Impact of Planting Date on Irrigated Grain Sorghum in Arkansas.

Grain sorghum is a crop with a lot of positive aspects for Arkansas producers.  It is typically used as a way to manage root-knot nematodes or glyphosate tolerant pigweeds.  Many producers consider grain sorghum to be a low input, low yield crop; however under proper management grain sorghum can yield exceptionally well.  One factor for maximum yields is planting date.  Little research in the Mid-South region has looked at the impact of planting date on grain sorghum yield.  Field studies were conducted from 2008-2013 at the Lon Mann Cotton Branch Research Station near Marianna, Arkansas to evaluate the impact of planting date on irrigated grain sorghum.  Each year, four widely grown commercially available hybrids were grown in four to five planting dates spaced approximately three weeks apart beginning in late March or early April and continuing until late June.  University of Arkansas Cooperative Extension Service management practices were used in all planting dates.  Plots were furrow irrigated as needed.  Greatest and most consistent yields generally came from grain sorghum that was planted in April.  Even with ample irrigation, yields tended to drop once planting date was delayed past Mid-May, which was likely a function of high day and nighttime temperatures.  Yields of June planted grain sorghum varied considerably more than earlier plantings and variation was mostly based on weather.