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Yield and quality of conventional and brown midrib (BMR) pearl millet with different establishment dates or harvested at different maturities.

M. J. Aguerre

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06-24-2020

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Abstract:

W41
Yield and quality of conventional and brown midrib (BMR) pearl millet with different establishment dates or harvested at different maturities.
M. Oskey1, B. Stancil2, M. J. Aguerre*1. 1Department of Animal and Veterinary Science, Clemson University Clemson, SC, 2Variety Testing and SC Crop Improvement, Clemson University Clemson, SC.

The main objectives of these studies were to evaluate the yield, composition and digestibility of conventional and brown midrib (BMR) pearl millet (PM) with different establishment dates or harvested at different maturity stages. A second objective was to evaluate the impact of mixing PM with cowpea on measured variables. Two trials were conducted in field plots (1.5 m � 6.1 m) as randomized complete block designs with a split plot arrangement of treatments. In trial 1, 2 varieties of PM (conventional and BMR) were planted at 2 different dates (14d apart) and harvested at early heading stage. In trial 2, 2 varieties of PM (conventional and BMR), mixed or not with cowpea were harvested at PM boot or heading stages. Samples from both trials were analyzed for CP, NDF, sugars (as % DM) and 30-h in vitro NDF digestibility (IVNDFD as % NDF). In trial 1, dry matter yield was numerically lower for BMR compare with conventional PM (4,255 vs. 3,875 kg/ha, P = 0.16), but delaying establishment significantly (P < 0.01) reduced DM yield by 23%, regardless of PM variety. Nutrient composition was similar between PM varieties (15.8% CP, 52.0% NDF, and 7.0% sugars). However, BMR had higher IVNDFD (66.3 vs. 63.6%) compared with the conventional variety. In Trial 2, DM yield was 8.3% lower for BMR compare with conventional PM (3,266 vs. 3,875 kg/ha, P = 0.07). Similarly, mixing PM with cowpea tended to also reduce DM yield by 8%. Harvesting at heading stage numerically increased DM yield by 5.3%. Pearl millet with the BMR trait had a higher IVNDFD, regardless of mixing it or not with cowpea (64.6 vs. 60.0%; P < 0.05). More mature PM resulted in a 7.3% lower IVNDFD (59.9 vs. 64.8%; P = 0.04). Nutrient composition was similar between forages (51.9% NDF, and 8.5% sugars), but cowpea increased CP level (14.2 vs. 15.3%, P = 0.01) when mixed with both PM varieties. Results of this studies suggest that BMR PM is more digestible than conventional but at expenses of lower DM yield. Planting date and plant maturity are important tools to manipulate PM yield and quality but mixing cowpea with PM had small effects on quality at expenses of yield.

Keywords: digestibility, summer annual, forage.