Objective

Evaluation of new cultural, harvesting, and processing practices to achieve maximum production efficiency and grain quality while minimizing management problems, costs, and energy requirements.

Management of short-stature varieties:

As the new short-stature varieties are developed, research on their response to fertilization is necessary to see whether recommendations developed for the taller varieties are still valid. It is being discovered that, based on yield differences, nitrogen fertilizer is utilized more efficiently by the short-stature varieties, and they usually require slightly higher nitrogen rates than their taller counterparts for maximum yield. The short-stature varieties yielded approximately 1,000 pounds per acre greater than tall varieties in 1978 experiments.

This year's experiments with M-101 and M7 indicate that these varieties respond similarly to preplant applications of nitrogen. For M-101, grain yields increased as nitrogen rates increased up to 120 pounds per acre. Additional increments of nitrogen had little effect on yields. Split applications, with two-thirds of the nitrogen applied before planting and one-third at the panicle initiation stage provided yields similar to those achieved from a single preplant application when near optimum rates were used. ,

For M9, the optimum nitrogen rate appeared to be between 90 and 120 pounds per acre when applied before planting. Yields of M9 were increased significantly above those of preplant treatments by split applications when excessive nitrogen was applied.

 

Nitrogen fertilization experiments such as this one showed that a single preplant application of the total nitrogen applied during the season was more efficient than split application of two-thirds preplant and one-third topdressed when near optimum nitrogen rates were used on both short-stature (M9) and tall (Calrose) varieties. The lodged plots in this experiment are the variety Calrose fertilized with 90 to 180 pounds of nitrogen. M7 did not lodge in this experiment.

Response of M7 to different nitrogen rates was similar to that of M-101, with the optimum preplant rate usually being between 90 and 120 pounds per acre. A split application at excessive nitrogen rates did not provide the yield increase observed with M9.

Effect of water level on performance:

Two years of studying the effect of stabilized, continuous water depths on the performance of tall and short-stature varieties indicate that a water depth of six to 10 inches does not greatly alter the yield potential of short-stature varieties in warm environments. The yield potential of the more temperature sensitive M9, however, may be decreased by a continuous six- to 10-inch water depth in cool environments because the water reduces seedling vigor and tillering capacity.

A water depth of six to 10 inches hastened the maturity of S6, M9, M-101, and an experimental short-stature S6 when compared to a continuous water depth of two to four inches. Deep water delayed the maturity, however, of Calrose 76, Calrose, M7 and CS-M3. The shortstature varieties produced approximately 1,000 pounds per acre greater than their tall counterparts in these experiments.

Effect of seeding rate on performance:

Six seeding rate experiments in 1978 indicated that seeding rates greater than 125 to 175 pounds per acre are not required for optimum performance of Calrose 76, M7, M-101, and M9. Seeding rates greater than 175 pounds per acre tended to decrease grain yields of both the tall and short-stature varieties in some locations. The yield reduction caused by seeding rates greater than 175 pounds per acre was probably caused by more severe stem rot disease in these denser stands.

 

A continuous water depth of 6 to 10 inches (right basin with open water) reduced seedling vigor and number of panicles/m2 of both tall and short varieties compared to a shallow depth of 2 to 4 inches at Biggs. The deep water, however, did not reduce grain yields of the short-stature Calrose 76, M7, M9 and M-101 or tall Calrose, CS-M3 and S6"varieties in this warm location.

Evaluation of new varieties for harvestability:

Harvestability tests concentrated primarily on the varieties M9 and M7. The variety M7 appears to be suitable for normal harvester setups, but M9 may require special adjustments (i.e., more concave teeth and/or less concave clearance) because of difficulty of thrashing. Growers in 1978, however, reported few harvest problems with M9. Substantial lodging of M-9 in the test fields in 1978 also reduced its harvestability. Field drainage too early appeared to partially cause the M9 lodging.

New drying systems:

A computer aided simulation of a cross-flow rice drier has been developed and tested in the laboratory. The results are promising. With future refinement, this computer model should provide an easy tool for the rice drier operator to select operating variables for reduced energy consumption and better quality.

"The yield reduction caused by seeding rates greater than 175 pounds per acre was probably caused by more severe stem rot disease in these denser stands."

Effect of seed coating on performance:

The agronomic effects of seeding coating should be studied further before soaking operations are replaced. Two experiments to determine the effect of seed coating on the performance of M9, Calrose 76 and M7 indicate that coating of the seed slightly delayed seedling emergence and development but did not significantly affect grain yields. Additional testing will be necessary to ascdrtain whether seed coating can be used in place of water soaking of seed. Elimination of the soaking process in seed handling operations could greatly improve efficiency.