Sign up for email alerts of new Fluid Journal issues!
Fluid Journal : Summer 2015
12 The Fluid Journal Summer 2015 Table 5: Stand counts for each treatment combination at all sites, 2014 growing season. Treatments Rossville Ottawa Scandia -plants in 17.5-ft row length- 1 43.4 43.6 40.4 2 29.4 38.2 46.8 3 81.8 85.6 42.4 4 43.2 41.8 43.4 5 42.2 43.2 35.8 6 42.2 43.4 27 7 42.8 43 27.8 8 41.8 42.8 28.6 9 42.6 43.8 29 10 60.8 54.2 32.6 11 43.4 42.4 34.4 C.V. 3.49 12.32 36.72 P-value <0.0001 <0.0001 0.1883 C.V. = coefficient of variation (%). Table 6: Crop phenology in calendar dates for all sites, 2014 growing season. Plant Phenology Rossville Scandia Ottawa Planting Date 19-May 22-May 26-May V-5 growth stage 27-Jun 2-Jul 1-Jul Flowering 1-Aug 4-Aug 8-Aug Mid-Reproductive 29-Aug 2-Sep 11-Sep Harvest 26-Sep 14-Nov 30-Sep Figure 1. Seasonal precipitation distribution (expressed in inches per 15-day time interval) at Ottawa, Rossville, and Scandia sites for sorghum crop during the 2014 growing season. days of duration of this phonological time interval. Weather information at all sites was recorded and seasonal precipitation distribution, expressed in inches, was documented throughout the entire growing season (from planting to harvest time) for the sorghum crop (Figure 1). At Ottawa, low precipitation (~3 inch) was registered from mid- July to mid-August, which affected the flowering period (greater grain abortion), with a similar situation for Scandia from mid-June to the end of July (Figure 1). Results Sorghum grain yields were highly variable within the treatments evaluated and between experiments. A descriptive statistic for the parameter was performed, which demonstrates the dispersion of the yield distribution from all replications at each site (Table 7). The site most impacted by the drought stress experienced during the flowering time was the Ottawa study (Figure 1) with high variability on minimum and maximum yield, which was documented in the high CV number (close to 24%, Table 7). Minimum CV% was recorded at Rossville, highly influenced by the irrigation component. For Scandia, the treatments evaluated did not present any significant difference for the yield factor (P=0.89). One of the lowest grain yields, 103 bu/A, was obtained when common practices were implemented (treatment #10) whereas yield was maximized at 115 bu/A when the “kitchen sink” approach was employed (treatment # 1). Although treatment was not statistically significant, the grain sorghum yield gap was 12 bu/A when high (treatment #1) vs low (treatment #10) input costs were compared (Figure 2). In Ottawa, the cropping system approach did not influence sorghum grain yields, which may be related to the low yield potential explored in this location (reproductive-stage drought stress) (P =0.99). In Rossville, the maximum yield gap documented between the highest- yielding treatment (“kitchen sink” without chloride application, treatment 9) and lowest-yielding scenario (check, treatment 10) was close to 20 bu/A (135 vs 114 bu/A, respectively). The diverse systems evaluated did not differ in sorghum grain yield, with a slightly Table 7: Descriptive statistics (mean, minimum, maximum, and coefficient of variation, CV) on yield parameter, expressed in bushels per acre, for all sites, 2014 growing season. Field Site Mean Yield Min. Yield Max. Yield Coefficient of Variation - bushels per acre- % Scandia 109 82 139 13.7 Rossville 129 101 151 8.3 Ottawa 68 38 99 23.8