Objective

Development of basic knowledge needed to support and expedite production research projects.

Genetic manipulations for improved yield and quality

Studies of carbohydrate (starch) distribution during grain filling indicate that the plant has more capacity to produce than to store starch in the panicle. This supports the idea that larger panicles could improve yields. In other research, an early mutant from Calrose 76 that heads in 96 days produced significantly greater yields and less straw than Calrose 76.

Heritability studies to identify genes that will increase grain size and number are in progress. We now know there is wide variability among varieties and selections for low-temperature-induced sterility and that it is influenced by earliness of maturity, short stature, water depth, and genetics. Genetic control of low-temperature-induced sterility is being investigated in crosses among 10 parent varieties. Additional genetic studies are in progress on amylose content. Also, three independent genes for short stature have been studied, and selections have been made for several very-early-maturing, short-stature, short-grain lines and for a reduced-awn version of Calrose 76.

"The critical levels of nitrogen in leaf tissue of M-101, M7 and M9 were slightly higher than those for the tall varieties, particularly Calrose and Earlirose."

Nitrogen tissue test for new varieties

The relationship between tissue levels of nitrogen at various stages of rice plant development and ultimate yield was refined to include the new short-stature varieties. It was found that the critical levels of nitrogen in leaf tissue of M-101, M7 and M9 were slightly higher than those for the tall varieties, particularly Calrose and Earlirose. This year's experiments suggest that the desirable tissue nitrogen levels for these short-stature varieties should be 4 to 4.5 percent at mid-tillering, 3 to 3.5 percent from maximum tillering through panicle initiation, and 2.4 to 3 percent in the booting and plant growth stages.