EVALUATION OF NEAR-ISOGENIC LINES OF WINTER WHEAT DIFFERING FOR HEADING DATE

Authors: HARO, EDGAR - CIMMYT; Allan, Robert

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/15/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Heading date and photoperiod response are key physiological processes impacting adaptativeness of wheat (Triticum aestivum L.) to diverse environments. Closely related lines called NILs that range 10 days in heading date were developed by transferring early heading character from Early Blackhull (EB) and a derivative (EBD) of EB to Nugaines, a widely adapted U.S. Pacific Northwest (US PNW) wheat variety. The NILs comprised three heading date groups designated as NGN, EBD and EB groups, which headed 0 to 2, 3 to 7, and 9 to 10 days earlier than Nugaines, respectively. The agronomic performance and adaptive potential of these NILs were compared in three different agricultural environments. The greatest yield potential was achieved by the EBD NILs while the EB NILs had the narrowest adaptation but they had high yield potential at the temperate, long growing season site. Earlier heading indirectly enhanced some grain yield components at some environments. Most EB and EBD NILs had longer grain fill durations than their NGN sister lines. High yield potential was not contingent upon longer grain fill duration because some EBD NILs with durations similar to Nugaines were also among the highest yielding NILs. Most of the NILs were photoperiod sensitive and therefore similar to Nugaines. A few NILs were less sensitive than Nugaines yet photoperiod insensitivity was not required to achieve early heading. It is essential to select a wide range of heading dates among early generation lines to achieve the needed adaptation to diverse agricultural environments in wheat production regions having transitional climates similar to the US PNW.

Technical Abstract: Heading date and photoperiod response are key physiological processes that impact adaptiveness of wheat (Triticum aestivum L.) to diverse environments. Near-isogenic lines (NILs) ranging in heading date were developed by transferring early heading character from Early Blackhull (EB) and a derivative (EBD) of EB to Nugaines (NGN), a soft white winter cv. that was widely adapted to the U.S. Pacific Northwest (PNW). We compared the agronomic performances and adaptive potential of these NILs to three different PNW agricultural environments. The NILs comprised three heading date phenotypes designated as NGN, EBD and EB groups, which headed 0 to 2 d, 3 to 7 d, and 9 to 10 d earlier than Nugaines, respectively. The greatest yield potential across all environments was achieved by two EBD NILs, and NIL V58 out-yielded NGN in all tests. The EB NILs had limited yield potential especially for an early-sown, cool, short growing season site. Members of this group had high yield potential at the long growing season site. Some EBD and EB NILs gave enhanced kernel weights and test weights. Grain fill duration was only partially associated with heading date. High yield potential was not contingent upon longer grain fill duration because some EBD NILs with durations similar to NGN were among the highest yielding NILs. Most of the NILs were similar to NGN for photoperiod sensitivity but two EB NILs were less sensitive than NGN. Photoperiod insensitivity was not required to attain earliness. Among these genotypes, early heading involved types described as intrinsic earliness, photoperiod insensitivity, and perhaps combinations of both.