Variety Trials - 2008




Home.gif (3162 bytes)

Next.gif (3180 bytes)

Back.gif (3162 bytes)

Project Leader and Principal  Investigators

James E. Hill,
UC Cooperative Extension Specialist, Dept. of Plant Sciences, UC Davis


Sixteen on-farm rice variety evaluation trials were conducted throughout the rice-growing regions of California in 2008 by UC Cooperative Extension in collaboration with the plant breeders at the Rice Experiment Station.  These on-farm trials perform an essential role in exposing standard, advanced and preliminary varieties to a range of environments, farmer practices and disease levels.

Six similar tests were conducted at the Rice Experiment Station, two from each maturity group.  Average yields across varieties and locations in the advanced line tests ranged from 9,790 pounds/acre in the very early trials to about 8,350 pounds/acre in the early tests.  In the intermediate-to-late test, the advanced lines yielded more than 9,660 pounds/acre.

Planting of the earliest rice fields was on schedule, with few rain delays experienced during the remainder of the season. Lack of early spring rains allowed for early field preparation. Several advanced lines in 2008 produced high yields, and demonstrated advances toward important breeding goals, such as disease resistance and grain quality.

Testing advanced and preliminary lines under a variety of conditions remains a critical aspect of releasing varieties adapted to changing cultural practices, markets and pests.

The long-term, rice-cropping systems experiment on stand establishment continued for a fifth year at the Rice Experiment Station.  Five different methods of rice stand establishment are being evaluated for weed control and fertility management. In 2008, after four years of testing five different stand-establishment systems, the systems were rotated to examine the impact of rotation on weeds. This work is described in more detail below and in other sections of this report.

Very early tests

Ten advanced breeding lines and seven commercial varieties were compared in four very early advanced breeding tests.  Additionally, 33 experimental lines and one commercial variety were tested in the preliminary trials at each location.

Grain yield in the advanced tests averaged 10,330 pounds/acre at RES, 9,830 pounds/acre at Sutter, 10,120 pounds/acre at Yolo, and 8,900 pounds/acre at San Joaquin.  Over all locations, the highest-yielding entry on average was an advanced long grain, 06-Y-575 (10,600 pounds/acre), followed by advanced medium grain 05-Y-724 and S-102 (10,460 pounds/acre and 10,190 pounds/acre, respectively). Top-yielding commercial varieties included M-206, M-104, L-206, M-104 and CM-101. 

Averaged across locations, yields in the preliminary tests ranged from 8,530 pounds/acre to 10,130 pounds/acre.

Days to 50 percent heading for most varieties in 2008 was one day more than in 2007. Moderate daytime and cooler nighttime temperatures were responsible for increasing the number of days to heading.

Over a five-year period and across locations, S-102 continues to be the highest yielding very early variety, followed by M-206 at 9,528 pounds/acre and 9,341 pounds/acre, respectively.

Early tests

Ten advanced lines and eight commercial varieties were compared in four early tests.  Preliminary tests included four commercial varieties and 32 preliminary lines evaluated in separate tests at each location.

Yields in the advanced lines averaged 10,530 pounds/acre at RES, 8,200 pounds/acre at Butte, 10,220 pounds/acre at Yuba, and 9,690 pounds/acre at Colusa. Advanced medium grain 05-Y-724 was the highest-yielding entry (10,310 pounds/acre) averaged over four locations in 2008. Other consistently high-yielding entries included 06-Y-575,
07-Y-752, L-206, M-206 and 06-Y-613, all within the top 10 at three out of four locations.

Days to 50 percent heading ranged from 89 days at RES to 93 days at the Colusa County test site.  M-202 headed at 92 days at RES and 96 days at Colusa.

 Over a five-year period and across locations, M-205 continues to be the highest yielding commercial variety at 9,345 pounds/acre, followed by M-206 at 9,029 pounds/acre.

Intermediate-to-late tests

Eight advanced lines and five commercial varieties were compared in three intermediate-to-late tests.  Preliminary tests included four commercial varieties and 18 preliminary lines evaluated in separate tests at each location.

Yields in the advanced lines averaged 10,400 pounds/acre at RES, 8,370 pounds/acre at Glenn and 8,540 pounds/acre at Sutter. The 2008 advanced over-location yield was 430 pounds/acre less than in 2007. Compared to 2007, average yield was up 900 pounds at RES, down 900 pounds at Glenn, and down 1,000 pounds at Sutter. The normally high-yielding Sutter trial was adversely affected by deep water following levee failures. 

M-205 was the highest-yielding commercial variety at 9,270 pounds/acre, fourth over all. M-202 and L-206 were the next highest-yielding commercial varieties across locations. The waxy short grain entry 05-Y-343 was the highest-yielding advanced entry at 9,870 pounds/acre.

Days to 50 percent heading ranged from 93 days at RES to 96 days at the Glenn County location. As in the previous three years, M-402 took the longest time to reach maturity among the commercial varieties (average is 108 days).

Over a five-year period and across locations, M-205 continues to be the highest-yielding commercial variety in this group at 9,438 pounds/acre. M-205 and M-402 produced 105 percent and 96 percent, respectively, of the M-202 yield on average over the last five years.

Stand establishment trial

A long-term stand establishment trial at the Rice Experiment Station continued for a fifth year in 2008.  The purpose of this study is to investigate the influence of different stand establishment methods on rice seedlings, weed germination and recruitment, and nitrogen use efficiency.

The five systems include conventional water seeded; conventional drill seeded; spring-tilled, delayed water seeding; no spring-till water seeding; and no spring-till drill seeding.  The two no-till treatments and the spring-tilled treatment were pre-flush irrigated and treated with Roundup. (Weeds were treated as necessary in the main plot areas, but one area is untreated to evaluate weed germination and recruitment.)

In 2008, these treatments were rotated to determine the impact of various stand-establishment options in rice-only rotational systems. No significant yield differences were reported. The critical issue for this experiment is how each treatment affected weed control in the untreated weedy section of each plot. More detail is contained in other sections of this report.

Rice growth and development

A rice growth and development study begun in commercial fields at the southern and northern ends of the Sacramento Valley continued for a fourth year. An additional site was added in Yolo County in 2006. One short grain, CM-101, and three medium grain Calrose cultivars M-104, M-202 and M-206 were direct seeded in continuous flood at all three locations. The three sites were planted with the same varieties in 2007. The Glenn County site was planted nine and 14 days earlier than the Sutter and Yolo sites. Water and air temperatures were recorded at all sites from planting through grain maturity. Leaf and reproductive stage were also recorded. An analysis of the data collected is continuing.


Home.gif (3162 bytes)Next.gif (3180 bytes)Back.gif (3162 bytes)