Contribution of CIMMYT Wheat Germplasm to Genetic Improvement of Grain Yield in Spring Wheat of Sichuan, Yunnan, Gansu, and Xinjiang Provinces

Information on advances in wheat (Triticum aestivum L.) productivity is essential for genetic improvement on yield potential. Four yield potential trials with totally 59 leading cultivars from Sichuan, Yunnan, Gansu, and Xinjiang, China were conducted using a randomized complete block design with 3 replications under controlled environments in 2 successive cropping seasons from 2007 to 2009. The experimental sites were located in Chengdu in Sichuan, Lijiang in Yunnan, Wuwei in Gansu, and Changji in Xinjiang. Molecular markers were used to detect the presence of dwarfing genes and 1B/1R translocation. The results indicated that the annual genetic gains in yield were 0.73% in Sichuan, 0.34% in Yunnan, 0.58% in Gansu, and 1.43% in Xinjiang. There was no obvious trend of yield component improvement for yield increase in Sichuan; while reduced spikes per square meter and increased kernels per spike were the main factor for yield increase in Yunnan; increased kernels per spike were the main factor for yield increase in Gansu; and increased kernel weight of main spike and harvest index were the main factor for yield increase in Xinjiang, together with the contribution from reduced plant height and earlier maturity. It also indicated that the dwarfing genes Rht-B1b and Rht-D1b were all from International Maize and Wheat Improvement Center (CIMMYT) lines, and the significant progresses of genetic gain in yield in the 4 provinces were mainly due to the direct and indirect use of CIMMYT germplasm. Stripe rust resistance was the main contribution of CIMMYT germplasm in Sichuan and Yunnan; while CIMMYT germplasm contributed to high yield potential with high kernel number per spike, short plant height, and wide adaptability in Xinjiang and Gansu.