Variety Trials - 88



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Project Leader and Principal UC Investigators

Jim Hill, Extension agronomist, Department of Agronomy and Range Science, UC Davis


For growers and researchers alike, the weather produced bad news during 1988.

IN THE BEGINNING-Cane of the first steps in field testing experimental lines is water seeding. Here field crews are wading through experimental plots at the Rice Experiment Station in Biggs. The silos to the southeast of the station belong to the Butte County Rice Growers Association.

Early season cool temperatures and rain led to thin stands, weed competition and delayed heading; late season high temperatures and wind caused severe lodging. Weather was an important factor in results of nine variety trials, involving many experimental and commercial rice cultivars, throughout the state's rice-growing regions.

Two commercial cultivars, M-102 and M-201, were the overall best performers.

Advanced breeding lines

Nine trials for uniform evaluation of advanced breeding lines were conducted in Glenn, Sutter, Yuba, Yolo, Stanislaus and Fresno counties. Four others were located on the Rice Experiment Station at Biggs in Butte County. These variety trials were grouped into: (1) very early maturity, (2) early maturity, (3) intermediate and late maturity and (4) short and medium grain.

Very early maturity. Thirty-two cultivars were tested. M-102 (8,970 pounds/acre) and M-201 (8,780 lb/ac) were the highest yielding commercially available varieties. High yielders among the experimental lines were 87-Y-760 (8,950 lb/ac) and 87-Y-384 (8,850 lb/ac). Lowest ranking were M-203 and M-101, both of which lodged severely. All measurements were at 14 percent moisture.

Early maturity. Twenty experimental lines and 10 commercially available cultivars were tested. Among the highest ranking commercial entries were M-201 (9,130 lb/ac), L-202 (8,930 lb/ac), M-102 (8,790 lb/ac) and Valencia 87 (8,740 lb/ac). The two highest yielding experimental varieties were 87-Y-285 (9,020 lb/ac) and 87-Y-456 (8,880 lb/ac). Again, the lowest ranked were M-101 and M-203, which showed most lodging damage.

Intermediate and late maturity. Four commercially available varieties (A-301, M-7, M-302, M-401) were compared to 20 experimental lines. Several of the latter, led by 87-Y-530 with a yield of 8,390 pounds per acre, came in ahead of the top commercial cultivars, which were M-401 (7,720 lb/ac) and M-7 (7,690 lb/ac). A-301, an aromatic long grain, ranked 17th out of 24, somewhat better than in previous years.

Short and medium grain. These special screening tests to select lines for entry into the statewide trials were conducted in Colusa County and at the Biggs station. Twenty experimental lines and five commercial cultivars were compared. M-202 was the highest ranking commercial cultivar, listed third overall; M-102 and S-101. were intermediate in yield.

Nitrogen trials

Five studies comparing the response of several rice cultivars to nitrogen were conducted in Fresno and San Joaquin counties and at Biggs. Competition from weeds was significant. Among the results:

  • L-202 was fertilized at rates ranging from none to 200 pounds of nitrogen per acre as ammonium sulfate. Highest yields were reached at 150 pounds of nitrogen per acre, substantially higher than in the previous year. There was no lodging.
  • Two very early varieties (M-101 and 84-Y-9) received nitrogen rates ranging from none to 210 pounds per acre. The level of significantly highest yield was reached at about 90 pounds per acre. Again, there was no lodging.

At seven of the experimental sites, daily maximum and minimum temperatures were monitored in the air, the water and the soil. These data will be used to correlate rice growth and development, especially heading date, to local air and water temperatures.

Computerized management

The first step toward development of a rice management computer program came as researchers fed rice data into an "expert system shell" originally developed for cotton in California.

Expert systems are powerful software tools that connect users with virtually everything that's known about a given problem. Rice knowledge bases integrated into the system include:

  • Weed management comprised of general information, weed monitoring and identification, cultural control, and herbicide susceptibility table.
  • Agronomic management involving seeding rates, water management and fertilizer recommendations.
  • Economic analysis based on relationships among milling quality, harvesting moisture and applied nitrogen levels.

The rice expert system is readily expandable.

Researchers also developed a prototype computerized system to automatically measure and record the weight and physical dimensions of large numbers of rice kernels.

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