Differences in thermal tolerance among sockeye salmon populations

Climate change-induced increases in summer water temperature have been associated with elevated mortality of adult sockeye salmon (Oncorhynchus nerka) during river migration. We show that cardiorespiratory physiology varies at the population level among Fraser River sockeye salmon and relates to historical environmental conditions encountered while migrating. Fish from populations with more challenging migratory environments have greater aerobic scope, larger hearts, and better coronary supply. Furthermore, thermal optima for aerobic, cardiac, and heart rate scopes are consistent with the historic river temperature ranges for each population. This study suggests that physiological adaptation occurs at a very local scale, with population-specific thermal limits being set by physiological limitations in aerobic performance, possibly due to cardiac collapse at high temperatures.     

Venus: an isothermal lower atmosphere?

Use of Earth-based microwave data in extrapolating the atmospheric profile of Venus below the region probed by Mariner V and Venera 4 reveals an isothermal layer at 670 degrees +/- 20 degrees K that extends to an altitude of 7 +/- 2 kilometers. This model gives a value of 6054.8 kilometers for the radius of Venus, and agreement with brightness spectrum, radar cross sections, and results of microwave interferometry.     

The influence of physiological processes on tuber yield of potato clones (Solanum tuberosum L.): Stomatal diffusive resistance,stomatal conductance,gross photosynthetic rate,leaf canopy,tissue nutrient levels,and tuber enzyme activities

Summary Field measurements of stomatal diffusive resistance (DR), stomatal conductance (SC), gross photosynthesis (P_G), visual leaf index (VLI), petiole nutrient levels (%P, %K, NO₃−N), and tuber enzyme activities (ADPG pyrophosphorylase) were recorded during 1978 and 79 using 17 and 19 potato clones, respectively (Solanum tuberosum L.). Many clones differed significantly in DR, SC, and P_G. One clone (A6948-4) had significantly greater SC and P_G rates than all other clones. The measurements of DR, SC, P_G, and %K would appear to have limited value for rapid and extensive selection within potato breeding programs. Correlations are highly variable one season to the next, and several such physiological measurements would have to be combined to provide useful data for selection purposes. However, since measurements of DR, SC, and P_G varied significantly and were apparent determinants of tuber yield for some clones, such measurements have potential value for selecting clones to be used as parents in genetic crosses.

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Zusammenfassung Feldmessungen von stomatalem Diffusionswiderstand (DR), stomataler Leitf?higkeit (SC), Bruttophotosynthese (P_G), visuellem Blattindex (VLI), Stengelern?hrungsgraden (%P, %K, NO₃−N) und Knollenenzymaktivit?ten (ADPG Pyrophosphorylase) wurden in den Jahren 1978 und 79 17 bzw. 19 Kartoffelklonen (Solanum tuberosum L.) vorgenommen (Tabellen 1 und 2). Viele Klone wichen in DR, SC und P_G signifikant voneinander ab. Ein Klon (A6948-4) hatte signifikant gr?ssere SC-und P_G-Raten als alle übrigen Klone. Die meisten, aber nicht alle Klone wiesen w?hrend des Nachmittags im Vergleich zum Vormittag reduzierte SC- und P_G-Raten auf (Tabelle 1). Die SC- und P_G-Werte waren in beiden Jahren positiv korreliert (r=0,89 und 0,91, P<0,01). SC und DR waren negativ korreliert (r=−0,63, P<0,01). Im Jahre 1978 zeigten SC und P_G bei Verwendung von herk?mmlichen S. tuberosum-Klonen geringe Korrelationen und VLI eine hohe Korrelation (r=0,81, P<0,01) mit dem Knollenertrag. Im Versuch 1979, der verschiedene gp.andigena-Klone (Tabelle 2) einschloss, zeigten Sc und P_G positive Korrelationen (r=0,58 und 0,55, P<0,02) und VLI keine Korrelation zum Knollenertrag. DR war mit dem Knollenertrag negativ korreliert (r=−0,47, P=0,05). Die Aktivit?ten der ADPG Pyrophosphorylase in den Knollengeweben waren unter den Klonen stark variabel, aber sie korrelierten nicht mit dem Knollenertrag. In Uebereinstimmung mit Holm und Nylund (1978a, b): die Neigung des %K war mit dem Knollenertrag negativ korreliert (r=−0,52, P=0,01). Die Messungen von DR, SC, P_G und %K scheinen einen beschr?nkten Wert für eine rasche und umfassende Auslese innerhalb des Kartoffelzüchtungsprogramms zu haben. Die Korrelationen schwanken stark von einer saison zur andern, und einige solcher physiologischer Messungen müssten kombiniert werden, um nützliche Daten für Selektionszwecke zu erhalten. Da jedoch die Messungen von DR, SC und P_G signifikant variierten und offenbar Determinanten des Knollenertrages für einige Klone waren, haben solche Messungen potentiellen Wert für die Auswahl von Klonen, die als Eltern in genetischen Kreuzungen verwendet werden k?nnen.

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Résumé Des mesures au champ de résistance des stomates à la diffusion (DR), de conductance des stomates (SC), de photosynthèse brute (P_G), d’indice foliaire visuel (VLI), de niveaux de nutrition des pétioles (%P, %K, NO₃−N), et des activités enzymatiques des tubercules (ADPG pyrophosphorylase) ont été enregistrées en 1978 et 1979 respectivement sur 17 et 19 clones (Solanum tuberosum L.) (tableaux 1 & 2). De nombreux clones se sont révélés significativement différents quant à DR, SC, et P_G. Un clone (A6948-4) avait des niveaux significativement plus élevés pour SC et P_G que tous les autres. La plupart, mais pas tous les clones, avaient des niveaux plus bas pour SC et P_G pendant l’après-midi, comparés à ceux du matin (tableau 1). Les valeurs de SC et P_G étaient corrélées positivement les 2 années (r=0.89 et 0.91, P<0.01). SC et DR étaient corrélés négativement (r=−0.63, P<0.01). En 1978, en utilisant des clones deS. tuberosum conventionnels, SC et P_G étaient faiblement corrélés au rendement en tubercules et VLI fortement (r=0.81, P<0.01). Dans l’étude de 1979, qui comprenait plusieurs clones gp.andigena (tableau 2), SC et P_G étaient corrélés positivement (r=0.58 et 0.55, P<0.02) au rendement mais VLI n’était pas corrélé. DR était corrélé négativement au rendement (r=−0.47, P=0.05). Les activités des ADPG pyrophosphorylases dans les tissues des tubercules étaient très variables en fonction des clones, mais sans aucune corrélation avec le rendement en tubercule. En accord avec les résultats de Holm & Nylund (1978a, b), la diminution au %K était corrélée négativement au rendement (r=−0.52, P=0.01). Les mesures de DR, SC, P_G, et %K sembleraient donc avoir un intérêt limité pour la sélection rapide et extensive dans le cadre des programmes d’amélioration des pommes de terre. Les corrélations sont très variables d’une saison à l’autre, et il faudrait combiner plusieurs mesures physiologiques de ce genre pour fournir des données utilisables à des fins de sélection. Cependant, comme certaines mesures de DR, SC, et P_G variaient significativement et étaient apparemment déterminantes dans le rendement de certains clones, de telles mesures ont une valeur potentielle pour la sélection de clones qui seraient utilisés comme parents dans les croisements génétiques.

     

Specific gravity of Russet Burbank potatoes

Variability in specific gravity of Russet Burbank potatoes was documented in a single 32 hectare field. Maximum variation was 40 units among individual tubers within hills (one unit equals one part in 1000th of specific gravity measurement) and 15 units among hills. Field site variability of 10–15 units was common between sampled grid lines in the field; but bulked samples (truckloads) reduced the sampled variability to 8–10 units. When the samples were taken from bulked lots as opposed to single hill samples, the variability decreased. Grower lots, which were pooled samples from several truckloads, showed specific gravity differences of 2–7 units even though all lots were from the same field. These variations among specific gravity samples should be taken into account when considering total solids content in any lot of potatoes. Degree of russetting of the skin and hollow heart also influenced specific gravity measurements. Measured differences between peeled and unpeeled lots of 10 units in specific gravity corresponded to 2% difference in total solids content. Statistically, the variance of the peeled lot was one half that of the unpeeled lot, therefore, to minimize the measured differences due to skin type, peeled potatoes could be used for the specific gravity measurements.     

Sprout inhibition in storage: Current status, new chemistries and natural compounds

A major component of managing potato quality in storage is effective sprout inhibition. Sprouting causes increased weight loss, reduced tuber quality and impedes air movement through the potato pile. The primary method to control sprouting in storage is with postharvest applications of isopropylN-(3-chlorophenyl) carbamate (chlorpropham; CIPC). CIPC inhibits sprout development by interfering with cell division. However, a recent Environmental Protection Agency mandate, from the requirements of the Food Quality Protection Act (FQPA) of 1996, resulted in a reduction in allowable CIPC residue on fresh potatoes in the United States from 50 ppm to 30 ppm. This mandate coincides with tolerance reductions or restrictions for use of CIPC in other parts of the world. CIPC is an effective sprout inhibitor although factors such as storage conditions, application technology, and cultivar can impact that effectiveness. Alternative sprout inhibitors to CIPC continue to be evaluated. Essential oils (e.g., caraway, peppermint, spearmint, clove) or their components (e.g., s-carvone, eugenol), and hydrogen peroxide-based materials, physically damage the developing sprout and suppress sprout elongation. However, repeated or continuous application of these compounds may be necessary for efficacy. Substituted naphthalenes (e.g., dimethyl naphthalene, diisopropyl naphthalene) may help reduce the amount of CIPC applied and/or our dependency on CIPC for sprout suppression in storage. The objective of this review is to summarize the current use of CIPC for potato sprout inhibition in storage and to review the status of current research on other postharvest applied compounds or materials that may be used as alternatives for CIPC.     

不同Rht基因对小麦子粒品质的影响

多年结果证明Rht1、Rht2、rht3个近等基因系之间的子粒蛋白质含量差异不显著，而Rht3基因系的蛋白质含量显著高于前三者。Rht3基因系的子粒赖氨酸含量显著高于Rht2和rht系统，Rht10显著高于Rht1系，其他基因系之间无显著差异。Rh10基因系的面粉的沉降值显著高于Rht1,Rht8和Rht12,Rht3显著高于Rht1,Rht2和rht。Rht10和Rht3基因系面粉的湿面筋显著高于其他基因系。此外，同一基因系在不同的年限之间的品质性状表现有差异。