Japonica rice germplasm resources alkali resistance identification conditions and indicators

Cheng Guangyou et al. studied the height, tiller number and total number of green leaves of rice under different alkali stress intensities, and pointed out that it is more suitable for the alkali tolerance screening of rice varieties under pH 8. 6 alkali stress conditions, and believes that rice seedlings The 4th and 8th weeks after transplanting were the best time for rice alkali tolerance identification. Liang Zhengwei et al. found that the number of rice tiller and heading date are the measures of rice salt-tolerant alkaline traits by comparing phenotypic traits such as plant height, stem number, heading, heading, date of full heading, culm length, and internode length. Better indicators.

The related studies showed that the pH 9·4 alkali stress condition had a greater effect on the dead-leaf rate of Japonica germplasm resources than the pH 8.9 alkali stress condition, but the pH 8·9 alkali stress was more conducive to carry out alkali resistance of japonica rice germplasm resources. Identification screening, which is similar to the results of Cheng Guangyou et al. In 2008, pH 8·9 alkali stress on the 16th to 26th days, in the range of 20% to 100% dead leaf rate, its frequency distribution showed a nearly normal continuous distribution, and its variance and coefficient of variation were large, so it was considered that in 2008 pH8·9 alkali stress was suitable for the alkali-tolerance identification period of indica rice germplasm resources from the 16th to the 26th day, which was the best time for rice alkali tolerance identification after the 4th week after transplanting rice seedlings of Cheng Guangyou et al. The views are somewhat similar. Guo Wangmo et al. showed that the salt-tolerance capacity of the same rice cultivar at the bud and seedling stages was different, and the seeds showed relatively salt tolerance during germination. Kbar et al. pointed out that as the plant grows and develops, it enters the vegetative growth stage, gradually increases its tolerance to salinity, and becomes sensitive to saline-alkali stress in the reproductive growth stage. Therefore, further research is needed on the identification conditions and indicators of rice alkali resistance and the optimal identification period.

The germplasm resource bank can use equipment to control the storage environment and store the crop germplasm for a long period of time. Also known as the gene bank. The germplasm resource bank of crops can preserve and collect seeds of various crop varieties and store them scientifically, which is of great significance for improving varieties and breeding new varieties with high yield, high quality, and strong resistance.

Gravity Casting Parts

"Gravity Die Casting. A permanent mould casting process, where the molten metal is poured from a vessle of ladle into the mould, and cavity fills with no force other than gravity, in a similar manner to the production of sand castings, although filling cn be controlled by tilting the die."

Gravity Die Casting

Sometimes referred to as Permanent Mould, GDC is a repeatable casting process used for non-ferrous alloy parts, typically aluminium, Zinc and Copper Base alloys.

The process differs from HPDC in that Gravity- rather than high pressure- is used to fill the mould with the liquid alloy.

GDC is suited to medium to high volumes products and typically parts are of a heavier sections than HPDC, but thinner sections than sand casting.

There are three key stages in the process.

  1. The heated mould [Die or Tool] is coated with a die release agent. The release agent spray also has a secondary function in that it aids cooling of the mould face after the previous part has been removed from the die.
  2. Molten metal is poured into channels in the tool to allow the material to fill all the extremities of the mould cavity. The metal is either hand poured using steel ladles or dosed using mechanical methods. Typically, there is a mould [down sprue" that allows the alloy to enter the mould cavity from the lower part of the die, reducing the formation of turbulence and subsequent porosity and inclusions in the finished part.
  3. Once the part has cooled sufficiently, the die is opened, either manually or utilising mechanical methods.

Advantages

  • Good dimensional accuracy
  • Smoother cast surface finish than sand casting
  • Improved mechanical properties compared to sand casting
  • Thinner walls can be cast compared to sand casting
  • Reverse draft internal pockets and forms can be cast in using preformed sand core inserts
  • Steel pins and inserts can be cast in to the part
  • Faster production times compared to other processes.
  • Once the tolling is proven, the product quality is very repeatable.
  • Outsourced Tooling setup costs can be lower than sand casting.

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