Variety Trials 06

Variety Trials - 2006
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 2006 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 8,620 pounds/acre in the very early trials to about 9,040 pounds/acre in the early tests. In the intermediate to late test, the advanced lines yielded more than 8,170 pounds/acre. Similar to the exceptionally wet 2003 planting season, the 2006 season resulted in reduced planted acreage and lower average yields. A two-week period of temperatures over 100 degrees Fahrenheit helped shorten the days to harvest but may have negatively affected yield. Nonetheless, statewide yields in 2006 averaged 7,660 pounds/acre on 523,000 planted acres, according to USDA statistics. Several advanced lines in 2006 produced high yields and showed improvement toward other 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. In addition to variety studies, a long-term rice cropping systems experiment on stand establishment continued for a third year at the Rice Experiment Station. Five different methods of stand establishment are being evaluated for their impact on weed management. This work is described in more detail below. Very Early Tests Seven advanced breeding lines and 10 commercial varieties were compared in four very early advanced tests. Additionally, 34 cultivar lines were tested in the preliminary trials at each location. Grain yield in the advanced tests averaged 9,020 pounds/acre at RES, 8,530 pounds/acre at Sutter and 8,310 pounds/acre at Yolo. Over all locations, the highest-yielding entry on average was S-102 (9,230 pounds/acre), followed by the advanced line 04-Y-508 (9,150 pounds/acre), L-206 (9,100 pounds/acre) and advanced Newrex grain type 01-Y-655 (8,980 pounds/acre). Top-yielding commercial varieties included M-206, M-202, L-205 and M-104. Days to 50 percent heading for most varieties in 2006 were two to six days fewer than in 2005. A significant percentage of the rice acreage was planted later than normal due to frequent spring rains that delayed field preparation. Lodging scores across all locations were similar to 2004 and 2005. Over a five-year period and across locations, S-102 continues to be the highest yielding very early variety, followed by M-206 at 9,456 pounds/acre and 9,185 pounds/acre, respectively. Early Tests Ten advanced lines and 10 commercial varieties were compared in four early tests. Preliminary tests included two commercial varieties and 28 preliminary lines evaluated in separate tests at each location. Yields in the advanced lines averaged 9,370 pounds/acre at RES, 8,370 pounds/acre at Butte, and 9,390 pounds/acre at Colusa. The advanced stem rot-resistant long grain 03-Y-496 was the highest-yielding entry (10,090 pounds/acre) averaged over three locations in 2006. Other consistently high-yielding entries included 04-Y-404, 99-Y-529, 03-Y-151, M-205, L-206, and M-208. Days to 50 percent heading ranged from 77 days at the Yuba County test to 89 days at the Colusa County site. Commercial standard M-202 headed at 81 days at RES and 85 days at Colusa. Days to 50 percent heading was similar to 2005. Over a five-year period and across locations, M-205 continues to be the highest yielding commercial variety at 9,551 pounds/acre, followed by M-206 at 9,050 pounds/acre. Intermediate-to-Late Tests Eight advanced lines and six commercial varieties were compared in three intermediate-to-late tests. Preliminary tests included two commercial varieties and 18 preliminary lines evaluated in separate tests at each location. Yields in the advanced lines averaged 9,030 pounds/acre at RES, 6,970 pounds/acre at Glenn and 8,510 pounds/acre at Sutter. The over-location average yield was 490 pounds/acre less than in 2005. L-206, the highest yielding commercial variety, ranked sixth overall (9,210 pounds/acre at RES). L-205 and M-205 were the next highest yielding commercial varieties across locations. The stem rot-resistant short grain entry 04-Y-641 was the highest-yielding advanced entry across locations at 8,740 pounds/acre. Days to 50 percent heading ranged from 80 days at the Sutter County site to 82 days at the Glenn County and RES locations. The number of days to 50 percent heading was about four to six days fewer than in 2005. M-402 took the longest time to reach maturity among the commercial varieties (102 days). Over a five-year period and across locations, M-205 continues to be the highest-yielding commercial variety in this group at 9,582 pounds/acre. M-205 and M-402 produced 107 percent and 98 percent, respectively, of the M-202 yield on average over the last five years. Cultural Practices A long-term stand establishment trial at the Rice Experiment Station continued for a third year in 2006. The purpose of this study is to investigate the influence of different stand establishment methods on rice seedlings, weed resistance and nitrogen use efficiency. The five systems included 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 treated with Roundup® to remove germinated weeds prior to planting. Weed control in the no-till, water-seeded treatment was greatly reduced. Weeds were treated as necessary in the main plot areas, but one area remained untreated to evaluate weed germination and recruitment. Various nitrogen rates and application timing were tested among stand establishment methods. In the conventional water seeded and delayed spring-tilled stale seedbed treatments, where the soil is spring tilled, nitrogen was incorporated preplant. In the drill-seeded stand, nitrogen was applied in splits. In the no spring-till drilled and water-seeded treatments, where soil disturbance would defeat the purpose of non-tillage with respect to weed recruitment, nitrogen was also applied in splits. Phosphorous was applied to the entire block and incorporated where spring tillage occurred. In future applications, phosphorous will be applied to the whole block and incorporated with fall tillage. Yield data for the first three years of the study show no significant yield differences among treatments, but there were definite trends worth noting. Lower yields in the spring tilled, delayed seedbed water seeding was attributed to the fact that water was lowered after preplant nitrogen was applied. Significant nitrogen loss occurred in the 10-14 days of drainage needed to encourage weed growth and treat with Roundup®. When nitrogen was applied at a rate of 200 pounds/acre in this treatment, however, yields increased to the level of other treatments. This clearly illustrates the impact of draining fields in respect to nitrogen losses. More detail on stand establishment studies is reported in the Weed Control in Rice section of this annual report. A rice growth and development study begun in commercial fields at the southern and northern ends of the Sacramento Valley continued for a second year with the addition of a new site in Yolo County. One short grain, CM-101 and three medium grain Calrose cultivars – M-104, M-202, and M-206 – were grown at all three locations. The Glenn County site also included M-401. Plots were direct seeded by hand into a continuously flooded environment. Detailed information collected on leaf and reproductive stage development is being analyzed.

Variety Trials - 2006

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 2006 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 8,620 pounds/acre in the very early trials to about 9,040 pounds/acre in the early tests. In the intermediate to late test, the advanced lines yielded more than 8,170 pounds/acre.

Similar to the exceptionally wet 2003 planting season, the 2006 season resulted in reduced planted acreage and lower average yields. A two-week period of temperatures over 100 degrees Fahrenheit helped shorten the days to harvest but may have negatively affected yield. Nonetheless, statewide yields in 2006 averaged 7,660 pounds/acre on 523,000 planted acres, according to USDA statistics.

Several advanced lines in 2006 produced high yields and showed improvement toward other 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.

In addition to variety studies, a long-term rice cropping systems experiment on stand establishment continued for a third year at the Rice Experiment Station. Five different methods of stand establishment are being evaluated for their impact on weed management. This work is described in more detail below.

Very Early Tests

Seven advanced breeding lines and 10 commercial varieties were compared in four very early advanced tests. Additionally, 34 cultivar lines were tested in the preliminary trials at each location.

Grain yield in the advanced tests averaged 9,020 pounds/acre at RES, 8,530 pounds/acre at Sutter and 8,310 pounds/acre at Yolo. Over all locations, the highest-yielding entry on average was S-102 (9,230 pounds/acre), followed by the advanced line 04-Y-508 (9,150 pounds/acre), L-206 (9,100 pounds/acre) and advanced Newrex grain type 01-Y-655 (8,980 pounds/acre). Top-yielding commercial varieties included M-206, M-202, L-205 and M-104.

Days to 50 percent heading for most varieties in 2006 were two to six days fewer than in 2005. A significant percentage of the rice acreage was planted later than normal due to frequent spring rains that delayed field preparation. Lodging scores across all locations were similar to 2004 and 2005.

Over a five-year period and across locations, S-102 continues to be the highest yielding very early variety, followed by M-206 at 9,456 pounds/acre and 9,185 pounds/acre, respectively.

Early Tests

Ten advanced lines and 10 commercial varieties were compared in four early tests. Preliminary tests included two commercial varieties and 28 preliminary lines evaluated in separate tests at each location.

Yields in the advanced lines averaged 9,370 pounds/acre at RES, 8,370 pounds/acre at Butte, and 9,390 pounds/acre at Colusa. The advanced stem rot-resistant long grain 03-Y-496 was the highest-yielding entry (10,090 pounds/acre) averaged over three locations in 2006. Other consistently high-yielding entries included 04-Y-404, 99-Y-529, 03-Y-151, M-205, L-206, and M-208.

Days to 50 percent heading ranged from 77 days at the Yuba County test to 89 days at the Colusa County site. Commercial standard M-202 headed at 81 days at RES and 85 days at Colusa. Days to 50 percent heading was similar to 2005.

Over a five-year period and across locations, M-205 continues to be the highest yielding commercial variety at 9,551 pounds/acre, followed by M-206 at 9,050 pounds/acre.

Intermediate-to-Late Tests

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

Yields in the advanced lines averaged 9,030 pounds/acre at RES, 6,970 pounds/acre at Glenn and 8,510 pounds/acre at Sutter. The over-location average yield was 490 pounds/acre less than in 2005. L-206, the highest yielding commercial variety, ranked sixth overall (9,210 pounds/acre at RES). L-205 and M-205 were the next highest yielding commercial varieties across locations. The stem rot-resistant short grain entry 04-Y-641 was the highest-yielding advanced entry across locations at 8,740 pounds/acre.

Days to 50 percent heading ranged from 80 days at the Sutter County site to 82 days at the Glenn County and RES locations. The number of days to 50 percent heading was about four to six days fewer than in 2005. M-402 took the longest time to reach maturity among the commercial varieties (102 days).

Over a five-year period and across locations, M-205 continues to be the highest-yielding commercial variety in this group at 9,582 pounds/acre. M-205 and M-402 produced 107 percent and 98 percent, respectively, of the M-202 yield on average over the last five years.

Cultural Practices

A long-term stand establishment trial at the Rice Experiment Station continued for a third year in 2006. The purpose of this study is to investigate the influence of different stand establishment methods on rice seedlings, weed resistance and nitrogen use efficiency.

The five systems included 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 treated with Roundup® to remove germinated weeds prior to planting. Weed control in the no-till, water-seeded treatment was greatly reduced. Weeds were treated as necessary in the main plot areas, but one area remained untreated to evaluate weed germination and recruitment.

Various nitrogen rates and application timing were tested among stand establishment methods. In the conventional water seeded and delayed spring-tilled stale seedbed treatments, where the soil is spring tilled, nitrogen was incorporated preplant. In the drill-seeded stand, nitrogen was applied in splits. In the no spring-till drilled and water-seeded treatments, where soil disturbance would defeat the purpose of non-tillage with respect to weed recruitment, nitrogen was also applied in splits.

Phosphorous was applied to the entire block and incorporated where spring tillage occurred. In future applications, phosphorous will be applied to the whole block and incorporated with fall tillage.

Yield data for the first three years of the study show no significant yield differences among treatments, but there were definite trends worth noting. Lower yields in the spring tilled, delayed seedbed water seeding was attributed to the fact that water was lowered after preplant nitrogen was applied. Significant nitrogen loss occurred in the 10-14 days of drainage needed to encourage weed growth and treat with Roundup®. When nitrogen was applied at a rate of 200 pounds/acre in this treatment, however, yields increased to the level of other treatments. This clearly illustrates the impact of draining fields in respect to nitrogen losses. More detail on stand establishment studies is reported in the Weed Control in Rice section of this annual report.

A rice growth and development study begun in commercial fields at the southern and northern ends of the Sacramento Valley continued for a second year with the addition of a new site in Yolo County. One short grain, CM-101 and three medium grain Calrose cultivars – M-104, M-202, and M-206 – were grown at all three locations. The Glenn County site also included M-401. Plots were direct seeded by hand into a continuously flooded environment. Detailed information collected on leaf and reproductive stage development is being analyzed.