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The relationships between wood anatomy in standing trees and the strength of boards were examined in Pinus radiata D. Don (thinned vs thinned and fertilized) at 2 contrasting sites. Fertilizer treatments were applied after mid-rotation thinning. Logs were taper sawn and boards, near the pre-treatment / post-treatment boundary, subjected to acoustic and strength assessment. Average wood property data from a 12-mm increment core obtained prior to harvest, was extracted from the relevant portion of the radius.In general, fertilizer resulted in lower density, higher microfibril angle (MFA) and slightly lower stiffness. However, stiffness was still relatively high as the affected wood was from the more mature portion of the radius. SilviScan density and MFA data were good predictors of stiffness. Acoustic measurements on boards were strongly correlated with board stiffness. Path analyses explained up to 45% of the variance in stiffness, as a function of estimated MOE and log sweep.

-Wood stiffness varies enormously both within and between trees, so it is inevitable that low-grade solid wood products are produced from some trees. Accordingly, it would be highly desirable to segregate logs to ensure that only those logs with predominantly high stiffness wood are processed into structural lumber products. This study examined whether sound flight velocity (m s -1 ) could be used as a direct measure of wood stiffness to allow such segregation. Trees of radiata pine were measured before and after harvest with a non-destructive acoustic device (stress wave timer) to see if there was a relationship between sound wave velocity in either standing trees or logs and machine stress-grades of boards derived from those trees and logs. The speed of sound along logs was sufficiently closely correlated with wood stiffness to allow logs to be sorted into classes. A highly significant and positive relationship was found for acoustic measurements made in logs and a weaker, but still significant, relationship existed for acoustic measurements made in standing trees. Such segregation of logs according to wave velocity measured in the field may save a large sawmill between A$1-4m each year. Acoustic methods may also be used as an indirect tool for selection provided the heritability of the measurements is high enough and there is significant genetic correlation with genetic values for wood stiffness. From another experiment we have estimated the heritability of several acoustic measures and hope to be able to estimate genetic relationships with wood quality soon. modulus of elasticity / wood, acoustics / sound speed / selection Résumé -Classement des grumes de pin radiata selon le module d'élasticité par méthode acoustique. Les variations de module d'élasticité du bois, aussi bien inter-qu'intra-arbre peuvent être considérables. Il est alors inévitable de trouver des pièces de qualité mécanique médiocre en scierie. Il serait donc tout à fait souhaitable de pouvoir classer les grumes de telle sorte que seules celles qui pourront donner des sciages de qualité soient orientées pour la production de bois d'oeuvre. Cette étude analyse la possibilité d'utiliser la vitesse de propagation du son dans le bois comme estimateur du module d'élasticité permettant un tel classement. Plusieurs pins radiata ont été mesurés avant et après abattage par une méthode non destructive afin d'analyser la relation entre la vitesse du son mesurée dans l'arbre sur pied ou la grume d'une part, et le classement mécanique sur machine des planches issues de ces grumes d'autre part. La corrélation positive et très significative mesurée sur grume est suffisamment élevée pour permettre le classement de ces grumes. Cette corrélation est plus faible, mais reste significative pour les mesures effectuées sur pied. Un classement des grumes effectué de cette façon sur chantier permettrait à une scierie de grande taille d'économiser de 1 à 4 millions de dollars australiens chaque année. Les méthodes acoustiques pourraient aussi être utilisées c...

A series of experiments was carried out on oat to test the efficacies of fluazifop and glyphosate against water-stressed plants, plants grown in low and high nitrogen (N), and plants treated with gibberellic acid (GA). In the laboratory, plants maintained at wilting point for 5 days before and 9 days after spraying with fluazifop (0.5 kg ae/ha) appeared healthy 32 days after herbicide application, while plants supplied with water throughout the experiment were completely chlorotic/necrotic and had main stem detachment from within the leaf sheaths. In the field, plants maintained unirrigated until 14 days after spraying with fluazifop (0.25 kg/ha) or glyphosate (0.18 kg ae/ha) showed greater tolerance of the herbicides than plants irrigated regularly. Under well-watered conditions in the laboratory and field, fluazifop (0.25 kg/ha) and glyphosate (0.18 kg/ha) were less toxic at low N than high N. Increased fluazifop activity at high N was associated with increased transport of herbicide to apical meristems. Addition of 200 μg GA into the leaf sheaths 2 days prior to spraying with fluazifop or glyphosate increased the efficacy of both herbicides at low N.

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