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Row orientation and configuration effects on canopy light spectra and corn growth

Karlen, D.L., Kasperbauer, M.J.
Applied agricultural research 1989 v.4 no.1 pp. 51
Zea mays, canopy, light, crop yield
Recent popular-press articles have recommended planting rows in a north-south (N-S) orientation. However, effects of row orientation and configuration on light spectra within corn (Zea mays L.) canopies and the resultant growth response are not well defined. Field studies were conducted in 1985 and 1986 on Norfolk (fine-loamy, siliceous, thermic Typic Paleudult) loamy sand near Florence, SC, to measure those effects. Corn was planted in single rows spaced 76 cm (30 in.) apart and in twin rows spaced 19-57-19 cm (7-23-7 in.) apart. Rows were oriented in a N-S or east-west (E-W) direction. Canopy light spectra, vegetative response at growth stages (g.s.) V6 and R2, days to silking and tasseling, yield, and yield components were measured. Far red:red light ratios were calculated from spectral data. Leaf area, stalk length, and stalk diameter at g.s. V6 were not affected by row orientation or configuration. Rows planted in an E-W orientation yielded more than those planted N-S in 1985 but less in 1986. Row orientation has been shown to affect root and shoot development. This reversed yield response to orientation was presumably the result of early water stress in 1985 vs. late-season water stress in 1986. Previous studies showed an advantage for planting twin rows when compared to single rows spaced 96 cm (38 in.) or more apart, but there was no apparent advantage for twin rows when compared to single rows spaced 76 cm (30 in.) apart. These results suggest that for irrigated or nonwater stressed corn, maximum yield will occur when rows are spaced approximately 76 cm (30 in.) apart and planted in a N-S orientation.