Twenty-one experimental lines and four commercial varieties of short- and medium-grain rices also were tested. These tests speed the evaluation and identification of superior lines for future statewide evaluation trials.

Very Early Tests Produce Short-Grain Candidate

Calmochi-101 and M-102 performed the best among the commercial standards used in the trials, with yields of 9,840 and 9,700 pounds per acre, respectively. M-202 and M-101 were significantly lower, with respective yields of 8,960 and 8,570 pounds per acre. A leading short-grain line, 85-Y-136 (recently named S-101), yielded 9,220 pounds per acre. Top yields in the trial were produced by another short-grain line, 86-Y-126, which produced 10,140 pounds per acre.

Early Varieties Affected by Cold

The commercial varieties M-102 and M-202, with respective yields of 9,800 and 9,450 pounds per acre, were the best performers among the commercial varieties included in a five-location trial that involved the rice Experiment Station at Biggs and four off-station locations. M-201, with 7,870 pounds per acre was significantly lower in yield than any of the commercial varieties, which also included S-201, M-101 and L-202. M-201 probably was affected by cold-induced sterility which was a characteristic of the 1987 growing season. The experimental line 86-Y-329 had the highest yields with 10,010 pounds per acre.

At the four off-station sites, Calmochi-101, with a yield of 10,330 pounds per acre, was significantly higher than all other entries, probably because of its superior resistance to cold-induced sterility.

Late Varieties Get Earlier

Many of the experimental lines in this group were intermediate in maturity rather than late, continuing a trend towards earliness. M7, with 111 days to flowering, was the latest variety tested.

M-401, with a yield of 8,880 pounds per acre, was the leading commercial variety tested and ranked third among all entries. The experimental line 86-Y-564 was first with yields of 9,090 pounds per acre. M-302 with 7,960 pounds per acre and M7 with 7,670 pounds per acre ranked 17th and 21st, respectively, but the differences between the two were not statistically significant. A-301, an aromatic long-grain variety targeted for specialty markets, ranked last with 5,810 pounds per acre. Its poorer performance relative to the other varieties and lines tested is due primarily to poor seedling vigor and low resistance to cold-induced sterility.

Water Management Affects Weeds*

A three-year summary suggests that, in the absence of herbicides,  increasing water depth reduces weed competition from watergrass and increases yields, but does not achieve control or yield levels of similar plots treated with herbicide.

In shallow-water and drained basins, weeds flourished and species success depended on competitive ability. Shallow-water plots containing a mixed stand of common rice weeds in 1985 ended up with a solid stand of barnyardgrass in 1987. The only significant weed in the deep-water plots in 1987 was roughseed bulrush. Yield and weed control results in moderate-depth plots were between those of the shallow-water and deep-water plots.

In the absence of intense weed pressure, herbicides worked effectively for all water treatment management strategies, and average yields over the three years did not differ in the herbicide-treated plots.

Another experiment in conjunction with the water management trials compared eight rice varieties, three seeding rates, and three continuous water depths of two, five, and eight inches. Although yields for any given variety were not significantly affected by water treatment or seeding rate, there was a trend to lower yields as water became deeper.

There was a clear difference among varieties in their tolerance to water depth. M-202 performed best at all depths; A-301 the poorest. In shallow water, seeding rate had no effect on yield. At the medium water depth, several varieties indicated a trend to higher yields at higher seeding rates, although A-301 was the only variety that was significantly affected. In deep water, M-201, L-202, Calmochi-101, and A-301 all produced higher yields at higher seeding rates.

Mosquito Larvacide Has No Effect on Rice

A trial to determine if the mosquito larvacide Bti (Bacillus thuringensis) has any adverse effect on rice production suggests that the material, used extensively for mosquito control, does not harm rice. None of the treatments, applied to M-201 in various stages of heading, had a significant effect on plant height, moisture content of harvested grain, or grain yield.

 

Hill Sees "Excellent" Progress One of the oldest projects in the arsenal of research the growers fund to improve the rice industry is the ongoing investigation into variety adaptation and cultural practices. Project leader and UC Cooperative Extension agonomist Jim Hill says the roots of this project can be traced back to the 1940s, prior to the time it received funding from CCRRF Among the many projects UC Davis Cooperative Extension agronomist Jim Hill is involved with is development of new rice varieties. But the keen interest in this area shouldn't be much of a surprise, since how well a given variety performs in the field determines, ultimately, how well the bank account looks at year's end. The objectives of this project are to evaluate experimental cultivars statewide, to link growers directly to research through county farm advisors and to maintain an equipment pool for field testing. Hill says the research team has made "excellent" progress this last year, noting the release of two new varieties and the pending release of two more. Evaluating how well varieties perform under a variety of environmental conditions and cultural practices yields perhaps the most significant information, the researcher believes. Altogether, Hill's research team investigates 40 experimental plots statewide, examining variables such as fertilization, water management, insect control, weather, and field design.