In California, most acreage is devoted to high quality medium grain varieties. In 2023, over 94% of the acreage was grown to medium grains. There are currently six medium grain varieties to choose from: very early (M-105), early (M206, M-209, M-210, and M-211), and late-maturing (M-401 – a premium medium grain). Here are some things to consider when making a choice.
M-105 is the earliest variety; although it is only 1-2 days earlier than M-206 in the northern part of the valley but it is 3-5 days earlier in the southern cooler parts of the valley. It also has excellent yield potential. Last year it had the highest yields in our yield contest with a yield of 132.5 cwt/ac. It also tends to yield the highest in our variety trials located in the southern portion of the valley (south of hwy 20). It is an excellent choice to plant at the start of the season in order to get an early start on harvest. The knock on M-105 is that it can lodge; however, in our variety trials (and other trials at the Rice Experiment Station), there is no indication that its lodging potential is different than M-206.
M-206 and M-210 are nearly identical except that M-210 has blast resistance. They are both early varieties and stable across environments. In areas with blast, or if dry seeding, M-210 is an excellent choice. In 2023, blast was wider spread than normal. For growers that have only used M-206, try using M-210 on a field and see how it compares. You should have very similar results.
In terms of yield potential, M-209 and M-211 have the highest yield potential. M-211 regularly out yields other medium grains by 1-3 cwt/ac in our variety trials in the northern part of the valley (north of hwy 20). Both M-209 and M-211 are longer in duration than M-206 and neither are well suited to cooler areas (M-209 being the least suited). Duration is also important when thinking about water limitations as they require more water to irrigate. Achieving good milling quality is one issue with these varieties. Milling quality drops rapidly when harvest grain moisture drops below 20%. Given this, it may not be wise to plant these varieties on a large number of acres where a timely harvest may be difficult. On a positive note, these varieties are less prone to lodging. This is partly due to thicker tillers. Some growers indicate that managing the rice straw in M-211 is harder than for other varieties. Finally, where kernel smut is an issue, M-209 is one of the more susceptible medium grains.
Finally, California's first herbicide resistant variety M-521 has been approved for release. However, seed production for this variety will not proceed until the herbicide is approved.