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Digital imaging and analysis was used to quantify and characterize the light exposure patterns of photosensitive paper tubes placed in representative cluster positions in two grape (Vitis vinifera L.) canopies: a minimally pruned and a vertically trained canopy. Blue pixel values of the captured images had a negative correlation with the log of irradiance from an integrating quantum sensor (r 2 = 0.9308). The spectral response of the photosensitive paper was not measured. Histograms of incident light distribution on individual paper tubes were developed using imaging software. Histograms were able to quantify the distribution of incident light on individual tubes and were clearly related to the tube's exposure in the canopy. Average population curves of pixel light distribution of 20 tubes in each canopy were able to differentiate the typical cluster light environment in the two canopies. Tubes in the minimally pruned canopy had a larger proportion of their surface exposed to irradiances > 50 µmol·s -1 ·m -2 and 65% higher average irradiance than the vertical canopy. Image analysis of photosensitiv e paper appears to be a workable method to record the distribution ofincident light in plant canopies and may have utility in a range of ecological studies. The light environment of grape clusters can have pro- nounced effects on grape physiological processes and fruit and wine composition. Grape acidity, aroma, flavor, color, and phenolic composition are influenced by light. We have been investigating the effects of sunlight on the phenolic composi

Publisher Summary This chapter describes the reversed-phase high-performance liquid chromatography (HPLC) methods for the analysis of wine polyphenols. The analysis of phenolic compounds in any sample is a complex issue for a number of reasons. There are a number of well-established procedures designed to analyze all phenolic compounds as a single value (total phenol) or specific classes (i.e., total flavan-3-ol), but in every case there are differential responses (based on mass or molarity) related to different functional groups. The variability of the response can be small or large depending on the sample. The three procedures described in this chapter are (1) pH shift procedure, (2) low pH procedure, and (3) polystyrene column. Comparing the three methods, two silica gel reversed-phase systems have very similar elution orders, whereas the polystyrene column has a quite different pattern. In the latter case, polar anthocyanins and hydroxy cinnamates come out earlier, whereas nonpolar flavonols come out later. Thus, HPLC methods can separate major small phenolic constituents of wine in hour-long separations.

Digital imaging and analysis was used to quantify and characterize the light exposure patterns of photo-sensitive paper tubes placed in representative cluster postions in two grape (Vitis `vinifera L.) canopies: a minimally pruned and a vertically trained canopy. Blue pixel values of the captured video images had a strong negative correlation with the log of irradience from an integrating quantum sensor (R2=0.9308). Histograms of incident light distribution on individual paper tubes were developed using imaging software. Histograms were able to quantify the spatial distribution of light on individual tubes and were clearly related to exposure in the canopy. Average population curves of light distribution were able to differentiate the typical cluster light environment in the two canopies. Tubes in the minimally pruned canopy had a larger proportion of their surface exposed to irradiences greater than 50 μmol s-1m-2 and 65% higher average irradience than the vertical canopy. Image analysis of photo-sensitive paper appears to he a workable method to record variation in spatial and temporal light in plant canopies.

One- and two-year-old `Pinot noir' grapevines were irrigated with Hoagland's nutrient solution and shaded with 60% shade cloth to investigate the effect of shading on inflorescence necrosis (IN), tissue ammonium, and nitrate status. Shading increased IN, tissue ammonium, and nitrate concentrations of laminas, petioles, and rachis in two-year-old vines. IN was positively correlated with tissue ammonium and nitrate levels. In one-year-old vines, tissue ammonium and nitrate concentrations were increased by shading in most tissues except for nitrate in tendrils and old roots. Tissue ammonium correlated with nitrate concentration in various tissues after anthesis in one-year-old vines and in laminas, petioles, fruit, and rachis of two-year-old vines. Elevated tissue ammonium in rachis has been suggested as a possible cause of IN.

The saline load test is a popular method to demonstrate gastric retention. This technique, however, does not permit evaluation of volumes contributed by gastric secretion. We have studied 11 normal subjects and 7 patients with pyloric outlet obstruction using a dyedilution technique. We measured simultaneously rates of water secretion, fractional emptying rates, total intragastric volumes, and the fractions of gastric volume contributed by gastric secretion both during fasting and following a 250-ml water load. Total intragastric volume was significantly increased in patients with outlet obstruction compared to normal subjects both during fasting and following the water load (P less than 0.01). This increase resulted from significantly increased water secretion (P less than 0.01) combined with significantly decreased gastric emptying (P less than 0.01). Thus, gastric retention produced in patients with outlet obstruction by delayed emptying appears to be magnified by gastric hypersecretion of water. These data in no way invalidate the use of the saline load test in the diagnosis of gastric retention states, but help define the role of gastric secretion in the residual volumes measured following the load.