required to develop plausible assumptions between the Chlorophyll - Phycocyanin relationship. The field sampled data for the 2010 bloom event acquired from the Hume Dam was used for comparative investigation of both moderate resolution sensors (MODIS and MERIS) and high resolution sensors (TM/TM+). The 2009 bloom event field samples of sites in the Yarrawonga Weir was used as an input with MODIS and MERIS and the data from all the sites was applied with TM/TM+. This paper will present an integrated earth observation and field based WQP technique to accurately map algal bloom events, and discuss challenges for real time earth observation data initiatives and future collaborative projects.

Fruit quality of ‘Braeburn’ apple trees sprayed at post-bloom and preharvest with prohexadione-calcium and GA4+7

Abstract The objective of this study was to assess the effects of post-bloom (PB) or preharvest (PH) treatments of ‘Braeburn’ apple trees with prohexadione-calcium (ProCa; 300 mg L-1), an inhibitor of gibberellins biosynthesis, or GA4+7 (300 mg L-1) on fruit quality at harvest and after storage (four months at 0±0.5 oC, followed by five days of shelf life). PB treatments started 15 days after full bloom, with one application every week and six applications in total. PH treatments started five weeks before anticipated harvest, with one application every week and four applications in total. Control trees were sprayed with water. GA4+7 PB increased length/diameter ratio, and GA4+7 PH increased titratable acidity (TA) and flesh firmness and slightly reduced red color of the fruit at harvest. ProCa PB and PH reduced ethylene production rate, delayed starch degradation and reduced soluble solids content of the fruit at harvest, and ProCa PH maintained firmness at harvest and after storage and TA of the fruit after storage. ProCa PB or PH delayed the loss of skin green background color at harvest, while at both treatment timings reduced the development of skin red color, but with a much stronger effect when sprayed PH than PB.

Post bloom spraying apple trees with prohexadione-calcium and gibberellic acid affects vegetative growth, fruit mineral content and bitter pit incidence

This study was carried out to assess the effects of post bloom orchard spraying with ProCa and gibberellic acid (GA3) on vegetative growth, fruit mineral content and BP incidence.

Post-bloom and preharvest treatment of ‘Braeburn’ apple trees with prohexadione-calcium and GA4+7 affects vegetative growth and postharvest incidence of calcium-related physiological disorders and decay in the fruit

Calcium (Ca) deficiency disorders in apple fruit have been associated with high gibberellins (GAs) activity in the tree. This study was carried out to assess the effects of treatments of ‘Braeburn’ apple trees with prohexadione-calcium (ProCa, an inhibitor of GAs biosynthesis) or gibberellins (GA4+7) on vegetative growth of the trees and postharvest incidence of Ca-related physiological disorders and decay in the fruit. ProCa (300 mg L-1) or GA4+7 (300 mg L-1) treatments were applied post-bloom (PB) and preharvest (PH). PB treatments started 15 days after full bloom (DAFB), with one application every week and six applications in total. PH treatments started five weeks before anticipated harvest (125 DAFB), with one application every week and four applications in total. Control trees were left untreated. When applied PB, ProCa reduced and GA4+7 promoted vegetative growth of the trees. ProCa PB delayed the impairment of xylem functionality (at the proximal region of the fruit) during fruit growth on the tree. Treatments had no effect on fruit weight, pectinmethylesterase (PME) activity or the expression of CAX3, CAX6 and V-ATPase (transporters of Ca into the vacuole) genes assessed in the external cortical tissue at the distal end of the fruit at harvest. When sprayed PB, ProCa increased the total Ca content and reduced K/Ca, Mg/Ca, N/Ca, (Mg + K)/Ca and (K + Mg + N)/Ca ratios in the flesh at the distal portion of the fruit, compared to the treatment with GA4+7, but without differing from the control. In general, ProCa application PB or PH reduced the expression of Ca-ATPase1, Ca-ATPase2, H+-PPase and CAX2 (Ca transporters into the vacuole) genes, increased total water‐soluble Ca and reduced electrolyte leakage in the fruit at harvest. After two months of cold storage followed by five days of shelf-life, the incidence and severity of bitter pit (BP) was lower on fruit from trees treated with ProCa PH, and higher on fruit from trees treated with GA4+7 PB. GA4+7 PB also increased the incidence of skin cracking and decay in the fruit. The results showed that ProCa application represents a feasible tool to reduce the incidence of BP. However, ProCa is more effective to reduce BP if applied weekly for five week before harvest.

Zooplankton Communities Associated With New and Regenerated Primary Production in the Atlantic Inflow North of Svalbard

The Arctic Ocean is changing rapidly with respect to ice cover extent and volume, growth season duration and biological production. Zooplankton are important components in the arctic marine food web, and tightly coupled to the strong seasonality in primary production. In this study, we investigate zooplankton composition, including microzooplankton, copepod nauplii, as well as small and large copepod taxa, and primary productivity in the dynamic Atlantic water inflow area north of Svalbard in May and August 2014. We focus on seasonal differences in the zooplankton community and in primary productivity regimes. More specifically, we examine how a shift from “new” (nitrate based) spring bloom to a “regenerated” (ammonium based) post bloom primary production is reflected in the diversity, life history adaptations and productivity of the dominant zooplankton. North of Svalbard, the seasonal differences in planktonic communities were significant. In spring, the large copepod Calanus finmarchicus dominated, but the estimated production and ingestion rates were low compared to the total primary production. In summer, the zooplankton community was composed by microzooplankton and the small copepod Oithona similis. The zooplankton production and ingestion rates were high in summer, and probably depended heavily on the regenerated primary production associated with the microbial loop. There was clear alteration from dominance of calanoid copepod nauplii in spring to Oithona spp. nauplii in summer, which indicates different reproductive strategies of the dominating large and small copepod species. Our study confirms the dependence and tight coupling between the new (spring bloom) primary production and reproductive adaptations of C. glacialis and C. hyperboreus. In contrast, C. finmarchicus appears able to take advantage of the regenerated summer primary production, which allows it to reach the overwintering stage within one growth season in this region north of Svalbard. This suggests that C. finmarchicus will be able to profit from the predicted increased primary production in the Arctic, a strategy also recognized in small copepod species such as O. similis. We speculate that the ability of the copepod species to utilize the regenerated summer primary production and microbial food web may determine the winners and losers in the future Arctic Ocean.

Food Web Functions and Interactions During Spring and Summer in the Arctic Water Inflow Region: Investigated Through Inverse Modeling

We used inverse modelling to reconstruct major planktonic food web carbon flows in the Atlantic Water inflow, east and north of Svalbard during spring (18-25 May) and summer (9-13 August), 2014. The model was based on three intensively sampled stations during both periods, corresponding to early, peak, and decline phases of a Phaeocystis and diatom dominated bloom (May), and flagellates dominated post bloom stages (August). The food web carbon flows were driven by primary production (290 to 2850 mg C m-2 d-1), which was channeled through a network of planktonic compartments, and ultimately respired (180 to 1200 mg C m2 d-1), settled out of the euphotic zone as organic particles (145 to 530 mg C m-2 d-1), or accumulated in the water column in various organic pools. The accumulation of dissolved organic carbon was intense (1070 mg C m-2 d-1) during the early bloom stage, slowed down during the bloom peak (400 mg C m-2 d-1), and remained low during the rest of the season. The heterotrophic bacteria responded swiftly to the massive release of new DOC by high, but decreasing carbon assimilation rates (from 534 to 330 mg C m-2 d-1) in May. The net bacterial production was low during the early and peak bloom (26 to 31 mg C m-2 d-1) but increased in the late and post bloom phases (> 50 mg C m-2 d-1). The heterotrophic nanoflagellates did not respond predictably to the different bloom phases, with relatively modest carbon uptake, 30 to 170 mg C m2 d-1. In contrast, microzooplankton increased food intake from 160 to 380 mg C m2 d-1 during the buildup and decline phases, and highly variable carbon intake 46 to 624 mg C m2 d-1, during post bloom phases. Mesozooplankton had an initially high, but decreasing carbon uptake in May (220 to 48 mg C m-2 d-1), followed by highly variable carbon consumption during the post bloom stages (40 to 190 mg C m-2 d-1). Zooplankton shifted from herbivory (92-97% of total food intake) during the early bloom phase to a herbivorous, detritovorous and carnivorous mixed diet as the season progressed.

Fruit size in different plum species (genus Prunus L.) is determined by post-bloom developmental processes and not by ovary characteristics at anthesis

The mechanisms driving drupe differentiation have been investigated in several plant species. Often, bigger fruits derive from bigger ovaries; however, in other species, ovary size is similar and differences in fruit size are determined by differences in post-bloom tissue development. The aim of this work was to investigate whether, in three Prunus species (P. salicina, P. domestica and P. cerasifera), fruit size is related to ovary size or whether it depends on post-bloom developmental processes. This study used microscope image analyses to evaluate ovary wall thickness at anthesis and fruit mesocarp thickness at final fruit size. In the same tissues (i.e. ovary wall and fruit mesocarp), we also measured cell area and number of cellular layers. Ovary wall thickness did not differ among the genotypes tested (except for Mirabolano, the smallest-fruited genotype, having slightly bigger ovaries) and was not correlated to either cell size or to the numbers of cell layers. Fruit mesocarp thickness varied three fold among genotypes and was strongly and positively correlated to the number of cell layers, and weakly and negatively correlated to cell size. No correlation was found between fruit weight (or mesocarp thickness or number of cell layers) and the respective ovary characteristic: bigger fruits did not derive from bigger ovaries. Fruit weight was instead related to the fruit-to-ovary weight and cell layer number ratios, indicating that fruit size in these species is related not to ovary characteristics, but to processes that occur to a different extent after bloom, particularly to a greater cell division. In particular, P. salicina cv. TC Sun, which had the biggest fruit, had a longer post bloom cell division activity and/or a higher post bloom cell division rate. Indeed, the number of TC Sun cell layers increased four times, while in the other species the mesocarp had twice the ovary layers. TC Sun also had the lowest increase in mesocarp cell area. This study represents a starting point to understand the mechanisms of cell division and expansion in Prunus species and their implication for fruit size management.

Hydrological Versus Biological Drivers of Nutrient and Carbon Dioxide Dynamics in a Coastal Lagoon

Coastal lagoons are dynamic aquatic systems that are susceptible to eutrophication due to long residence times and high inputs of nutrients. We hypothesise that groundwater-derived nutrients make a significant contribution to primary production, eutrophication and carbon cycling in these systems. Here, we report results from seasonal (pre-bloom, bloom and post bloom), nutrient, pCO2 and 222Rn (a natural groundwater tracer) surveys in a coastal lagoon that frequently experiences macroalgae blooms (Avoca Lagoon, Australia). Groundwater inputs of DIN and DIP deliver the nutrient load equivalent to the entire lagoon inventory in 1.6 to 3.5 days and 1.7 and 6 days respectively, indicating groundwater was a major source of inorganic nutrients to the system. Lagoon pCO2 displayed significant spatial and temporal variability, with the average pCO2 shifting from 1717 μatm during pre-bloom, to 137 μatm during the bloom and 3056 μatm post bloom. Radon-222 displayed a significant positive relationship with dissolved inorganic nitrogen (DIN) and pCO2 during the pre-bloom period. This suggests a hydrological dominance of surface water DIN and pCO2 during the pre-bloom period. During the bloom period, DIN displayed a positive relationship with pCO2 and negative relationship with dissolved oxygen, indicating a strong biological control over the nutrient pool. Phosphate did not appear to be controlled by either groundwater inputs, or ecosystem metabolism throughout the study. While groundwater discharge stimulated primary production through nutrient inputs (thus reducing surface water CO2), it also directly delivered significant quantities of CO2 to surface waters. The net effect of groundwater inputs of nutrients and dissolved carbon into the lagoon was a stimulation of CO2 fluxes to the atmosphere.

Influence of harvesting stage on herb, essential oil and artemisinin yields in the antimalarial herb, Artemisia annua L.

The investigation was carried out to standardize the harvesting stage for maximum oil and essential oil yield in Artemisia annua L. in the semi arid region of Gujarat. The experiment was laid out in randomized block design with seedlings planted at the age of six weeks and harvested at five different phonological stages.viz., early vegetative (March), late vegetative (May), pre bloom (September), bloom (October) and post bloom (November) stages. The results revealed that the maximum herb could be obtained in the late vegetative stage (31.74 t/ha) followed by bloom stage (30.19 t/ha). The leaf yield was maximum in the bloom stage (6.39t/ha). The essential oil content and yield was maximum in the bloom stage (0.61% and 61.30 kg/ha, respectively) followed by post bloom stage (0.55% and 38.87 kg/ha) and minimum in early vegetative stage (0.18% and 8.29 kg/ha). However, the artemisinin content was maximum in the late vegetative stage (0.48%) followed by prebloom stage (0.44%). Similarly, the artemisinin yield per hectare was maximum in the crop harvested during late vegetative stage followed by the prebloom stage. The essential oil obtained during different harvest stages were subjected to GC-MS analysis in which, the main compounds were camphor (28.6–31.7%), 1, 8cineole (2.1–20.8%), germacrene D (3.8–12.0%), β-caryophyllene (2.8–6.9%), trans-β-farnesene (0.7–4.5%), α-pinene (0.5–2.4%), p-cymene (2.1–2.3%) and terpinen-4-ol (0.9–2.1%). Camphor was found to be a major compound in the oil at all growth stages.

An approach for the identification of exemplar sites for scaling up targeted field observations of benthic biogeochemistry in heterogeneous environments

Continental shelf sediments are globally important for biogeochemical activity. Quantification of shelf-scale stocks and fluxes of carbon and nutrients requires the extrapolation of observations made at limited points in space and time. The procedure for selecting exemplar sites to form the basis of this up-scaling is discussed in relation to a UK-funded research programme investigating biogeochemistry in shelf seas. A three-step selection process is proposed in which (1) a target area representative of UK shelf sediment heterogeneity is selected, (2) the target area is assessed for spatial heterogeneity in sediment and habitat type, bed and water column structure and hydrodynamic forcing, and (3) study sites are selected within this target area encompassing the range of spatial heterogeneity required to address key scientific questions regarding shelf scale biogeochemistry, and minimise confounding variables. This led to the selection of four sites within the Celtic Sea that are significantly different in terms of their sediment, bed structure, and macrofaunal, meiofaunal and microbial community structures and diversity, but have minimal variations in water depth, tidal and wave magnitudes and directions, temperature and salinity. They form the basis of a research cruise programme of observation, sampling and experimentation encompassing the spring bloom cycle. Typical variation in key biogeochemical, sediment, biological and hydrodynamic parameters over a pre to post bloom period are presented, with a discussion of anthropogenic influences in the region. This methodology ensures the best likelihood of site-specific work being useful for up-scaling activities, increasing our understanding of benthic biogeochemistry at the UK-shelf scale.

Effects of brassinosteroid (24-epibrassinolide) on yield and quality of grape ("Vitis vinifera" L.) 'Thompson Seedless'

Berry growth ripening process and yield are directly related with nutrition status and phytohormones during fruit growth and development stages. Brassinosteroid (24-epibrassinolide) is one of the plant growth substances that influence different physiological processes including fruit growth and development. In this study, the effect of brassinosteroid (Br) application on the yield and berry quality of 'Thompson Seedless' was investigated in a commercial vineyard, Malayer, Hamedan, Iran. Br solution concentrations of 0, 0.2, 0.4, 0.6 mg·L-1 at five stages (budbreak (S1), prebloom (S2), middle of bloom (S3), post bloom (S4) and veraison (S5) were sprayed. The results showed that the Br application has significant positive effects on bunch morphology and berry quantity and quality. Among levels of Br, the highest yields were related to the application of Br at the rate of 0.6 mg·L-1 in the post bloom and veraison stages, and the lowest was found in the bud break stage. Spraying Br in the post bloom and veraison stages had the greatest effect on berry quality. Also, the highest content of total phenol and antioxidant capacity were obtained with 0.6 mg·L-1 of Br application at veraison stage. In this study, we provided evidence to show that using steroidal plant hormones (Br) may play an essential role in improving the yield and quality of 'Thompson Seedless'.

Upward nitrate flux and downward particulate organic carbon flux under contrasting situations of stratification and turbulent mixing in an Arctic shelf sea

Increased sea ice melt alters vertical surface-mixing processes in Arctic seas. More melt water strengthens the stratification, but an absent ice cover also exposes the uppermost part of the water column to wind-induced mixing processes. We conducted a field study in the Barents Sea, an Arctic shelf sea, to examine the effects of stratification and vertical mixing processes on 1) the upward nitrate flux (into surface layers <65 m) and 2) the downward flux of particulate organic carbon (POC) to ≤200 m. In the Arctic-influenced, drift ice-covered northern Barents Sea, we found a low upward nitrate flux into the surface layers (<0.1 mmol nitrate m–2 d–1) and a moderate downward POC flux (40–200 m: 150–250 mg POC m–2 d–1) during the late phase of a peak bloom. A 1-D residence time calculation indicated that the nitrate concentration in the surface layers constantly declined. In the Atlantic-influenced, ice-free, and weakly stratified southern Barents Sea a high upward nitrate flux was found (into the surface layers ≤25 m: >5 mmol nitrate m–2 d–1) during a post bloom situation which was associated with a high downward POC flux (40–120 m: 260–600 mg POC m–2 d–1). We suggest that strong wind events during our field study induced vertical mixing processes and triggered upwards nitrate flux, while a combination of down-mixed phytoplankton and fast-sinking mesozooplankton fecal pellets enhanced the downward POC flux. The results of this study underscore the need to further investigate the role of strong, episodic wind events on the upward nitrate and downward POC fluxes in weakly stratified regions of the Arctic that may be ice-free in future.

Atlantic Advection Driven Changes in Glacial Meltwater: Effects on Phytoplankton Chlorophyll-a and Taxonomic Composition in Kongsfjorden, Spitsbergen

Phytoplankton biomass and composition was investigated in a high Arctic fjord (Kongsfjorden, 79˚N, 11˚40’E) using year round weekly pigment samples collected from October 2013 to December 2014. In addition, phytoplankton dynamics supplemented with physical and chemical characteristics of the 2014 spring bloom (April –June 2014) were assessed in two locations in Kongsfjorden. The goal was to elucidate effects of Atlantic advection on spatial phytoplankton chlorophyll-a (chl-a) and taxonomic composition. Chl-a declined during the polar night to a minimum of 0.01 mg m-3, followed by a 1000-fold increase until May 28. Atlantic advection prevented sea ice formation and increased springtime melting of marine terminating glaciers. This coincided with spatial and temporal differences in abundances of flagellates (prasinophytes, haptophytes, cryptophytes, and chrysophytes) and diatoms in early spring. More flagellated phytoplankton were observed in the non-stratified central Kongsfjorden, whereas diatoms were more abundant in the stratified inner fjord. Contrasting conditions between locations were reduced when glacial melt water stratification expanded towards the mouth of the fjord, mediating a diatom dominated surface bloom at both locations. We suggest that glacial melt water governs spring bloom spatial timing and composition in the absence of sea ice driven stratification. The spring bloom exhausted surface nutrient concentrations by the end of May. The nutrient limited post bloom period (June-October) was characterized by reduced biomass and pigments of flagellated phytoplankton, consisting of prasinophytes, haptophytes, chrysophytes and to a lesser extent cryptophytes and peridinin-containing dinoflagellates.

Agro-metrological investigation of bumper apple productivity in Himachal Pradesh, India

The study aimed to investigate the productivity and weather relationship for the apple growing areas of Himachal Pradesh viz., Kalpa, Bhuntar and Shimla in district Kinnaur, Kullu and Shimla, respectively. The results revealed that pre bloom period (November to February) in the year 2009-10 remained cooler. The minimum temperature of 0.4 to 0.9, 1.0 to 1.1°C and 1.9 to 2.2°C and maximum temperature of 6.7, 1.0 to 1.1 and 1.7°C were lower in Shimla, Bhuntar and Kalpa region, respectively compared to 1995-2009.. The maximum temperature for the chill accumulation months of November, December, January and February during 2009-10 showed 13 to 19 per cent lower compared to 1995-2009. The average pre bloom rainfall during 2010 was 39 to 57 per cent higher than 1995-2009 indicating sustainable bloom period. The 3 to 4°C temperature rise during March 2010 (19 to 24°C) as compared to 1995-2009 (16 to 21.4°C) coupled with 52 per cent higher precipitation benefited the crop in profuse flowering and hence good fruit set. The average maximum temperature during the post bloom period (May-June) in 2009-10 was 1°C higher compared to the previous years coupled with 23 per cent higher rainfall resulting in an highest productivity. The highest productivity (8.57 MT/ha) during 2010 which was 58 per cent higher than the previous years can be ascribed due to the favorable low temperature in pre bloom period and increase in the temperature inthe month of March along with adequate rainfall in the bloom and post bloom period.

METAMITRON REPLACING CARBARYL IN POST BLOOM THINNING OF APPLE TREES

ABSTRACT Carbaryl or the mixture of carbaryl with NAA (naphthalene acetic acid) or BA (benzyladenine) are the post-bloom chemical thinners most widely used in apple thinning in Brazil. The marketing restriction of carbaryl demands new options of apple post-bloom thinners, requiring the evaluation of others compounds for this purpose. Metamitron is one of the substances that may be used in chemical thinning of apples. Metamitron was evaluated at two concentrations, alone or in mixture with BA, in ‘MaxiGala’, ‘Fuji Suprema’ and ‘Fred Hough’ apple cultivars. Applications of metamitron at 384 mg L-1 and at 768 mg L-1 in a mixture with BA, ranging from 40 mg L-1 to 80 mg L-1, sprayed on fruits with diameter ranging from 5 to 25 mm were compared with the standard treatment and hand thinning. The experimental design was a randomized complete block with 4-6 repetitions of a single plant. The variables analyzed were: fruit set (%); percentage of floral clusters with 1, 2, 3, 4 or more fruits; fruit yield (kg); average fruit fresh mass (g) and percentage of dropped fruit after thinning. Metamitron alone or in combination with BA reduced production per plant and significantly increased the fresh weight of fruits in all cultivars tested. Metamitron at 800 mg L-1 resulted in excessive fruit thinning, especially in ‘MaxiGala’ cultivar. Metamitron or metamitron + BA have potential to compose the program of chemical thinning of apple trees to replace carbaryl.

Bloom of micro alga Chlorella marina (Butcher) in the Karapad lagoon, Gulf of Mannar, southeast coast of India

A study was conducted to find out the possible cause of sudden changes in the colour of the Karapad lagoon water and associated variation in the hydrography. The discolouration of lagoon water was noticed after the excavation work to deepen the lagoon area by the Municipal authorities to enable free boating. Microscopic examination of the lagoon water revealed the blooming of micro alga Chlorella marina. The blooming lasted for a month and has not caused any adverse effect. During the bloom days, the algal cell density attained a peak of 3.1x 105 cells l-1 on 5th day. Very high chlorophyll concentration was noticed in the lagoon water during the bloom days than the post bloom days. The studies revealed that the nutrient enrichment due to the re-suspension of sediments from the excavation activities might have triggered the algal outburst in the Karapad lagoon. Along with high nutrients, the surface water temperature and salinity might also have supported the algal proliferation.

The Influence of Thinning Agent on base of 6-BA and NAA on Productivity and Fruit Quality of „Gala Must” Variety

Chemical thinning of pome fruits is important measure for the profitable agricultural production of fruits. Chemical thinning provides a good yield potential for the following vegetation. Thinning the apple crop during the post bloom period is absolutely essential to ensure large fruit size, superior fruit quality, and reliable annual cropping. To evaluate the influence of thinning agent on base of 6-benzyladenine (6-BA) and naphthalene acetic acid (NAA) in reducing fruit set and quality in Gala Must apple trees. The experimental plot was founded in 2006 with trees of „knip boom” canopy type. The study subject of the experience was Gala Must apple variety grafted on M 9. The trees were trained as slender spindles. The distance of plantation is 3.5 x 1.2 m. The tested combination was 6-BA and NAA. The preparation was sprayed on the trees either one time, when the king fruit diameter was 10-15 mm. The research was conducted during the period of 2011 year. During the research, it was studied the number of blossom clusters before thinning degree, fruit at harvest time, yield, mean fruit weight, average fruit diameter, size classes based on their diameter and the number of pygmy fruits. It was established that, the good effect of thinning was noticed after single application of 100 ppm 6-BA + NAA 10 ppm. The combined treatment with 6-BA 100 ppm + NAA 10 ppm has a significant effect on yield, mean fruit weight and positively influenced fruit size, the distribution of apples in size classes.

Uptake and elimination of brevetoxin in the invasive green mussel, Perna viridis, during natural Karenia brevis blooms in southwest Florida.

Perna viridis is a recently introduced species to US coastal waters and have vigorously spread throughout the southeastern seaboard since their invasion. Little information regarding their response to local environmental factors has been reported including responses to the local HAB species, Karenia brevis. This study monitored the tissue toxin concentration of brevetoxins in P.viridis from existing populations throughout two consecutive natural K.brevis blooms. The results showed P.viridis to rapidly accumulate PbTx upon exposure to the bloom, far exceeding the peak tissue concentrations of oysters, Crassostrea virginica, sampled during the same period, 57,653±15,937 and 33,462±10,391ngg(-1) PbTx-3 equivalent, respectively. Further, P.viridis retained high PbTx concentrations in their tissues post bloom remaining above the regulatory limit for human consumption for 4-5 months, significantly longer than the depuration time of 2-8 weeks for native oyster and clam species. In the second year, the bloom persisted at high cell concentrations resulting in prolonged exposure and higher PbTx tissue concentrations indicating increased bioaccumulation in green mussels. While this species is not currently harvested for human consumption, the threat for post bloom trophic transfer could pose negative impacts on other important fisheries and higher food web implications.