Studies on Direct-seeding Adaptability of Cambodian Rice Cultivars and Development of Cultivars with Good Eating Quality@@
PDEffects of Temperature, Sowing Depth and Soil Hardness on Seedling Establishment
and Yield of Cambodian Rice Direct-seeded in Flood Paddy Fields
Ly Tong, T.Yoshida, T.Maeda and H.Kimijima. PPS 10(1):129-153(2007.1).
Cambodian rice cultivars showed a low seedling establishment rate at a low temperature or deep sowing condition. Cambodian cultivars had a short plant length and short basal low internodes, which contributed to strong lodging resistance. They had a potentially high yield due to a high number of stems per plant and in some cultivars a high number of spikelets per panicle. Crossing of Cambodian cultivars with Koshihikari to obtain cultivars
adapted to direct-seeding in Cambodia was proposed.
2.Can Hot-Water Emasculation Be Applied
to Artificial Hybridization of Indica-Type Cambodian Rice?
Ly Tong and Tomohiko Yoshida. PPS (2008)@11(1):132-133.
The panicles with only spikelets at flowering time of indica-type Cambodian rice were submerged in hot water (40 - 46) for 7 minutes. The panicles after the treatment were grown in the natural condition for 7 days, and the number of spikelets fertilized by self-pollination was counted. The numbers of fertilized spikelets per panicle were 7.1, 0.1 and 0 in the panicles treated with hot water at 40, 43 and 46, respectively, as the average of 11 Cambodian cultivars in the experiment in 2005, and 3.6, 0.1, 0, 0.06 and 0 at 40. 43, 44, 45 and 46, respectively, as the average of 5 Cambodian cultivars in the experiment in 2006. In the other experiment, the panicles with only spikelets at flowering time of indica-type Cambodian rice were submerged in hot water (40 - 46) for 7 minutes, but the spikelets after the hot-water treatment were artificially pollinated with healthy pollen of Koshihikari, W42 or Srau Sar. The percentages of fertilized spikelets in the panicles treated at 43, 44, 45 and 46 were 36.0, 23.6, 13.0 and 0.3%, respectively, as the average of 11 Cambodian cultivars in 2005, and those treated at 44,45 and 46 were 21.9, 11.7 and 10.6%, respectively, as the average of 5 Cambodian cultivars in 2006. These results showed that female organ in more than 20% of the spikelets were tolerant to hot-water treatment at 43 or 44 for 7 min, although most of the pollens were inactivated by these treatments. Thus, the hot-water treatment at 43 or 44 for 7 minutes is useful for emasculation of indica-type Cambodian rice.
3.Genetic Diversity of Cambodian Rice Cultivars.
Ly Tong and Tomohiko Yoshida. PPS 11(3):366-367 (2008).
The authors aimed to characterize population structure and demographic history of 18 Cambodian and Japanese cultivars as fundamental information by employing the simples sequence repeats (SSRs). The author roughly divided all the genotypes into three groups. All cultivars (except Rohat) in ggroup Ah are traditional cultivars and ggroup Bh (except Phka Mlis) includes cultivars, which have the genetic relationship to IR lines (Men et al. 2001). Rumpe was placed in group C, even though, it is indica and has genetic relationship to IR lines, and it might have closed genetic relationship to japonica type.