Varietal Testing and
Cultural Practices-85
 
 

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Project Leader and Principal UC Investigators

J.E. Hill, S.C. Scardaci, C.M.Wick, J.F. Williams, D.E. Snell, C.M. Canevari, M. Feyler, B.L. Weir, and L.A. Post,  UC Cooperative Extension

 

Objective

Experimental varieties of rice are tested at different locations to determine if their performance warrants their increase, certification and release. Various cultural practices are compared with those of existing varieties. Professional assistance and equipment is made available as needed to other research workers with the University of California or U.S. Department of Agriculture.

Statewide Uniform Rice Variety Trials

Nine variety trials were conducted in counties and four were conducted at the Rice Experimeht Station. The varieties were tested by maturity groups - very early, early, and late. Very early varieties reach 50 percent heading in less than 90 days after planting. Early varieties head in 90 to 97 days, intermediate varieties in 98-105 days and late varieties require more than 105 days. Intermediate and late varieties were tested together. A special long-grain trial was conducted in Yolo County.

New varieties are not certified and released until they are tested for at least two years in statewide trials.

Very early variety trials with 22 common, entries were completed in Sutter County and at the Rice Experiment Station. The leading experimental variety was a short grain (83-Y-14) that produced 10,410 lbs/acre. A medium grain experimental (84-Y-149) under consideration as a replacement for M-101 ranked seventh and was significantly higher in yield than M-101 but was six days later in heading.

Early variety trials in five locations with 26 entries in each included the commercial varieties M-202, M-201, L202, M-101 and California Belle. Several additional varieties were included in four county trials. M-202 was the leading variety for yield and has ranked at or near the top for this maturity group for four consecutive years. M201 also has ranked consistently high in yield over the years. The very early experimental 84-Y149 also was tested in the early maturity trials to assess its performance over a wider range of environments since it is being considered as a replacement for M-101. It ranked second overall in these tests and yielded significantly more than M-101 but headed five days later.

Late variety trials with 25 varieties were compared in three locations. The commercial standards were M-302, M-7 and M-401. An experimental medium grain variety, 80-Y-393, was the top in grain yield at 10,200 lbs/acre. In these trials, there were several experimental short and medium grain varieties that exceeded the yields of the three commercial standards.

Long grain trials were conducted in two locations. Three of the experimental varieties yielded significantly higher than L-202, but all were new entries in county trials and require additional testing before being considered for release to rice growers.

Cultural Practices

The technique of drill seeding rice with minimum or no previous tillage was developed in Australia and has been gaining interest in California since 1982. In 1985 approximately 2,500 acres were drill seeded. Drill seeding and conventional water seeding were compared for three early maturing varieties. Results will be reported when analysis is completed.

Seeding rate studies in 1984 showed no significant differences in yields from seeding rates of 90, 150, and 210 Ibs/acre. These results confirm those previously reported. '

Five varieties were compared at four locations in 1984 with 0, 50, 100, 150 and 200 lbs/acre of nitrogen. Maximum yields of M-201, M-9, Calpearl, and California Belle were obtained with 100 lbs/acre. L-202 produced maximum yields with 150 lbs/acre. Over fertilization was most injurious to M-9 and California Belle.

Water Management-Colusa County
(Funded by the State Water Resources Control Board)

The objective of this study was to evaluate the effect of rice water management practices on molinate residues, rice pests and rice production. Water depth comparisons confirmed earlier studies showing better weed control with deep water (6 to 7 inches) than shallow water (2 to 3 inches). Slightly fewer plants emerged from deep water, but stands were adequate and results clearly indicated that short statured varieties have greater capability for emerging through deep water than previously realized.

Draining rice field water for 10 days reduced rice growth and tiller production after reflooding. Also, drainage allowed growth of roughseed bulrush, ducksalad and waterhyssop. Drainage also stimulated regrowth and a second germination of watergrass.

Water holding periods of 16 or 32 days following a postflood application of Ordram had little, if any, effect on either rice or weed growth when compared to an 8-day water holding period. Preflood Ordram applications and incorporation provided fairly effective control of roughseed bulrush and watergrass, but watergrass control was not complete and may require a postflood application of Ordram or Bolero. The preflood and incorporated Ordram applications reduced residues in drainage water.

Water Management - Sutter County
(Funded by the University of California Integrated Pest Management Project)

Preliminary results confirmed that a continuous water depth of 5 to 8 inches combined with use of herbicides provided better weed control than either deep water or pesticides alone. Shallow water or drainage after seeding gave inadequate weed control without the use of herbicides.

Project Leaders: J.E. Hill, S.C. Scardaci, C.M. Wick, J.F. Williams, D.E. Snell, C.M. Canevari, M. Feyler, B.L. Weir, and L.A. Post, Cooperative Extension, University of California.

 

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