Several variety trials produced average yields of 10,000 pounds per acre. Some experimental and commercial cultivars produced more than 12,000 pounds per acre.

The following narrative summarizes variety trial research - and related nitrogen and weed control studies - in more detail.

Eleven advanced breeding lines and 11 commercial cultivars were compared in four very early tests (less than 90 days to 50 percent heading). Sixteen breeding lines were also evaluated at each location.

Yields in the advanced tests were high, averaging 11,600 pounds/acre at Sutter, 9,500 pounds/acre at Biggs, 9,400 pounds/ acre at San Joaquin and 7,800 pounds/ acre at Butte.

Over all locations, the highest yielding entry in the advanced test was an early maturing, medium grain proposed for release as M-204. It yielded more than 10,300 pounds/ acre.

One short grain among the preliminary lines, 89-Y-103, yielded a remarkable 13,000 pounds at Suffer and was the highest-yielding entry in the four location summary.

Some experimental and commercial cultivars produced more than 12,000 pounds per acre in last year's trials.

 

Twelve advanced breeding lines and 10 commercial cultivars were compared in five early tests (90-97 days to 50 percent heading). Sixteen preliminary lines were also evaluated at each location.

Grain yields in the advanced tests averaged 10,940 pounds/acre at Yolo,10,130 pounds/acre at Yuba, 9,180 pounds/acre at Colusa and 9,130 pounds/acre at Biggs. As in the very early tests, entry 88-Y-317 ranked first in yield, averaging, 10,700 pounds/acre over the four locations.

Of the preliminary lines, the medium grain 90-Y-210 was the highest yielding entry, averaging 10,400 pounds over all locations.

Six commercial cultivars and 12 advanced breeding lines were compared in three intermediate-late tests (more than 97 days to 50 percent heading). Twelve preliminary breeding lines were also evaluated at each location.

Average yields in the advanced line tests were 8,390 pounds/acre at Suffer, 9,560 pounds/acre at Biggs, and 11,460 pounds/acre at Glenn. Over all locations, the medium grain 88-Y-271 produced the highest yield at 10,710 pounds/acre.

In the Glenn County trial, M-201 yielded 12,910 pounds/acre, a record yield in Cooperative Extension four-replication rice variety trials.

At the Rice Experiment Station in Biggs, researchers also conducted two experiments to examine fertilization rates for several commercial cultivars and the advanced breeding line, 88-Y-317.

Generally, average yields increased with greater nitrogen levels. Most cultivars produced their highest yields at 150 pounds/acre, but yields tended to decline at 180 pounds/acre. In the advanced line, yields were significantly reduced at the higher rate.

Higher nitrogen levels also displayed a tendency to delay heading dates, increase grain moisture, and increase plant height and lodging.

Perhaps not surprisingly, the Japanese variety Akitakomachi, which has proven extremely sensitive to lodging under typical water-seeded conditions in California, produced its highest yield with no applied nitrogen and did not respond to increased nitrogen fertility in this experiment.

Researchers also wrapped up a three-year study of how water depth affects rice growth, weed control and herbicide effectiveness. Their findings show that growers can raise rice in "deep water" (i.e. 7-8 inches) with little or no loss in yield.

Deep water can improve grass control and, under certain circumstances, grass herbicides can be eliminated without sacrificing weed control. In fact, the researchers found that grass control was better with deep water alone than with shallow water and a grass herbicide, which may be due to the limited activity of Londax® (used in the experiments) on grasses.

These water management studies also showed that early season rice growth and stand establishment are slowed by deep water. Although the delay usually disappears by mid- to late season, early season growth differences could become more significant should they interact with pests, abiotic disorders or poor weather adversely affecting the crop.