Nutrient limitations to bacterial and fungal growth during cellulose decomposition in tropical forest soils

Nutrients constrain the soil carbon cycle in tropical forests, but we lack knowledge on how these constraints vary within the soil microbial community. Here, we used in situ fertilization in a montane tropical forest and in two lowland tropical forests on contrasting soil types to test the principal hypothesis that there are different nutrient constraints to different groups of microorganisms during the decomposition of cellulose. We also tested the hypotheses that decomposers shift from nitrogen to phosphorus constraints from montane to lowland forests, respectively, and are further constrained by potassium and sodium deficiency in the western Amazon. Cellulose and nutrients (nitrogen, phosphorus, potassium, sodium, and combined) were added to soils in situ, and microbial growth on cellulose (phospholipid fatty acids and ergosterol) and respiration were measured. Microbial growth on cellulose after single nutrient additions was highest following nitrogen addition for fungi, suggesting nitrogen as the primary limiting nutrient for cellulose decomposition. This was observed at all sites, with no clear shift in nutrient constraints to decomposition between lowland and montane sites. We also observed positive respiration and fungal growth responses to sodium and potassium addition at one of the lowland sites. However, when phosphorus was added, and especially when added in combination with other nutrients, bacterial growth was highest, suggesting that bacteria out-compete fungi for nitrogen where phosphorus is abundant. In summary, nitrogen constrains fungal growth and cellulose decomposition in both lowland and montane tropical forest soils, but additional nutrients may also be of critical importance in determining the balance between fungal and bacterial decomposition of cellulose.     

Screening potato varieties for short dormancy

Summary Autumn grown potatoes harvested in December cannot be used for planting in February–March, as they are still dormant at that time. The lengthy dormant period ofUp-to-Date, the main variety cultivated in Israel, was found to be the bottleneck of the problem of supply of locally grown seed tubers. In order to find varieties with a shorter dormant period, 52 varieties from different sources were introduced. The seed material was propagated twice before it was used for the first screening test in spring 1956. The first test has shown that varieties with a short dormant period gave the best results and those with a long one the worst. The second screening in spring 1957, in which a limited number of the most promising varieties were tested, has shown that length of growing period is at least as important as length of dormant period, and that early and medium-early varieties are best. In spite of the results obtained we consider that it will be necessary to breed new varieties more adapted to the specific requirements of growing two crops a year.

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Zusammenfassung Im Herbst ausgepflanzte und im Dezember geerntete Kartoffeln k?nnen nicht zum Auspflanzen im Februar verwendet werden, da sie sich dann noch in der Keimruhe befinden. Die ziemlich lange Keimruhe vonUp-to-Date, der in Israel am meisten angebauten Sorte, erwies sich als die gr?sste Schwierigkeit bei der L?sung des Problems der Versorgung mit einheimischem Saatgut. Um Sorten mit kürzerer Keimruhe zu finden, wurden 52 Sorten verschiedener Herkunft eingeführt. Das Saatgut wurde zweimal fortgezüchtet, bevor es für den ersten Auslesetest im Frühjahr 1956 verwendet wurde. Der erste Versuch zeigte, dass Sorten mit kurzer Keimruhe die besten und Sorten mit langer Keimruhe die schlechtesten Resultate ergaben. Die zweite Auslese im Frühjahr 1957, wobei eine kleinere Anzahl der aussichtsreichsten Sorten geprüft wurde, zeigte, dass die Dauer der Wachstumsperiode mindestens ebenso wichtig ist wie die L?nge der Keimruhe und dass frühe und mittelfrühe Sorten die besten sind. Ungeachtet dieser Ergebnisse halten wir es für angezeigt, neue Sorten zu züchten, die den besonderen Ansprüchen einer zweimaligen Ernte im Jahr besser genügen.

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Résumé Les pommes de terre d'automne récoltées en décembre ne peuvent servir de semence en févriermars, puisqu'elles se trouvent encore à l'état latent à cette époque. La période de latence assez prolongée de l'Up-to-date, la principale variété cultivée en Israel, constitue le majeur obstacle à l'approvisionnement en semences locales. Afin de trouver des variétés à courte période de latence, nous avons introduit 52 variétés de différentes provenances. Celles-ci ont d? être multipliées deux fois avant que nous ayons pu entreprendre le premier essai au printemps 1956. Ce premier essai a permis de constater que les variétés à courte période de latence étaient les meilleures, celles à période de latence prolongée donnant les résultats les moins bons. La seconde sélection fut effectuée au printemps 1957. A cette occasion, un plus petit nombre de variétés particulièrement prometteuses furent étudiées. Il fut constaté que la durée de végétation a une importance au moins égale à celle de la durée de latence. Les variétés précoces et moyennes étaient les meilleures. Malgré les résultats de cette étude, nous en sommes arrivés à cette conclusion qu'il nous faudra sélectionner, des variétés nouvelles, mieux adaptées aux exigences particulières de la culture de la pomme de terre effectuée à deux reprises dans la même année.

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Publication of the National and University Institute of Agriculture, Rehovot, 1960. Series No. 354-E.     

Effects of temperature,relative humidity and age of conidia on the incidence of spotting on gerbera flowers caused by Botrytis cinerea

In recent years, spotting of ray florets of gerbera flowers has become an important problem. This type of small necrotic lesions may occur before, but especially shortly after harvesting the flowers.Botrytis cinerea was easily isolated from such lesions. Inoculation withB. cinerea only gave typical necrotic lesions, when dry conidia were dusted on the flowers with a short period of high rh after inoculation. At 18–25 °C a high rh for at least 5 hours was necessary. Rotting of ray florets and receptacles byB. cinerea occurred when inoculated flowers were kept wet for a few days. Spots consist of one to several necrotic, usually epidermal cells. A single conidium could give rise to a necrotic lesion after germination. Germination of conidia and lesion formation occurred between 4 and 25 °C; at 30 °C, germination and lesion formation did not occur. Between 18 and 25 °C, many lesions became visible within 1 day after inoculation; at 4 °C it took 2 to 3 days before lesions could be seen. If kept dry, conidia ofB. cinerea remained ungerminated on ray florets of gerbera flowers and could be removed from the ray florets. Within 1 day at high rh, germination occurred and lesions were produced. Conidia ofB. cinerea, stored dry, were able to survive much longer than the lifetime of a gerbera flower. Even after storage at room temperature for up to 14 months, some conidia were able to germinate in vitro and on ray florets and induce the formation of lesions. Addition of gerbera pollen diffusate stimulated germination and lesion formation.     

Field attraction of Cerambyx welensii to fermentation odors and host monoterpenes

Cerambyx welensii Küster is one of the greatest threats to Quercus suber L. and Quercus ilex L. in Spain. Efficient control methods for this species are currently being tested, and the use of traps baited with food-related products for their monitoring and control has been proposed. Cerambyx welensii adults prefer to colonize old or decayed trees, in which cortical exudates frequently release fermentation odors. Fermentation-related compounds, such as ethanol, have been cited as attractants to various hardwood woodborers (as Cerambyx cerdo L.), used either alone or sometimes in combination with other host odors. In this work, we conducted field experiments to ascertain whether chemical blends mimicking fermentation odors were attractive for C. welensii. To this end, we used three types of traps (multiple funnel, cross-vane and single-funnel) baited with six synthetic blends including one or more fermentation-related chemicals (ethanol, ethyl acetate, 3-methyl-1-butanol, acetaldehyde, 2-methyl-1-propanol and 2-methyl-1-butanol), various food-related products (beer, melon and red wine mixed with peach juice) and host monoterpenes (α-pinene, β-pinene, limonene, α-phellandrene and camphene). At high release rates (5–11 g/day), various synthetic blends proved attractive irrespective of trap type. Our results contribute to understand the impact of volatile organic compounds in host selection by woodborers infesting deciduous trees. The results hold promise for optimizing trapping strategies to control C. welensii within an integrated pest management framework.     

Effect of red grapes co-winemaking in polyphenols and color of wines

The red grapes co-winemaking effect on phenolic fraction and wine color has been studied for the first time, where Monastrell was comacerated and cofermentated with Cabernet Sauvignon and Merlot. Changes in the relative abundance of anthocyanins were observed as well as hyperchromic shifts at 530 and 620 nm; these effects remain constant after aging. Co-winemaking also favored copigmentation, giving way to more stable anthocyanins and facilitating their polymerization. With regard to color evolution, the mixture of Monastrell with Merlot grapes was more appropriate than with Cabernet Sauvignon for aging wines in oak barrels. The extent of copigmentation was more important in young wines than in aged wines. This is mainly due to the self-anthocyanin monomer reactions in the case of young wines, whereas in aged wines copigmentation is mainly due to the reaction between the anthocyanins and other polyphenolic cofactors. Discriminant analysis showed the possibility of differentiating wines according to the aging time and the type of wine, with color parameters (color intensity, OD 620 nm, and OD 520 nm) being the most important discrimination variables in the first case and petunidin-3-glucoside and peonidin-3-glucoside contents in the second case.     

Combining sub-lethal heating and on-farm wastes: effects on <Emphasis Type="BoldItalic">Fusarium oxysporum</Emphasis> f.sp. <Emphasis Type="BoldItalic">cumini</Emphasis> causing wilt of cumin

In a 2-year field study, the effects of four heating regimes established by varying temperature or duration of heating on efficiency of on-farm wastes as soil amendments in controlling Fusarium oxysporum f.sp. cumini (Foc) causing wilt on cumin (Cuminum cyminum L.), were ascertained. Significant improvement in reduction of Foc propagules was achieved with the increase in duration and amount of heat. In 2000, mild heating under shade (heat level 4), 31.8–65.9% reduction in Foc propagules was estimated in all the amendments at 0–30 cm soil depth, which improved by 75.7–86.5% in the treatment where Foc-infested soil brought from the laboratory was exposed to direct heat (heat level 3) and amendments and irrigation were applied. Foc propagules were reduced by 76.6–88.3% when infested soil was exposed continuously to dry heat for 56 days (heat level 2), improving efficiency of amendments by 0.9–13.5% compared with heat level 3. After 56 days of exposure to dry heat, elevating the temperature by mulching amended soil with a transparent polyethylene film (50 μm thick) for 20 days (heat level 1) augmented reduction by 80.2–95.5%. In the second season, combining 0.04% of onion, Verbisina encelioides or mustard oil-cake with mustard residues (0.18%) improved the reduction in Foc propagules at all heat levels even at the lower soil depth. Maximum reduction (94.9–100%) in Foc propagules at heat levels 1 to 3 was achieved when residues of Verbisina were supplemented with those of mustard. These results suggest a new approach to improve the control of Foc by combining prolonged heating with on-farm wastes such as Verbisina residues and one summer irrigation.     

如何在热应激状态下给奶牛降温

热应激影响高产奶牛的生产与繁殖性能。在以色列,奶牛的受胎率冬季为50％,到夏季就降到20％以下了。夏季奶牛的发情行为也相对没有那么强,并伴随着繁殖率低、产犊间隔增加、生产效率较低以及造成供应乳品厂原奶的季节性问题等。在以色列,夏季所产牛奶的乳蛋白和乳脂含量降低,而体细胞数增加,造成牛奶质量的明显下     

Mass Production of Juveniles of the Fat Snook Centropomus parallelus in Brazil

A pilot‐scale trial to rear fat snook Centropomus parallelus through larval, weaning and nursery phases was conducted in Florianópolis, Brazil. Eggs (96% fertilization) from captive broodstock, induced to spawn using 50 μg/kg LHRHa were stocked in two 4,000‐L cylindrical fiberglass tanks at a mean density of 19.2 eggs/L. Nannochloropsis oculata was stocked with the eggs and maintained at a mean density of 0.5–1.0 ± 10⁶ cells/mL up to 31 dph (31 dph). Hatching averaged 90%. Larvae were fed rotifers Brachionus rotundiformis enriched with an oil emulsion from 3 dph to 36 dph (30–40 rotifers/mL) and Artermia meta‐nauplii enriched with Selco from 22 dph to 60 dph (mean 2.9 meta‐nauplii/mL). Weaning began at 45 dph with an artificial dry diet NRG (50% protein), supplied together with concentrated and enriched Artemia meta‐nauplii. No critical period of mortality was observed during larval rearing. During the 43 days of weaning and nursery, less than 1% mortality was recorded. Food conversion rate during nursery was 1.17, with a change in the coefficient of variation of mean total length of 1.3%. Specific total growth rate in weight was 13.0 %/d and mean growth in total length and total weight were 0.65 mm/d and 24.0 mg/d over the whole rearing trial respectively. Mean total length and total weight of juveniles were 57.6 ± 0.1 mm and 2.11 ± 0.12 g, respectively, and the length‐weight relationship was W = 8.29931 ± 10–⁵ TL^3.049607 (r= 0.9986). on 88 dph when the trial was terminated. The condition factor on 88 dph was 1.104. On 88 dph a total of 35,000 juveniles were harvested, overall survival was 25.5% with mean final density of 4.4 fishn and biomass of 6.9 kg/m³. The present trial demonstrated the feasibility of mass production of fat snook. Possible improvements necessary for commercial cultivation of fat snook C. parallelus are discussed.