Variety Trials-04



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Project Leader and Principal UC Investigators

James E. Hill, UCCE Specialist, Dept. of Agronomy and Range Science, UC Davis


Sixteen on-farm rice variety evaluation trials were conducted throughout the rice-growing regions of California in 2004 by UC Cooperative Extension in collaboration with public and private plant breeders.  These trials perform an essential role in exposing standard, advanced and preliminary varieties to a range of environments, cultural 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 10,120 pounds/acre in the very early trials to about 9,990 pounds/acre in the early tests.  Unlike the exceptionally wet 2003 planting season, the 2004 season was dry and provided excellent conditions for field preparation.  Stands were nearly ideal and the remainder of the season was also exceptional for rice, resulting in record statewide yields of 8,800 pounds/acre on nearly record plantings of approximately 600,000 acres.  Several advanced lines in 2004 produced very high yields.

This project also conducted experiments on nitrogen fertility to improve use of the leaf color chart, as well as others experiments geared toward management of blast and Bakanae diseases.  Details of this work are summarized below.

Very early tests

Ten advanced breeding lines and eight commercial varieties were compared in four very early advanced tests.  Additionally, 32 cultivar lines were tested in the preliminary trials at each location.

Grain yield in the advanced tests averaged 9,420 pounds/acres at the RES, 8,560 pounds/acre at San Joaquin, 10,540 pounds/acre at Sutter and 9,340 pounds/acre at Yolo.  Over the three locations (Yolo excluded because of herbicide damage), the highest yielding entry on average was the long grain L-204 at 10,120 pounds/acre, followed by the advanced long grain 99-Y-469 (10,010 pounds/acre), medium grain M-206 (9,820 pounds/acre) and 02-Y-210, a waxy short grain (9,740 pounds/acre).  Other top-yielding commercial varieties included S-102, L-205, M-202 and M-104.

Time to 50 percent heading for most varieties in 2004 was 10 to 12 days longer than in 2003, the increase attributed to relatively mild summer temperatures and earlier plantings.  Lodging scores across all locations were similar to 2003.

Over a five-year period and across locations, S-102 continues to be the highest yielding variety in the very early test, followed by the early variety M-206.

Early tests

Ten advanced lines and 10 commercial varieties were compared in four early tests.  Thirty-two preliminary lines were also evaluated in separate tests
at each location.

Yields in the advanced lines averaged 9,350 pounds/acre at the RES, 8,750 pounds/acre at Butte, 10,250 pounds/acre at Colusa and 8,720 pounds/acre at Yuba.  The advanced premium quality short grain 01-Y-327 was the highest-yielding entry averaged over the four locations at 9,990 pounds/acre.  Other consistent high yielders included M-205, 99-Y-529, 01-Y-655, 02-Y-382 and M-202.

Days to 50 percent heading ranged from 84 at RES to 90 at Colusa.  As in the very early tests this year, maturity was about 10 to 12 days longer than in 2003.

Over a five-year period and across locations, M-205 was the highest yielding commercial variety at 9,881 pounds/acre, followed by M-204 at 9,460 pounds/acre.

Intermediate to late tests

Eight advanced lines and six commercial varieties were compared in three intermediate-to-late tests. Twenty preliminary lines were also evaluated in separate tests at each location.

Yields in the advanced lines averaged 10,120 pounds/acre at the RES, 9,410 pounds/acre at Glenn and 10,650 pounds/acre at Sutter.  The over-location average increased 1,190 pounds/acre compared to 2003.  Except at Biggs, the yield of M-205 (10,410 pounds/acre) was not significantly different than the leading entry at Glenn and Sutter. L-205 and M-202 were the next highest-yielding commercial varieties across locations; short grain 03-Y-324 was the highest yielding advanced entry (10,820 pounds/acre).

Days to 50 percent heading ranged from 87 at RES to 95 at Glenn, which was three to nine days less than in 2002.  Moderate summer temperatures increased the number of days to heading an average of three to nine days more than in 2003.

Over a five-year period and across locations, M-205 has been the highest yielding commercial variety in this group at 10,179 pounds/acre. M-205 and M-402 produced 108 percent and 98 percent, respectively of the yield of M-202 on average over the last five years.

Cultural practices

Fertility experiments seek to improve nitrogen management.  Field studies continued from 2003 in Butte and Colusa counties.  M-205 and M-202 were grown under a range of nitrogen levels either preplant or split applications.  Tissue nutrient information is being used to fine-tune the leaf color chart and to optimize yield in relation to nitrogen, phosphorus and potassium levels.  Low amylose lines under development for the Japanese market are also being analyzed to determine variety-specific nitrogen recommendations for optimal yield.

Several studies were aimed at disease management.  Blast-resistant line 00-Y-805 (to become M-207) was tested against M-202 and M-206.  Seed treatments an Ultra Clorox soak for Bakanae disease were also evaluated.  Most of these treatments significantly reduced the incidence of Bakanae in M-205 from 18 percent to 2 percent or less.  Yields were 10 percent higher than in untreated seed.

A long-term project was begun at RES to investigate the influence of different stand establishment methods on weed resistance management.  The methods include conventional water seeded; conventional drill seeded; spring tilled, delayed water seeding; no spring till, water seeding; and no spring till, drill seeded.  Since these stand establishment methods require different water management practices, a better understanding of how nitrogen use efficiency will be affected is needed.


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