The purpose ofthe study was to determine degree of sensitivity to vernalization and response to the natural short daylength of a set of winteíwheat varieties from the Central Asia, South Caucasus, Russia, Ukraine and Turkey. Material of the experiment included 76 varieties from the Central Asia, 14 varieties from the Azerbaijani multi-location trial, 7 varieties from Russia, Ukraine and Kazakhstan, 29 varieties-testers for Ppd and Vrn genes, 39 advanced lines, 271ocal varieties of Azerbaijan and 7 varieties from the crossing block. In total, 200 varieties, each represented by a population of 10 individual plants in 2 replications were investigated. To evaluate genotypic response to short day length, material was planted in late fall (November 14, 2001) at short photoperiod ( 11-13 hour) and exposed to 90-100 days of natural vemalization. Sensitivity to vemalization was studied through spring planting, which was carried out at the relatively long day length (15-hour photoperiod) on May 23. Emergence was observed on June 3. Besides, all genotypes were placed in a refrigerator at three different dates and exposed to artificial vernalization of different length: I) 60-day vernalization -plants placed in the refrigerator on April 3, 2) 45-day -placed in the refrigerator on Apri1 18, and 3) 30-day -placed on May 3. The vernalized plants were planted on the same field on June 3. Evaluation ofthe fall-planted material showed a significant variation in heading date. The difference between the most contrasting varieties in terms of response to short photoperiod was as high as 56 days. The test varieties headed in the following order: Sharbati Sonora (neutral, photoperiod-insensitive, possibly carrying 4 dominantPpd genes, heading on April14, 2002), Sl.(orospelka 35 (slightly sensitive, carrying 3 Ppd genes, heading on April 30), Saratovskaya-29 (relatively sensitive, carries 2 Ppd genes, heading on May 17), Ulyanovka (strongly sensitive, one dominant gene, heading -May 30), Warden ( extra-sensitive, all genes recessive, heading on July 9). Analyses ofheading dates of76 varieties from the Central Asia have shown a 21-day range of variability. The most photoperiod sensitive appeared variety Yan Bash(heading date May 15). Variety Simoni showed the lowest sensitivity (heading date ApriI25). The degree of sensitivity of the varieties from Central Asia varied between slightly sensitive and relatively sensitive types, as we found no genotypes with insensitive, strong and extra-strong response among them. Among the 14 varieties from theAzerbaijani multi-location trial, the most sensitive was variety Fransa (heading date May 5), while variety Samur was the least sensitive ( April 18). Among the 39 advanced lines heading date varied within 14 days. The most sensitive was found to be line K -02024/8 (May II ), while the earliest heading dates were observed for lines K-0887/2- 18, K-01743/1 , and Lutescense (ApriI27). Among the local varieties of Azerbaijan, Tartar-2 appeared to be the most sensitive (May 19), while Qiymetly-80 was found to be the least sensitive to photoperiod. For the genotypes with intermediate dates ofheading, earliness per se is presumed. Among the 200 spring-planted genotypes without preliminary vemalization, 103 were found to be winter wheats. Winter growth habit was identified for 32 out of76 Central Asian genotypes and 3 out of 14 included in the Azerbaijani multi- location trial. While all 7 varieties from Russia, Ukraine and Kazakhstan demonstrated the winter- growth habit. The analysis of data obtained from the study with preliminary vemalization suggests that 9 winter wheat genotypes headed only after 60-day vernalization, while for 8 varieties 45-day vernalization was enough to head after spring planting. Other 86 winter wheats managed to head after 30-day vernalization. A tendency of earlier heading was observed for the material exposed to 60-day vemalization as compared with the 30-.and 45-day vernalization variants. The other impoftant finding was that the genotypes with higher response to vemalization are generally fou~~ to be more sensitive to daylength. AII lotal varieties of Azerbaijan without exception demonstrate slight sensitivity to short daylength. It is probably associated with the historical adaptation of the local varieties to the local environment, as this sensitivity allows formaximum realization of grain yield potential. Demonstration of the absence of strongly sensitive to vernalization genotypes is also associated with the adaptation mechanisms ofthe local winter varieties. Soft winter is common for Azerbaijan and, therefore, all forms ofwheat, be it winter, summer or emmer, are not affected by very low temperatures during the fall planting period. It is natural that the identified winter varieties should not require long vemalization (45 and 60 days in our case).

Global Wheat Program

English

0407|AGRIS 0401|AL-Wheat Program

Juan Carlos Mendieta

INT1787

CIMMYT Staff Publications Collection