Pinkaset+5 Rice

Pinkaset+5 Rice Variety

The non-glutinous variety Pinkaset+5 came from backcrossing between Pinkaset+4 and Hom Nin mutant non-glutinous rice, in 2 crosses:

• Cross 1

  • Recipient (female): Pinkaset4#78A03
  • Donor (male): Mu8756 (low stomatal density)

• Cross 2

  • Recipient (female): Pinkaset4#117A08
  • Donor (male): Mu3117 (small stomatal size)

Crossing was carried out at the Rice Science Center, Kasetsart University, Kamphaeng Saen Campus, under the research project

Climate Ready Rice: Optimising Transpiration to Protect Rice Yields under Abiotic Stresses

supported by the National Science and Technology Development Agency (NSTDA) and BBSRC–Newton Fund Partnerships since 2017 (B.E. 2560).

In 2018 (B.E. 2561), F1 hybrids were obtained from both crosses. True F1 hybrid plants were then selected and backcrossed to Pinkaset+4, the recipient, giving the BC1F1 population, and plants that received the target genes were selected, namely:

• Blast resistance
• Bacterial leaf blight resistance
• Brown planthopper resistance
• Flash flood tolerance
• Amylose content
• Cooked starch temperature
• Aroma
• Stomatal traits

using the MAS (Marker Assisted Selection) technique.

They were then backcrossed once more to give BC2F1 and allowed to self-pollinate to give BC2F3.

During breeding, some of the BC1F1 population was also allowed to self-pollinate up to BC1F4, and the BC2F3 and BC1F4 populations from both crosses were used to evaluate the efficiency of MAS selection by testing

• Blast resistance
• Bacterial leaf blight resistance
• Brown planthopper resistance
• Flash flood tolerance
• Stomatal density

as well as comparing yields within Kasetsart University and testing in farmers' fields.

The selected Pinkaset+5 lines number 12 lines, which are photoperiod insensitive, fragrant, high-yielding, resistant to blast, bacterial leaf blight and brown planthopper, and tolerant of flash floods, with both white-grained and brown-grained lines, and with amylose and cooked starch temperature properties differing by line.

Outstanding lines

Several Pinkaset+5 lines yield more than 1 ton per rai, and every line is a fragrant rice resistant to FBBB diseases

Although it is generally believed that high stomatal density is associated with high yield, this research found that lines with low stomatal density can also give high yield.

For example

• Pinkaset+5#4E1
  • Yield 1,067 kg/rai
  • Stomatal density lower than Mu8756 (LD)

while the line Mu8756 (LD) gave a yield of only 527 kg/rai

These Pinkaset+5 lines therefore may have good potential for tolerating water deficit.

Table 2

Harvest age, brown rice color, stomatal density, starch properties, cooked starch temperature and yield of the BC2F4 and BC1F5 populations of Pinkaset+5 and the parent lines