By David Karki
With the goal of reducing lodging in oats, SDSU Extension and a research team initiated a multi-location trial in 2018 growing season to study the effects of plant growth regulator (PGR) on oat performance. Oat is more vulnerable to lodging than other small grain crops grown in South Dakota and PGR is known for reducing height in grass species, thus helping in reducing plant lodging. Another variable ‘nitrogen levels’ was also added in the trial to study the effects of nitrogen level on yield and other agronomic characteristics.
The PGR ‘Palisade’ (a.i. trinexapac ethyl 12%) by Syngenta was used in this study. The labelled rate is 10.5/a oz to 14.4 oz/a with application timing ranging from plant growth stage Feekes 4 (leaf sheaths beginning to lengthen) to Feekes 7 (second node formation). We applied PGR on all nitrogen level plots with ‘control’ plots which did not receive any PGR adjacent to the treated ones. The experiment was conducted at the SDSU Northeast Research Farm by South Shore and SDSU Southeast Research Farm by Beresford. Both locations had soybean as a preceding crop.
In 2018, the NE Farm field was seeded with variety ‘Hayden’ on April 30th and the Palisade was applied on June 18th (approx. Feekes 6 or 1st node stage) at 14 oz/a rate. The field was harvested on August 8th. Plant height and lodging score (taken as percent lodged area per plots) measured at harvest were significantly affected by PGR but not nitrogen rates. Plant height was consistently reduced by PGR application and generally, we observed up to five inches of height reduction for plots applied with PGR. The range of plant height for PGR plots was 41 to 43 inches whereas, for the plots that were not applied with PGR, the range was from 45 to 46 inches. In most cases, the lodging score showed correlation with the plant height, i.e. the plots applied with PGR showed minimal lodging as compared to non-PGR plots. The lodging score ranged 0% (control plot with PGR) to 78% (236 lbs/a N without PGR). As expected, we observed a wide range of grain yields (108 bu/a to 159 bu/a), however, it was bit surprising that plots without any nitrogen yielded the highest which suggested that nitrogen from previous crop (soybean) plus soil test nitrogen of 56 lbs/a was adequate to produce 159 bu/a grain in 2018 growing season at NE farm.
Although, the SE farm showed similar results for plant height and lodging, the yields in general were significantly lower than NE farm which could be due to delayed planting and early growth heat stress caused by extremely temperature in May.
This study is supported by SD Nutrient Research and Education Council and will be continued in 2019 growing season.