Study On The Panicle Traits And Microclimate In Population Of Erect Panicle Mutant R499

Panicle type is an important part of the plant type in rice, but the application of erect panicle type is rarely studied in Indica rice. With an aim of providing a theoretical basis for the high yield breeding of Indica rice, this research compared the microclimate characteristics of populations of different panicle types. The curved panicle type rice was Shu Hui 498(R498),erect panicle mutant 499(R499) and semi erect panicle mutant 816(R816) were all produced by EMS mutation. This paper studied on the reasons of erect panicle type rice upright, and analyzed the variations of panicle agronomic traits and microclimate in different panicle type rice. The research conclusions were as follows:1. The variations of panicle bending indicated that panicle bending in all rice verieties had significant difference. The panicle bending of mutant R499 was less than 45°, which belonged to the erect panicle type rice varieties. While the panicle bending of mutant R816 was between 45° and 90° at 20 d after heading,and belonged to semi erect panicle type rice varieties. The panicle bending of wild type R498 had been more than 90° 12 d after heading, which belonged to the curved panicle rice varieties.2. The length of erect panicle mutant R499 shortened about 17% compared with wild type, while there was no significant difference between semi-erect panicle and curved panicle type. In terms of ability on panicle resistance to bending, it showed erect panicle> Semi-erect panicle> curve panicle. The diameter of rachilla, diameter of the upmost stem, number of vascular bundles and other aspects of erect panicle mutant were significantly higher than the wild-type. Panicle transverse resistance of semi-erect panicle type was significantly greater than the wild type. The mutant R499 The panicle modality of erect panicle mutant was compact, and it had more number of vascular bundles and thicker diameter of panicle neck. Therefore erect panicle mutant had greater mechanical strength, which could help its panicle keep erect.3. The development of young panicle showed that there was no significant difference in early development of young panicle stage of all rice varities. But inlater development, it showed a significant difference between the mutants and wild type. The length of primary branches showed similar changes in different periods. And the maximum of the differences appeared in stage VI.4. The microclimate in population of erect panicle mutant R499 was showed a much better than in that of curved panicle type. The permeability in the middle and lower part of Shu Hui was greatly different from that of R499.When the environmental wind speed was 4.5 m/s, the middle wind speed in R499 was 44.44% higher than that in Shu Hui 498, and the lower wind speed27.90% higher. The light intensity of 20-80 cm under the canopy decreased in a much slower velocity in the erect panicle type groups than in the curved panicle type groups. Therefore the light intensity among the middle and lower leaves was much higher in the erect panicle groups than in the curved panicle type groups from 8:00 am to 16:00 pm, ensuring greater light-receiving rate of middle and lower leaves in the erect panicle rice groups. The temperatures in the middle and lower part of erect panicle type groups were higher than that of curved panicle type groups, while the humidity was relatively lower. For Semi-erect panicle mutant R816, the permeability was in between R498 and R499, the same as temperature and humidity.Above all, since the panicle type was the only difference between the mutants and wild type, it could be considered as an important factor that leads to the difference in the microclimate characteristics of the Indica rice populations.