Resilience of rice (Oryza spp.) pollen germination and tube growth to temperature stress. uri icon

abstract

  • Resilience of rice cropping systems to potential global climate change will partly depend on the temperature tolerance of pollen germination (PG) and tube growth (PTG). Pollen germination of high temperature-susceptible Oryza glaberrima Steud. (cv. CG14) and Oryza sativa L. ssp. indica (cv. IR64) and high temperature-tolerant O. sativa ssp. aus (cv. N22), was assessed on a 5.6-45.4 degrees C temperature gradient system. Mean maximum PG was 85% at 27 degrees C with 1488 mu m PTG at 25 degrees C. The hypothesis that in each pollen grain, the minimum temperature requirements (T-n) and maximum temperature limits (T-x) for germination operate independently was accepted by comparing multiplicative and subtractive probability models. The maximum temperature limit for PG in 50% of grains (T-x(50)) was the lowest (29.8 degrees C) in IR64 compared with CG14 (34.3 degrees C) and N22 (35.6 degrees C). Standard deviation (s(x)) of T-x was also low in IR64 (2.3 degrees C) suggesting that the mechanism of IR64's susceptibility to high temperatures may relate to PG. Optimum germination temperatures and thermal times for 1 mm PTG were not linked to tolerating high temperatures at anthesis. However, the parameters T-x(50) and s(x) in the germination model define new pragmatic criteria for successful and resilient PG, preferable to the more traditional cardinal (maximum and minimum) temperatures.

publication date

  • 2016
  • 2016
  • 2016