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Fluid Journal : Summer 2015
13 The Fluid Journal Summer 2015 Figure 2. Sorghum grain yield, in bu./acre, under diverse cropping systems approaches at Scandia, Ottawa, and Rossville, 2014 growing season. Treatment description: 1= Kitchen Sink (KS); 2= Plant Density (PD); 3= Row Spacing (RS); 4= Pre-plant nitrogen only (Pre-N); 5= Fungicide/Insecticide (F/I); 6= Micronutrients (Micros); 7= Plant Growth Regulator (PGR); 8= N and Phosphorous (P) (NP); 9= Chloride (Cl); 10= Farmer Practices (FP); 11= KS + extra 50 lbs N/acre (KS+N). statistically significant yield difference from all treatments versus the check (P = 0.07), a common-practice approach (treatment 10), Figure 2. Grain harvest index (HI) did not show any significant trend at Scandia and Ottawa, with overall grain HI values below 55 units. At Rossville, grain HI for treatment #1 was greater than 60 units, which demonstrates a superior biomass partition to the grain as compared with the whole plant biomass (above-ground biomass) (Figure 3). The farmer practice (FP, treatment #10) depicted the lowest grain HI coefficient, 56 units. The lowest efficiency in partitioning biomass to the grain was correlated to the inferior yield obtained for this treatment (FP, treatment #10) at the end of the growing season (Figure 3). Individual plants were measured (approximately 1,500 plants for two sites) in nondestructive areas for each treatment combination. Various morpho-physiological measurements were taken primarily at V5 (vegetative period) and at R1 stages (reproductive period). The plant height measured from the stem base to the collar of the uppermost leaf and stem diameter by recording maximum diameter at the stem base. The information collected from the plant height and stem diameter was used to calculate the allometric relationship between the per-plant stem volume [estimated via the cylindrical formula-based, stem volume calculation = 3.1416 *(stem diameter/2)* plant height]. This approach was previously used for estimating biomass for corn, but as far as the extent of our knowledge, it was never implemented for sorghum. The stem volume parameter (calculated using the plant height and stem diameter measured at flowering) was correlated with the per-plant dry mass values obtained in sorghum plants for all treatment combinations at Scandia and at Ottawa (Figure 4). The correlation presented for the above-mentioned association can be used as a pragmatic “Further site x year evaluation is needed to confirm findings.”