Upland Rice and Allelopathy

Upland rice (Oryza sativa L.) is mainly grown in Asia, Africa and Latin America. Yield potential of upland rice is quite low and invariably this crop is subjected to many environmental stresses. Further, when upland rice is grown in monoculture for more than two to three years on the same land, allelopathy or autotoxicity is frequently reported. Allelopathy involves complex plant and plant chemical interactions. The level of phytotoxicity of allelochemicals is influenced by abiotic and biotic soil factors. Adopting suitable management strategies in crop rotation can reduce or eliminate allelochemicals phytotoxicity. Rice yields can be improved by growing rice in rotation with other crop species. Allelochemicals of rice can be used for control of weeds in this crop as well as other crops that are grown in rotation with rice. This review highlights that present knowledge of allelopathy in upland rice is inadequate and fragmentary, and therefore, more controlled and field studies are needed to understand and to reduce the detrimental effects of allelopathy in the upland rice production

RANDOM AMPLIFIED POLYMORPHIC DNA ANALYSIS OF AUSTRALIAN RICE (ORYZA-SATIVA L) VARIETIES

The genetic relationships between rice varieties were analysed by using the polymerase chain reaction (PCR), with arbitrary oligonucleotide primers in the random amplified polymorphic DNA (RAPD) method. PCR with 22 arbitrary primers applied to 37 varieties produced 144 useful markers, of which 67% were polymorphic. Thus, with selected primers sufficient polymorphism could be detected to allow identification of individual varieties. Visual examination of electrophoresis gels and analysis of banding patterns confirmed that commercial Australian and USA lines and their relatives were very closely related, with similarity indices of 88-97%. Three varieties originating from more distant geographical centres were easily distinguished, producing variety-specific amplification profiles and expressing a lower similarity index of 80% to all other varieties tested. PCR offers a potentially simple, rapid and reliable method for rice genotype identification and recognition of lines that could contribute genetic diversity to new commercial varieties

The Sloan Digital Sky Survey-II Supernova Survey: Technical Summary

The Sloan Digital Sky Survey-II (SDSS-II) has embarked on a multi-year project to identify and measure light curves for intermediate-redshift (0.05 < z < 0.35) Type Ia supernovae (SNe Ia) using repeated five-band (ugriz) imaging over an area of 300 sq. deg. The survey region is a stripe 2.5° wide centered on the celestial equator in the Southern Galactic Cap that has been imaged numerous times in earlier years, enabling construction of a deep reference image for the discovery of new objects. Supernova imaging observations are being acquired between September 1 and November 30 of 2005-7. During the first two seasons, each region was imaged on average every five nights. Spectroscopic follow-up observations to determine supernova type and redshift are carried out on a large number of telescopes. In its first two three-month seasons, the survey has discovered and measured light curves for 327 spectroscopically confirmed SNe Ia, 30 probable SNe Ia, 14 confirmed SNe Ib/c, 32 confirmed SNe II, plus a large number of photometrically identified SNe Ia, 94 of which have host-galaxy spectra taken so far. This paper provides an overview of the project and briefly describes the observations completed during the first two seasons of operation