Distribution of nutrients in the root zone affects yield, quality and blossom end rot of tomato fruits

Tomato plants (Lycopersicon esculentum Mill. 'DRK') were grown hydroponically in two experiments to determine the effects of nutrient concentration and distribution in the root zone on yield, quality and blossom end rot (BER). The plants were grown in rockwool with their root systems divided into two portions. Each portion was irrigated with nutrient solutions with either the same or different electrical conductivity (EC) in the range 0 to 6 dS m(-1). In both experiments, fruit yields decreased as EC increased from moderate to high when solutions of equal concentration were applied to both portions of the root system. However, higher yields were obtained when a solution with high EC was applied to one portion of the root system and a solution of low EC to the other portion. For example, the fresh weight of mature fruits in the 6/6 treatment was only 20% that of the 3/3 treatment but the 6/0 treatment had a yield that was 40% higher. The reduction in yield in the high EC treatments was due to an increase in the number of fruits with BER and smaller fruit size. BER increased from 12% to 88% of total fruits as EC increased from 6/0 to 6/6 and fruit length decreased from 67 mm to 52 mm. Fruit quality (expressed as titratable acidity and soluble solids) increased as EC increased. In summary, high yields of high quality tomatoes with minimal incidence of BER were obtained when one portion of the root system was supplied with a solution of high EC and the other portion with a solution of moderate or zero EC.

Uneven distribution of nutrients in the root zone affects the incidence of blossom end rot and concentration of calcium and potassium in fruits of tomato

Tomato plants ( Lycopersicon esculentum Mill. var. DRK) were grown hydroponically to determine the effect of an uneven distribution of nutrients in the root zone on blossomend rot (BER) and Ca and K concentrations in the fruits. The plants were grown in rockwool with their root system divided into two portions. Each portion was irrigated with nutrient solutions with either the same or the different electrical conductivity (EC) in the range 0 to 6 dS m(-1). Solutions with high EC supplied to both sides of the root system significantly increased the incidence of BER. However, when only water or a solution of low EC was supplied to one portion, BER was reduced by 80%. Fruit yields were significantly higher ( P < 0.01) for plants that received solutions of the uneven EC treatments (6/0 or 4.5/0 EC treatment). Plants supplied with solutions of uneven EC generally had higher leaf and fruit concentrations of Ca but lower concentrations of K than those supplied with solutions of high EC. There was no difference in Ca concentration at the distal end of young fruits of the uneven EC treatment but it was reduced in the high EC treatments. The concentration of K in the mature fruits of the uneven EC treatments was lower than that of the high EC treatments and higher or similar that of the 3/3 or 2.5/2.5 EC treatments ( controls). A clear relationship was found between the incidence of BER and the exudation rate. High rate of xylem exudation was observed in the uneven EC treatments. Reduction of BER in the uneven EC treatments is most likely to be the effect of high exudation rate on Ca status in the young fruits. It was concluded that high EC of solution had positive effects on Ca concentration and incidence of BER provided that nutrient solution with low EC or water is supplied to the one portion of the root system.

Movements, activity patterns and home range of a female brown bear (Ursus arctos, L.) in the Rodopi Mountain Range, Greece

Movements and activity patterns of an adult radio-tagged female brown bear accompanied by her cubs were documented for the first time in Rodopi area (NE Greece) from August 2000 to July 2002. Average daily movements were 2.45 +/- 2.26 SD km, (range 0.15-8.5 km). The longest daily range could be related to human disturbance (hunting activity). The longest seasonal distance (211 km), during Summer 2001 coincided with the dissolution of the family. With cubs, the female was more active during daytime (73 % of all radio-readings) than when solitary (28 %). The female switched to a more crepuscular behaviour, after separation from the yearling (July 2001). According to pooled data from 924 activity - recording sessions, during the whole monitoring period, the female was almost twice as active during day time while rearing cubs (51 % active) than when solitary (23 %). The autumn and early winter home range size of the family was larger (280 km(2)) than after the separation from the cubs (59 km(2)). During the family group phase, home range size varied from 258 km(2) in autumn to 40 km(2) in winter (average denning period lasted 107 days : December 2000-March 2001). The bear hibernated in the Bulgarian part of the Rodopi Range during winters of 2001 and 2002.

The effect of carrier substrate, dose rate and time of application on biocontrol efficacy of fungal antagonists against Armillaria root rot of strawberry plants.

In a glasshouse experiment using potted strawberry plants (cv. Cambridge Favourite) as hosts, the effect of selected fungal antagonists grown on 25 or 50 g of mushroom compost containing autoclaved mycelia of Agaricus bisporus, or wheat bran was evaluated against Armillaria mellea. Another glasshouse experiment tested the effect of application time of the antagonists in relation to inoculations with the pathogen. A significant interaction was found between the antagonists, substrates and dose rates. All the plants treated with Chaetomium olivaceum isolate Co on 50 g wheat bran survived until the end of the experiment which lasted 482 days, while none of them survived when this antagonist was added to the roots of the plants on 25 g wheat bran or 25 or 50 g mushroom compost. Dactylium dendroides isolate SP had a similar effect, although with a lower host survival rate of 33.3%. Trichoderma hamatum isolate Tham 1 and T. harzianum isolate Th23 protected 33.3% of the plants when added on 50 g and none when added on 25 g of either substrate, while 66.7% of the plants treated with T. harzianum isolate Th2 on 25 g, or T viride isolate TO on 50 g wheat bran, survived. Application of the antagonists on mushroom compost initially resulted in development of more leaves and healthier plants, but this effect was not sustained. Eventually, plants treated with the antagonists on wheat bran had significantly more leaves and higher health scores. The plants treated with isolate Th2 and inoculated with Armillaria at the same time had a survival rate of 66.7% for the duration of the experiment (475 days), while none of them survived that long when the antagonist and pathogen were applied with an interval of 85 days in either sequence. C. olivaceum isolate Co showed a protective effect only, as 66.7% of the plants survived when they were treated with the antagonist 85 days before inoculation with the pathogen, while none of them survived when the antagonist and pathogen were applied together or the infection preceded protection.

Cultural techniques for improvement in biocontrol potential of fungal antagonists for biological control of Armillaria root rot of strawberry plants under glasshouse conditions

Several in vitro and in vivo experiments were conducted to develop an effective technique for culturing potential fungal antagonists (isolates of Trichoderma harzianum, Dactylium dendroides, Chaetomium olivaceum and one unidentified fungus) selected for activity against Armillaria mellea. The antagonists were inoculated onto (1) live spawn of the oyster mu shroom (Pleurotus ostreatus), (2) extra-moistened or sucrose-enriched mushroom composts containing living or autoclaved mycelia of P. ostreatus or Agaricus bisporus (button mushroom), (3) pasteurized compost with or without A. bisporus mycelium, wheat bran, wheat germ and (4) spent mushroom composts with living mycelia of A. bisporus, P. ostreatus or Lentinus edodes (the Shiitake mushroom). In one experiment, a representative antagonist (isolate Th2 of T. harzianum) was grown together with the A. bisporus mycelium, while in another one, the antagonist was first grown on wheat germ or wheat bran and then on mushroom compost with living mycelium of A. bisporus. Some of the carrier substrates were then added to the roots of potted strawberry plants in the glasshouse to evaluate their effectiveness against the disease. The antagonists failed to grow on the spawn of P. ostreatus even after reinoculations and prolonged incubation. Providing extra moisture or sucrose enrichment also did not improve the growth of Th2 on mushroom composts in the presence of living mycelia of A. bisporus or P. ostreatus. The antagonist, however, grew rapidly and extensively on mushroom compost with autoclaved mycelia, and also on wheat germ and wheat bran. Colonization of the substrates by the antagonist was positively correlated with its effectiveness in the glasshouse studies. Whereas only 33.3% of the inoculated control plants survived in one experiment monitored for 560 days, 100% survival was achieved when Th2 was applied on wheat germ or wheat bran. Growth of the antagonist alone on pasteurized or sterilized compost (without A. bisporus mycelia) and simultaneous growth of the antagonist and mushroom on pasteurized compost did not improve survival over the inoculated controls, but growth over mushroom compost with the living mycelium resulted in 50% survival rate. C. olivaceum isolate Co was the most effective, resulting in overall survival rate of 83.3% compared with only 8.3% for the inoculated and 100% for the uninoculated (healthy) controls. This antagonist gave the highest survival rate of 100% on spent mushroom compost with L. edodes. T harzianum isolate Th23, with 75% survival rate, was the most effective on spent mushroom compost with P. ostreatus, while D. dendroides isolate SP resulted in equal survival rates of 50% on all the three mushroom composts.

Effects of straw and silicon soil amendments on some foliar and stem-base diseases in pot-grown winter wheat

Four foliar and two stem-base pathogens were inoculated onto wheat plants grown in different substrates in pot experiments. Soils from four different UK locations were each treated in three ways: (i) straw incorporated in the field at 10 t ha−1 several months previously; (ii) silicon fertilization at 100 mg L−1 during the experiment; and (iii) no amendments. A sand and vermiculite mix was used with and without silicon amendment. The silicon treatment increased plant silica concentrations in all experiments, but incorporating straw was not associated with raised plant silica concentrations. Blumeria graminis and Puccinia recondita were inoculated by shaking infected plants over the test plants, followed by suitable humid periods. The silicon treatment reduced powdery mildew (B. graminis) substantially in sand and vermiculite and in two of the soils, but there were no effects on the slight infection by brown rust (P. recondita). Phaeosphaeria nodorum and Mycosphaerella graminicola were inoculated as conidial suspensions. Leaf spot caused by P. nodorum was reduced in silicon-amended sand and vermiculite; soil was not tested. Symptoms of septoria leaf blotch caused by M. graminicola were reduced by silicon amendment in a severely infected sand and vermiculite experiment but not in soil or a slightly infected sand and vermiculite experiment. Oculimacula yallundae (eyespot) and Fusarium culmorum (brown foot rot) were inoculated as agar plugs on the stem base. Severity of O. yallundae was reduced by silicon amendment of two of the soils but not sand and vermiculite; brown foot rot symptoms caused by F. culmorum were unaffected by silicon amendment. The straw treatment reduced severity of powdery mildew but did not detectably affect the other pathogens. Both straw and silicon treatments appeared to increase plant resistance to all diseases only under high disease pressure.

Distribution of nutrients in the root zone affects yield, quality and blossom end rot of tomato fruits

Tomato plants (Lycopersicon esculentum Mill. 'DRK') were grown hydroponically in two experiments to determine the effects of nutrient concentration and distribution in the root zone on yield, quality and blossom end rot (BER). The plants were grown in rockwool with their root systems divided into two portions. Each portion was irrigated with nutrient solutions with either the same or different electrical conductivity (EC) in the range 0 to 6 dS m(-1). In both experiments, fruit yields decreased as EC increased from moderate to high when solutions of equal concentration were applied to both portions of the root system. However, higher yields were obtained when a solution with high EC was applied to one portion of the root system and a solution of low EC to the other portion. For example, the fresh weight of mature fruits in the 6/6 treatment was only 20% that of the 3/3 treatment but the 6/0 treatment had a yield that was 40% higher. The reduction in yield in the high EC treatments was due to an increase in the number of fruits with BER and smaller fruit size. BER increased from 12% to 88% of total fruits as EC increased from 6/0 to 6/6 and fruit length decreased from 67 mm to 52 mm. Fruit quality (expressed as titratable acidity and soluble solids) increased as EC increased. In summary, high yields of high quality tomatoes with minimal incidence of BER were obtained when one portion of the root system was supplied with a solution of high EC and the other portion with a solution of moderate or zero EC.

Uneven distribution of nutrients in the root zone affects the incidence of blossom end rot and concentration of calcium and potassium in fruits of tomato

Tomato plants ( Lycopersicon esculentum Mill. var. DRK) were grown hydroponically to determine the effect of an uneven distribution of nutrients in the root zone on blossomend rot (BER) and Ca and K concentrations in the fruits. The plants were grown in rockwool with their root system divided into two portions. Each portion was irrigated with nutrient solutions with either the same or the different electrical conductivity (EC) in the range 0 to 6 dS m(-1). Solutions with high EC supplied to both sides of the root system significantly increased the incidence of BER. However, when only water or a solution of low EC was supplied to one portion, BER was reduced by 80%. Fruit yields were significantly higher ( P < 0.01) for plants that received solutions of the uneven EC treatments (6/0 or 4.5/0 EC treatment). Plants supplied with solutions of uneven EC generally had higher leaf and fruit concentrations of Ca but lower concentrations of K than those supplied with solutions of high EC. There was no difference in Ca concentration at the distal end of young fruits of the uneven EC treatment but it was reduced in the high EC treatments. The concentration of K in the mature fruits of the uneven EC treatments was lower than that of the high EC treatments and higher or similar that of the 3/3 or 2.5/2.5 EC treatments ( controls). A clear relationship was found between the incidence of BER and the exudation rate. High rate of xylem exudation was observed in the uneven EC treatments. Reduction of BER in the uneven EC treatments is most likely to be the effect of high exudation rate on Ca status in the young fruits. It was concluded that high EC of solution had positive effects on Ca concentration and incidence of BER provided that nutrient solution with low EC or water is supplied to the one portion of the root system.

Managing Armillaria root rot

Controlling Armillaria infections by physical and chemical methods alone is at present inadequate, ineffective, or impractical. Effective biological control either alone or in integration with another control strategy appears necessary. Biological control agents of Armillaria function by the antagonists inhibiting or preventing its rhizomorphic and mycelial development, by limiting it to substrate already occupied, by actively pre-empting the substrate, or by eliminating the pathogen from substrate it has already occupied. Among the most thoroughly investigated antagonists of Armillaria are Trichoderma species. Depending on the particular isolate of a Trichoderma species, control may be achieved by competition, production of antibiotics, or by mycoparasitism. The level of control is also influenced by the growth and carrier substrate of the antagonist, time of application in relation to the occurrence of the disease, and several environmental conditions. Among a range of the other antagonists are several cord-forming fungi and an isolate of Dactylium dendroides. Integrating biological methods with an appropriate method of chemical could control the disease more effectively. However it is essential to determine whether the antagonist or the fungicide should be applied first, and the time interval between.

Regional variation in the microhardness and mineralization of vertebrae from brown and rainbow trout

Regional variation in properties of vertebral bone from brown Salmo trutta and rainbow trout Oncorhychus mykiss were explored by using microhardness tests. Statistically-significant positive correlations were identified between the microhardness of bone and its mineral content. In both brown and rainbow trout, the vertebrae from the caudal region were harder than those of the trunk region. There was a significant difference between the species; microhardness of bone from vertebrae of rainbow trout was greater than those from brown trout.

Thermogenic and metabolic consequences of thyroid hormone treatment in brown and white adipose tissue

Male rats were treated with triiodothyronine in the drinking water for 12 days. In vitro rates of isoprenaline stimulated lipolysis were significantly greater in brown but not white adipose tissue. Rates of [14C]glucose incorporation into triacylglycerols were significantly reduced in BAT (brown adipose tissue) and WAT (white adipose tissue) under basal and isoprenaline stimulated conditions. In a second experiment, hyperthyroid animals showed impaired weight gain, despite increased food intake during 19 days' treatment. Energy expenditure on days 5 and 12, and BAT core temperature differences (TBAT - TCORE) on day 19, were significantly greater than in control animals. Epididymal white fat pad weight was reduced and interscapular brown fat pad weight increased by triiodothyronine treatment.