Winter Wheat Yield Response to Wide Rows Varies By Year in the Southern Ohio River Valley

Abstract

Research was conducted for three seasons (2008‐2009, 2009‐2010, and 2010‐2011) on soft red winter wheat in row widths of 3.75, 7.5, and 15 inches at two locations in the southern Ohio River Valley. Wheat in all row widths was seeded with a small‐plot drill at the standard rate of 35 seeds/ft2. A lower seeding rate of 25 seeds/ft2 was compared to the standard seeding rate in 15‐inch rows. Three cultivars (‘Beck's 122,’ ‘Branson,’ and ‘Pembroke’) were tested the first two years but there was no interaction with row widths. Only Pembroke was tested in the final season. Wheat yields in 7.5‐inch rows were greater than wheat yields in 15‐inch rows in one out of three seasons (two out of four environments). Yields of wheat in 3.75‐ and 7.5‐inch rows were not different. The lower seeding rate did not reduce yields in 15‐inch rows. Wheat in 15‐inch rows had lower test weights in several comparisons. Partial economic returns were $50/acre greater for wheat in 7.5‐inch rows in 2008‐2009 but no differences were observed in the other two seasons.

Wheat Sown with Narrow Spacing Results in Higher Yield and Water Use Efficiency under Deficit Supplemental Irrigation at the Vegetative and Reproductive Stage

“…Improved grain yield under narrow row spacing is likely the effect of less evaporation due to the higher number of tillers and canopy cover (i.e., higher LAI), and the small soil surface exposed to the sun relative to the wider row spacing. The positive effects of narrow row spacing in improving wheat outputs have also been previously reported by different researchers [12,27,28,[44][45][46]. They also reported that in wider row spacing, an improvement in the number of grains per spike and the 1000-grain weight was due to less competition for light and resources among plants compared with narrow row spacing.…”

“…In this study, SSI and DSI during the vegetative stage were clearly dominant over DSI during the reproductive stage, with higher gross and net income and BCR (Table 5). Further, among the different row spacings tested, the higher BCR and economic returns resulting from the narrow row spacing in this study (Table 5) and in previous studies [45] indicate that it is a viable agronomic tool to improve wheat outputs in water-limited environments. Similar results regarding improvements in gross income, net income and BCR under water deficit during the reproductive stage with narrow row spacing have recently been reported [12].…”

“…They also reported that in wider row spacing, an improvement in the number of grains per spike and the 1000-grain weight was due to less competition for light and resources among plants compared with narrow row spacing. Nonetheless, even a higher grain count and 1000-grain weight under wider row spacing could not compensate for the yield losses of wheat due to the reduced plant population under SSI and DSI conditions in this study and in several previous studies [12,[44][45][46][47].…”

“…Several earlier studies reported that increased wheat yield with narrow row spacing was due to a significant increase in the population of productive tillers [44][45][46]. It is likely that the competition for moisture and solar radiation was not too intense among the wheat plants in our study.…”

Evaluation of Wheat Planted on 15-Inch Row Spacing in Eastern Kansas

“…In northern climates where moisture is less of a limiting factor as length of growing season, narrow 3.5‐inch rows in winter wheat in Canada (8) and narrow 6‐inch rows with spring wheat in Montana (2) have resulted in greater yields than wider rows. Lee and Herbek have shown an advantage to narrower rows 1 out of 3 years with soft red wheat varieties that tiller well when grown in the greater moisture and more moderate conditions of the Ohio River Valley (5). Joseph et al (4) had greater yields with 4‐inch rows than with 8‐inch rows with soft red winter wheat at three location years in the Coastal Plain of Virginia.…”