Email: seragalnor.yasir.5x@kyoto-u.ac.jp

The Rht, the semidwarf gene of the green revolution, was introduced from the Japanese wheat ‘Norin 10’. However, recent studies highlighted that despite their significant role in the green revolution, Japanese wheat and other traditional Asian bread wheat cultivars are still underexploited for breeding.

In the light of the imminant threat of climate change and the observed temperature rise, which is already being felt, and the urgency to exploit several germplasm sources for better adaption to heat stress, we evaluated a set of 100 Japanese wheat core collections in Sudan to explore their potentiality under the hot, dry- environment of Sudan.

First, we planted the 100 lines in an observation nursery at the optimum sowing date. Out of the 100 lines, 40 flowered and matured during the Sudanese short-growing season (mid-November to mid-March). Then, these 40 lines were further evaluated in replicated trials executed in an alpha lattice design with 10 Sudanese heat-tolerant wheat cultivars in six environments (a combination of seasons, sowing dates and locations; Wad Medani and New Halfa). Mean grain yield ranged from 1778 kg/ha in Wad Medani late sowing to 2917 kg/ha in Wad Medani optimum sowing, averaging 2370 kg/ha across the six environments.

The Japanese wheat cultivars Kantou 107 and Norin 61 had better grain yield than three Sudanese heat-adapted wheat cultivars. In heading time, Naka Soushuu and Kounosu 25 were one week earlier than the earliest Sudanese cultivar ‘Bohaine.’ In grain number per spike, ‘Fujimi Komugi’ and ‘Kanto 107’ had more grains than six Sudanese cultivars while maintaining reasonable seed weight. Interestingly, ‘Norin 75’ had the highest number of spikes/m2, exceeding some Sudanese heat-adapted cultivars.

Considering the big difference between the Japanese and Sudanese environments, it is interesting that some Japanese wheat cultivars performed comparably to the Sudanese heat-adapted high-yielding cultivars.

These findings could encourage a more in-depth exploration of these 40 lines to utilize their unique traits. For example, Sudan is expected to be affected by intensive heat stress; therefore, early maturing varieties would be one of the options to sustain wheat production in Sudan.

In this regard, the earliness observed in Naka Soushuu and Kounosu 25 could be a favorable trait in wheat breeding in Sudan.