Canopy reflectanoe plays an inoreasingly important role in orop management and yield prediction at large soale. The relationship of four speotrai refieotance indices with cotton {Gos-sypium hirsutum L.) biomass, leaf area index (LAI), and crop yield were investigated using three cotton varieties and five N rates in the irrigated low desert in Arizona during the 2009 and 2010 growing seasons. Biomass, LAI, and canopy reflectance indices (normalized difference vegetation index [NDVI], simple ratio [SR], near-infrared index [NIR], and ratio vegetation index [RVI]) were determined at different growth stages. The commonly used NDVI and the other three canopy reflectance indices explained over 87% variation in cotton biomass (all R^ > 0.87) and LAI {R^ > 0.93). Indices SR, NIR, and RVI ail had higher coefficients of determination {R^) compared to NDVI because these indices were not saturated at late growth stages. There was no significant relationship between lint yield and the spectral indices measured at eariy growth stages. However, the spectral indices determined at peak bloom showed significant correlations with lint yield. Indices SR, NiR, and RVI explained 56, 60, and 58% of variations in cotton lint yield, respectively, while NDVI only explained 47% of variation in lint yield. This study suggests canopy reflectance indices can be used to predict cotton lint yield at peak bloom and the accuracy of yield prediction can be significantly improved when SR, NIR, and RVI are used.
Hand harvested ‘Meeker’ red raspberries were held at 4°, 14°, and 25°C for up to 12 days using two types of sulfur dioxide generating pads. Visual mold ratings were lower for fruits held with either SO2 generator, but Howard Mold Count did not differ between the generators and the control fruits. Fruits stored with the generators were brighter and redder in color than controls when stored at 4°C. Irregular bleaching of anthocyanins from drupelets occurred when fruits were stored at 14°C or higher. Use of SO2 generators is not recommended for fresh market fruit or nonheat treated processing fruit due to the bleaching and due to SO2 residues in the fruit.
Winter injury is the greatest limiting factor in strawberry production in southwestern British Columbia and northwestern Washington. In recent years the problem has been accentuated by the susceptibility of the widely grown cultivar ‘Northwest’ to injury. During the winter of 1968-1969, conditions were such that severe injury occurred in strawberry plantings throughout the region. It was possible, therefore, to assess the relative winter hardiness of various cultivars and advanced selections, from the strawberry breeding programs in British Columbia, Washington and Oregon, which had been placed at 5 locations in 1968. All the cultivars or selections were more winter hardy than Northwest and several appeared to have an outstanding level of hardiness. Some of the more hardy selections have as good processing quality as Northwest and at least one is likely to replace it within the next few years.
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