The experimental lines entered into statewide trials are grouped into the three maturity classes: very early, early and intermediate plus late. The very early tests were conducted in three locations and the other two maturity classes in four locations each.

Very Early Variety Trial

Entries in this trial were those reaching 50 percent heading in 90 days or less at Biggs. One of these trials was located in a cool area (Natomas, Sacramento County) and one in a warmer area (Biggs Rice Experiment Station, Butte County). Thirteen of the experimental lines, all short or medium grain, yielded significantly more than M-101. An experimental short grain type that performed well in two previous years was the top yielder at Biggs and is a possible variety candidate. Calpearl, a proprietary variety, produced significantly higher yields than all other entries at the Sacramento location. The indica or long grain types were severely blanked due to the cool 1982 season which in turn adversely affected yields.

Early Variety Trials

Early varieties are those that reached 50 percent heading between 90 and 99 days from planting at Biggs. M-201 was the top yielder among the 24 public entries in this group as averaged over four locations. The short-grain variety S-201 did not differ significantly from four higher yielding lines, including M-201. Calpearl, a very early proprietary variety included at three of these locations, yielded the highest of all varieties tested.

Long grain varieties produced generally lower yields than the short and medium grain types. Notable exceptions were one experimental entry which ranked fourth and L-201 which ranked seventh. California Belle, a proprietary long grain, exhibited much variability in heading time and was near the bottom in yield. Current long grain varieties are not well adapted to cool areas.

Intermediate to Late Variety Trials

The intermediate and late varieties are those requiring 99 to 104 and more than 105 days, respectively, to reach 50 percent heading at Biggs. The top 14 entries did not differ significantly in yield, and they included M-302 (intermediate maturity) and M7 as check varieties. M-401 was near the bottom in yield and was lodged nearly 100 percent in, all tests except in the Sutter Basin (Juisti) where it lodged 50 percent and ranked 6th in the trial. One long grain variety tested off station for the first time was among the top yielders.

Special Long Grain Variety Trial

Long grain rice production would significantly increase the diversity of rice produced in California. Identical long grain yield trials were conducted in Yolo County and at the Rice Experiment Station. Several experimental long grains yielded at or near the 10,000 pounds per acre yield level of M-201, the test standard. Long grain experimentals will be tested further for yield, cooking characteristics and other quality factors.

Commercial Variety Trials

Three tests of public and proprietary varieties were conducted in Fresno, San Joaquin, and Tulare counties. .Data from the San Joaquin trial were not available when this report was prepared due to late harvest. Calpearl was the leading variety in the other two trials, followed by M-201. The latter showed the greatest resistance to lodging.

Cultural Practice Trials with Farm Advisors

Studies were conducted in Colusa and Glenn counties to determine the relationship between grain and straw production at different nitrogen rates for the tall (S6) and short (S-201) rice varieties. Grain yields of both varieties increased as nitrogen was increased to 150 pounds per acre, but they decreased at nitrogen rates higher than 150 pounds per acre. The proportion of grain to straw decreased with increasing nitrogen rates and 5201 had a higher proportion of grain than S6.

Zinc application methods were compared in 1981 and 1982. The 1981 trial showed that soil applications of zinc as zinc sulfate at rates of 4 to 16 pounds per acre and zinc coated seeds at 2.89 pounds per acre provided sufficient amounts of zinc to correct a deficiency. Zinc treated seeds at 0.1 pound per acre were not sufficient. Zinc coating of seeds delayed seedling growth because the grain was not soaked prior to seeding.

Application of gypsum to an alkaline soil in Colusa County increased rice yields. Ferric sulfate applied at equivalent rates to the gypsum also increased yields, but not significantly, in 1981. Yields in 1982, the second season after the amendments were applied, also were higher than untreated plots, but these differences were not statistically significant.