Potted plants were planted in 3 replicates. Repeated internal test materials were randomly arranged. Walkways were 1m wide. The pots and pans were placed in parallel on a well-prepared soil surface with a spacing of 80 cm, a length of 2 m, a width of 40 cm, and a height of 40 cm. The SPAD502 chlorophyll meter was used to determine the relative chlorophyll content (spad value) in the middle position of the leaf in the panicle. The chlorophyll a content and chlorophyll b content were determined by spectrophotometry, and the chlorophyll a/b value was calculated.
Under shading conditions, the comprehensive shade-tolerance coefficients of 18 hybrid varieties and 30 inbred lines were calculated based on the leaf area and chlorophyll content of maize ear. The chlorophyll b content in shade and wet environment increased by 65.41% compared with the natural environment, and the difference was extremely significant; the chlorophyll a/b value was 1.89±1.19, the coefficient of variation was 63.40%, and the chlorophyll a/b value in shade and wet environment was lower than the natural environment by 32.25%. Extremely significant.
Under artificially simulated shaded and wet conditions, the differences in ear leaf area and chlorophyll content of different genotype maize under shaded wet and natural conditions were compared. The results of the above chlorophyll meter showed that the shade and wet environment had a significant effect on leaf area, chlorophyll and its content in maize ear, and the ear leaf area and chlorophyll a/b value of hybrid maize and inbred lines in shade and wet environment. All showed a downward trend, and the relative contents of chlorophyll and chlorophyll b content showed a significant upward trend. There was a significant or extremely significant difference in the genotypes of these traits.
A needle roller bearing is a special type of roller bearing which uses long, thin cylindrical rollers resembling needles. Ordinary Roller Bearings' rollers are only slightly longer than their diameter, but needle bearings typically have rollers that are at least four times longer than their diameter.Like all bearings, they are used to reduce the friction of a rotating surface.
Compared to Ball Bearings and ordinary roller bearings, needle bearings have a greater surface area in contact with the races, so they can support a greater load. They are also thinner, so they require less clearance between the axle and the surrounding structure.
Needle bearings are heavily used in automobile components such as rocker arm pivots, pumps, compressors, and transmissions. The drive shaft of a rear-wheel drive vehicle typically has at least eight needle bearings (four in each U joint) and often more if it is particularly long, or operates on steep slopes.
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