Agriculture Reference
In-Depth Information
bread and Chinese noodle quality need to be considered in the breeding programs (He et al.,
2005).
Growth habits, vernalization genes and photoperiod response are of great importance for
optimal adaptation of bread wheat cultivars to specific environment. Because there are
obvious differences in the severity of the winter temperatures and the length of the growing
season in the different wheat zones of China, the distributions of growth habit, vernalization
alleles and photoperiod responsive Vrn-D1 allele in cultivars released among various wheat
zones are largely different. All cultivars released in Zone I should be winter types and carry
recessive alleles at the four vernalization loci. In Zone II, both winter and spring cultivars
may be present and the later usually need to carry a single dominant Vrn-D1 allele. In Zones
III and V, spring cultivars with the single dominant Vrn-D1 allele are frequently released in
the future. In spring-sown Zones VI, VII and VIII, all cultivars should be spring and most of
them carry the strongest dominant vernalization gene Vrn-A1 plus other dominant gene(s).
Wheat cultivars released in the future should carry Ppd-D1a allele with photoperiod
insensitivity except for spring wheats in high latitude northwestern China (especially Zone
IV), and winter wheats in Gansu and Xinjiang.
In addition to powdery mildew and stripe rust, Fusarium head blight [caused by
Gibberella zeae (Sacc.) Petch] is now endemic to main wheat regions, and sharp eye spot
(caused by Rhizoctonia cerealis Van der Hoeven) and take-all [caused by Gaeumannomyces
graminis (Sacc) Arx & D. Olivier var. tritici J. Walker] are also present. It is important that
introductions of foreign wheat and alien genes from wild relative species into Chinese bread
wheats increase their multiple-disease resistance. Introduced cultivars played an important
role in Chinese wheat breeding and production in the past. Over two hundred synthetic
hexaploid wheat accessions from CIMMYT were introduced into China in recent years. Elite
synthetics were crossed and backcrossed with Chinese commercial wheat cultivars for
improving stripe rust resistance and yield potential. Four synthetic derivatives, Chuanmai 38,
Chuanmai 42, Chuanmai 43 and Chuanmai 47, have been released in Zone V in recent years.
Of them, Chuanmai 42 with large kernels and resistance to stripe rust, had the highest average
yield (> 6 t/ha) of any cultivar over two years in Sichuan provincial yield trials, outyielding
the commercial check cultivar Chuanmai 107 by 22.7%. Chuanmai 42 increased yields by
0.45-0.75 t/ha in farmers' fields (Yang, W. Y., personal communication).
It is very useful for increasing of wheat output and decreasing of input to breed cultivars
with higher water, nitrogen (N) and phosphorus (N) fertilizer use efficiencies in China.
Drought tolerance for rainfed areas should be strengthened because cultivars with drought
tolerance and better water use efficiency are urgently needed. Initially most wheat breeding
programs in China developed cultivars for optimum environments, and few paid attention to
drought tolerance before 1990s even though half of the country's wheat area is rainfed,
particularly in the spring-sown spring wheat region (Zones VI, VII and VIII). At present, the
national program gives priority to breed tolerance or resistance drought cultivars. Cultivars,
such as Jinmai 47, Luohan 2 and Shimai 8 with high water use efficiency, have released.
Some cultivars with higher N and P use efficiencies have been identified. For example,
Abbondanza from Italy and Xiaoyan 6 have higher P absorption efficiency, Nanda 2419 from
Italy, Chengduguangtou and Mazhamai have higher P utilization efficiency; Fengchan 3,
Zhoumai 9, Chuangwu 134, Shixin 5418, Henong 341 and Ji 97-6360 have higher N
utilization efficiency (Li, 2000; Cao et al., 2006; Li et al., 2006). These accessions will be
used to breed cultivars combining higher P and N utilization efficiencies in the future.
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