Studies on some ecophysiological traits associated with competitiveness of old and new Iranian bread wheat (Triticum aestivum L.) cultivars against wild oat ( Avena ludoviciana L.)

Abstract

An experiment was conducted during 1996-1997 growing season in Mashhad, NE of Iran to evaluate the genetic improvement in ecophysiological traits that enhance the competitiveness of Iranian winter wheat (Triticum aestivuml) against wild oat ( Avena ludovicianal). Six Iranian winter wheat cultivars which have been released during the past 40 years were used for this experiment. A factorial experiment was arranged in a randomized complete block design with three replications. Each cultivar was planted at its own optimum seeding rate with and without competition with wild oat. Wild oat was planted at a constant density of 80 plants per square meter. The results showed that more recent cultivars had much higher competitive ability compared to earlier cultivars. Alvand (the most recent cultivar) had higher dry matter accumulation, crop growth rate (CGR), leaf area index (LAI) and relative leaf area growth rate (RLGR) compared to Bezostaya. Alvand had a higher proportion of its leaf area in higher canopy layer. Wild oat was also shorter in height when it was competing with Alvand compared to Bezostaya. It was found that following characteristics were the most important criteria in competitive ability of winter wheat against wild oats: 1) leaf area at the end of tillering stage. 2) final leaf area index. 3) relative leaf area index, and 4) the canopy layer where the higher leaf area was measured