An evaluation of estimating and indexing methods to simplify the determination of management treatment effects on raspberry yields

Abstract

Kowalenko, C. G. 2003. An evaluation of estimating and indexing methods to simplify the determination of management treatment effects on raspberry yields. Can J. Plant Sci. 83: 141-147. The effectiveness of using several proposals to estimate or index yield and size of raspberries as an alternative to picking berries as they ripen was examined in two field plot trials over two seasons at two locations in south coast British Columbia. The evaluation included examination of general correlations of the proposed estimate and index values with fresh picked yield, comparison of the significant nutrient and inter-row management treatment effects on proposed method values with effects on fresh picked yield values, influence of individual cane variability to distinguish significant treatment effects, and the effect of N on plant components used to derive the estimate and index method. Correlation coefficients for all yield estimate and index method values with fresh picked yields were generally good. Crop management treatment effects determined by the estimate and index values, however, were not the same as determined by harvesting the berries as they ripened. This showed that the estimate and index method values were biased relative to picked yield. Cane-to-cane variability within individual treatment plots was sufficiently large that differences between treatments had to be greater than 10 to 15% to be significant at P < 0.05 when five canes were randomly sampled for index component measurements to represent the plants in the plot. The five canes sampled for each plot were 5 to 10% of all the floricanes in the plots of this study. The concentration and biomass N measurements that were possible on the floricane components that were sampled for the index methods showed that management treatments of the two trials of the study could have influenced berry development, and hence contributed to the bias of the estimate and index method values relative to fresh picked yield. Although the estimate and index methods were generally quite well correlated with fresh picked yield, caution is advised when they are used directly as alternatives to fresh picking to evaluate crop management treatment effects on berry yield. Further knowledge about the physiological changes that occur during berry ripening may provide opportunities to improve the estimate and index measurements. On a comparé plusieurs méthodes servant à estimer ou à indexer le rendement des framboisiers et le calibre des fruits à la technique qui consiste à cueillir les baies au fil de leur développement. L'expérience a duré deux saisons et s'est déroulée sur deux parcelles, à deux endroits de la côte sud de la Colombie-Britannique. Pour évaluer les méthodes en question, on a analysé les corrélations générales entre les valeurs estimatives et les indices proposés et le rendement réel à la cueillette, comparé les effets importants des apports nutritifs et du traitement des rangs sur ces valeurs à leurs incidences sur le rendement réel à la cueillette, établi l'influence...

Soil Inorganic Nitrogen Content and Indices of Red Raspberry Yield, Vigor, and Nitrogen Status as Affected by Rate and Source of Nitrogen Fertilizer

“…Dean et al (2000) found dry weight of the fruiting clusters to be well correlated to estimated berry yield using the method of Daubeny, Dale, and McGregor (1986). Kowalenko (2003) found whole-floricane biomass to be a better indicator of berry yield than Numeric value is field number; letters A to C refer to 1994 to 1996, respectively. Trials on the same field were at adjacent locations in different years.…”

“…However, few trials had a significant positive response to rate of N fertilization by fruiting-cluster biomass or whole-floricane biomass, indices of relative crop yield (Dean et al 2000;Kowalenko 2003), and no trial had a significant positive response for both parameters. Similarly, few trials had a significant positive response to the rate of N fertilization by indices of crop vigor including primocane length, primocane diameter, or mean primocane dry weight (Zebarth et al 1993;Dean et al 2000).…”

“…Biomass of fruiting clusters (Dean et al 2000) and of whole floricanes (Kowalenko 2003) were used as indices of relative berry yield. Primocane length and diameter and mean primocane dry weight were used as indices of primocane vigor (Zebarth, Freyman, and Kowalenko 1993;Dean et al 2000;Rempel, Strik, and Righetti 2004).…”

“…This lack of response to N fertilization may be due to several factors: a relatively low crop N demand due to limited plant density (Kowalenko 1994), a large supply of N from soil N mineralization, particularly where manure was applied (Dean et al 2000), difficulty in measuring crop response to N-fertility treatments due to high inherent variation in the crop (Kowalenko 2003), or to the ability of Rubus species to remobilize significant quantities of N from storage tissues (Mohadjer et al 2001;Rempel, Strik, and Righetti 2004). Using 15 N, Rempel, Strik, and Righetti (2004) reported that increasing fertilizer-N rate did not significantly increase plant N uptake but increased the proportion of N taken up from fertilizer and decreased the proportion of N from soil and from storage tissues.…”

Accumulation and distribution of micronutrients in Willamette red raspberry plants

“…The miscellaneous fractions were immature portions that could not be distinguished as specific components and accounted for only a very small proportion of the plant. The fruiting branchlets or fruit clusters (Kowalenko 2003), included the secondary branch (pedicel) off the lateral holding the buds, flowers and unripe berries. Berries were picked at 2-to 4-d intervals as they ripened.…”