GROWTH CHARACTERISTICS, YIELD COMPONENTS AND RATE OF GRAIN DEVELOPMENT OF TWO HIGH-YIELDING WHEATS, HY320 AND DT367, COMPARED TO TWO STANDARD CULTIVARS, NEEPAWA AND WAKOOMA

Abstract

A high-yielding Canada Prairie Spring (CPS cv. HY320) semi-dwarf wheat and a high-yielding durum line (DT367) were compared to standard hard red spring (cv. Neepawa) and durum (cv. Wakooma) wheats to assess the basis for the yield differences and to examine soil moisture use. The study was carried out under dryland (moisture used from seeding to harvest was 287 mm), partial irrigation (moisture used was 374 mm) and full irrigation (moisture used was 547 mm) on a loam soil at Swift Current during 3 yr. Phenological development was delayed as much as 30 d by improved moisture conditions. At ligule of last leaf visible (LLV), HY320 had one or two more green leaves on the main tiller than did Neepawa; Wakooma generally had one more leaf than DT367. However, leaf area index was generally not different among cultivars. Harvest index was greater for the higher yielding cultivars even though cultivars did not differ in total aboveground dry matter. HY320 generally had the highest grain yield, followed by DT367, Wakooma and Neepawa. Neepawa consistently had the most heads per unit area at harvest but, because of high kernel numbers per head, HY320 produced the greatest number of kernels per unit area; as well, HY320 had large kernels; thus, it had the highest yield potential under optimum growing conditions. HY320 had the highest base temperature (Tb) for kernel growth and the highest kernel growth rates immediately after anthesis; consequently, HY320 kernels completed growth with the lowest accumulated degree days above Tb. DT367 had the highest potential kernel weight and Neepawa the lowest. There were no differences among the cultivars in the amount of moisture used between seeding and harvest.Key words: Wheat (Spring), yield components, grain development, moisture use, growing degree days, harvest index