Black Oat Cover Crop Management in Watermelon Production Systems

Black oats (Avena strigosa Schreb.) were sown as a cover crop near Weslaco, TX (Lat. 26^o N), in Fall 2010.  The cover crop was allowed to senesce naturally and planted to watermelons in both the Spring and in Fall 2011. Spring-planted watermelons transplanted into mowed black oats (either bedded or non-bedded) suffered retarded early season development in vine and root weight, reduced root:shoot ratio, delayed fruit maturation, reduced yield, and average fruit weight compared to bedded watermelons transplanted on beds with or without black plastic.  Fall-planted watermelons transplanted into completely senescent black oats performed differently.  Early season growth of bedded melons was delayed in the conventionally planted beds compared to strip-tilled and chisel-planted watermelons which had higher leaf SPAD values, more leaves per plant, greater vine length, more blooms, and greater tendril attachment to oat residue compared to conventionally bedded plants.  Marketable season yield, marketable number, average weight (Chisel only), and soluble solids were higher in fruit from the conservation tillage systems.  Water replacement (70% vs. 90% ET_o) had no effect on marketable yield attributes or late season leaf stomatal resistance, but the higher replacement rate increased seasonal soil water profile content at 25, 50, and 0–100 cm depths.