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Hybrid rice varieties — range of options

Hybrid rice, first grown in China and available since the mid-1970s, is among the innovative agricultural developments that have enabled U.S. farmers to become even more productive.

Some 50 percent of that nation’s rice acreage is now in hybrids and hybrid rice acreage in neighboring India and other rice-producing countries is picking up.

In the United States, RiceTec — whose first commercial hybrid, XL6, was released in 2000 — is providing hybrid rice seed for the South. The company will have four hybrids available for 2010.

Delta Farm Press spoke with RiceTec’s Brian Ottis in mid-November. Ottis, who has been with the company for three years, works in southeast Missouri.

Explain the hybridization process and why hybrids are superior.

“Hybrid rice is similar to other hybrid crops. It has a phenomenon associated with it called ‘heterosis’ — otherwise known as ‘hybrid vigor.’ Heterosis is the result of a wide genetic cross between two distantly related parents.

“That’s opposed to a pure-line cultivar — where parents are fairly closely related — like we’ve been growing for years… The hybrid seed we plant provides more efficient photosynthesis and better disease resistance. So far, we don’t have to treat hybrid rice for blast, the most destructive rice disease. It’s also better suited against sheath blight disease.”

What about irrigation methods and hybrid rice?

Hybrids also have “a larger root system which means hybrids are less susceptible to drought. That means farmers with lighter/sandier soils like to grow hybrids because they can better withstand drier conditions prior to flood-up. Large rice fields can take a long time to flood. Many times, (conventional) varieties will suffer (waiting) for the flood. A hybrid will do better in that circumstance.

“That also opens up other potential. For example, hybrids are being grown under center-pivot (for more, see Rice under center pivots). We’ve had a lot of success with that.

“Growers are also growing hybrid rice with furrow-irrigation systems. Essentially, the hybrids are drilled on beds like you would soybeans then it’s row-watered with polypipe.

“2009 was great for that. Obviously, there was a lot of rain. But there were several yield reports from furrow-irrigated fields of over 190 bushels, dry.”

Discuss vigor, seeding rates and “sustainability.”

“With the hybrid vigor, you also have more robust growth. That allows a lower seeding rate because the hybrids can compensate for voids in the canopy more efficiently than a pure-line variety.

“In fact, due to a better seed quality and vigor in our seed, we will be recommending a 500,000-seeds-per-acre seeding rate for RiceTec hybrids going forward. That equates to 12 seed per square foot as opposed to (the previously recommended) 14 seed per square foot.

“With the improved seed, we’re still shooting for a final plant stand of eight to 10 plants per square foot. Our replant policy will remain the same: fields drill-planted under normal circumstances with less than five plants per square foot will be eligible for replant seed at no cost.

“More robust growth also lends itself to better weed competition. We’ve gotten several reports of growers who spend less money on herbicides. Also, there are savings with fungicides because of the excellent disease package.

“All of these characteristics lead into the ‘sustainability issue’ that is a hot topic in the rice industry, right now. Hybrid rice fits well because it can get by with less water, less pesticide load in the environment, less weed competition — a lot of advantages from an environmental standpoint.”

What about hybrid ratoon crops?

“This year, we’re getting a mixed bag — ratoon rice is kind of a moving target. There’s a lot that can happen in the first, main crop that can affect the second crop. But we do tend to get the best yields in the second crop in Texas and Louisiana.

“Because of the earliness of hybrids, we’ve had growers as far north as Jonesboro, Ark., that have made ratoon crops. In fact, a few years ago, there were a couple of southeast Missouri farmers that made a ratoon crop.

“2009 wasn’t a good year for (ratoon rice in the Mid-South) because it was so cool. To make it work, you need to get it planted early — around April 1 (in the Mid-South). The weather needs to be hot so the rice comes off fast. You also need a late fall.

“Typically, growers that try it farther north will put boards back in spills and let rain fall. They won’t spend a lot of extra money. Whatever is out there, they’ll harvest. It’s gravy, if you will.

“But hybrids tend to come off faster on the ratoon crop. They tend to green up faster, produce the panicle quicker than a (conventional) variety.”

A new hybrid to fit ratoon cropping.

“We have a new hybrid coming out, hopefully, for the 2011 planting season. It’s called Clearfield XP751 and is about six to eight days earlier than anything we have available now.

It’s the first true semi-dwarf hybrid we’ve released, only about 30 to 34 inches tall. It has very good resistance to lodging and it has the same good disease package of the other hybrids.

“That should offer considerable water savings since you’re shortening the season. Plus, it should open the possibility for more ratoon cropping farther north since it’s so early. In trials we’re seeing a significant yield advantage for it over our current hybrids. We’re very excited about this one.”

Any other new hybrids coming down the pipe?

“We don’t have any new hybrids for 2010. We’re looking at Clearfield 745, our new standard. It has better resistance to shattering, which has been an issue for hybrids in some areas.

“We’re offering Clearfield XL729, which has been out for a few years, now.

“We’ve also got XL723, our conventional hybrid workhorse. It’s been around since 2005 and offers really good yield and milling quality.

“In 2011, in addition to the 751, we’re looking at two others. One is Clearfield XP752, which will be the answer to some growers’ complaints. Hybrids tend to have a lot of pubescence and when it comes off it’s like fiberglass. It can be quite itchy for anyone handling the grain.

“But Clearfield XP752 is the answer to that, as a smooth-leaf/non-pubescent hybrid. It’s about two days later than Clearfield 745. We’re seeing good milling and yield potential with it.

“The second, XP754, will probably be released as a conventional hybrid. It’s a full-season hybrid, later than anything we’ve got now. It’s about a week later than XL723, doesn’t shatter, has very good milling quality and has about a 7 percent to 10 percent yield advantage over 723.

“XP754 will be similar to Wells in maturity. A lot of growers have big planting equipment and try to plant as much as they can as fast as they can. This hybrid, being later, will allow them to spread out harvest. That way there won’t be a lot of rice ready at the same time.”

A review of the 2009 growing season…

“In southeast Missouri, where I work, there were growers that had record yields. But 2009 was very odd. Typically, long-term yield data says the earlier you plant the better the yields.

“But this year it was almost a Bell curve. The early rice that was planted in early April before the rains started went through a cool snap and cloudy weather as the grain was filling. That led to a lot of blanks. That affected an area from Newport, Ark., all the way to Butler County in Missouri.

“Then, the rains hit and growers weren’t able to plant more until the last week of April. Then, it rained more. Rice that survived those rains did really well — our best yields came from rice planted the fourth week of April and first two weeks of May. Fortunately, the majority of our rice was planted in that time frame.

“Any rice planted in late May/early June that wasn’t flooded early went through really cold weather at flowering. We’re hearing some low yields because the rice didn’t fill. The heads came out and there are a bunch of blanks. That was the case in both hybrids and (conventional) varieties.

“This year, we had several months of near-record cool temperatures. That slowed the crop growth and affected yields. However, milling quality was excellent due to the cool weather during grain fill for the early- and mid-planted rice.”


TAGS: Rice
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