As the 2007 rice crop comes to an end, cultivar selection decisions for 2008 are at the forefront. The number of rice cultivars to choose from is small compared to soybeans and corn, but cultivar selection and placement are key components in maximizing yields and returns.
To help rice producers make decisions for 2008, “Mississippi Variety Trial” data collected in 2006 and 2007 are summarized below.
Combating red rice is still a major issue, made clear in 2007 because seed from Clearfield cultivars was limited. Clearfield technology will be a vital tool to keep red rice-infested acres in production.
Averaged over 2006 and 2007, Clearfield XL729 has shown a 31 percent yield advantage over CL-161 and CL-171AR. For the same time period, no yield difference was detected between CL-161 and CL-171AR.
Furthermore, CL-161 and CL-171AR produced similar yields at over 20 locations. Neither cultivar outperformed the other more than 3 to 4 bushels per acre.
CL-161 did have an advantage to other Clearfield cultivars with respect to whole milled rice. Whole milled rice of CL-161 was 3.8 percent better than Clearfield XL729 and 0.6 percent better than CL-171AR. One disadvantage to Clearfield XL729 was that its average height was 5 inches greater than CL-161 and CL-171AR.
Clearfield XL730 and Clearfield XP745 responded comparably to Clearfield XL729 in rough rice and whole milled rice yields; however, Clearfield XL730 has more shattering potential. Considerable yield losses were observed with Clearfield XL730 due to excessive winds from Hurricane Katrina in 2005.
Plant height is a disadvantage for Clearfield XP745 — it averaged 2.5 inches taller than Clearfield XL729 and 8 inches taller than CL-161. As a result, the lodging potential with Clearfield XP745 is higher than Clearfield XL729, CL-161, or CL-171AR. In two strip trials comparing CL-161 and CL-171AR, CL-161 showed more susceptibility to lodging than CL-171AR.
In comparisons of conventional cultivars, XL723 demonstrated a 14 percent yield advantage over Cocodrie and Wells. Whole milled rice for XL723 was 0.5 percent lower than Cocodrie, while Wells was 4.4 percent lower than Cocodrie.
XL723 averaged 2 inches taller than Wells and 6 inches taller than Cocodrie. XL723 would fit well on lighter soil that has recently been land-formed, as well as areas with greater blast potential.
In one year of evaluations, XP744 produced equivalent rough rice and whole milled rice yields to XL723, but a disadvantage of XP744 compared with other cultivars is that it averaged 3 inches taller than XL723 and 9 inches taller than Cocodrie.
Clearfield XL729 and XL723 have very similar disease resistance packages (moderately susceptible to sheath blight, moderately resistant to straighthead, and moderately susceptible to kernel smut). However, in some trials, hybrids that received a fungicide application to prevent/control sheath blight produced higher grain yields. Therefore, it should not be assumed that a fungicide will not be needed with a rice hybrid.
Hybrid cultivars have proven to have the capacity to provide a yield advantage compared with traditional inbred cultivars. However, before finalizing planting plans, one must ask, “Can I capitalize on the yield advantage?”
In general, inbred cultivars are considered to have more standability in the field than hybrids. This means that rough rice and whole milled rice yields will generally be more stable in a production setting when weather and harvest logistics are considered.
The longer a hybrid remains in the field past its optimum harvest window (16 to 20 percent grain moisture), the more susceptible it becomes to lodging and/or shattering, and poor grain quality. These factors will reduce net returns by decreased yield, loss of milling premiums, and decreased harvest efficiency.
Rice can be planted at a much more rapid pace than it can be harvested. Harvest strategies must be considered before planting decisions are made in 2008, especially where large acres of hybrid rice are being considered.
To maximize the potential returns that hybrid rice offers, growers should consider planting hybrids first so they can in turn be harvested first at near-optimum grain moisture.
Compared to conventional inbred lines, the hybrids will mature approximately three to five days earlier. At the farm-scale level, cultivars should be planted in the following order: XL723, Clearfield XL729, Cocodrie, Wells, CL-171AR, and then CL-161.