اثر آللوپاتيك مقادير و سنين مختلف بقاياي آفتابگردان بر سبز شدن و رشد پنبه

Allelopathic effect of different rates and ages on sunflower resisdues of emergence and growth of cotton

Some crops have allelopathic effects. It is important to study their effects on other crop plants, particularly in rotations. A field study was conducted to determine the response of cotton ( Gossypiuni hyrstum L.) to different ages and rates of sunflower (Heliantus annus L.) residues in a randomized complete block desing with 7 treatments and 4 replications at College of Agriculture, Uviversity of Mazandaran, Sari, Iran . Treatments were 80 grams of 6, 8, and 10 weeks - old residues, 160 grams of 6, 8 and 10 weeks- old residues,. and a control treatment (no residue). Measured traits were percent emergence, height, and dry weight of cotton two and six weeks after planting and final height, dry weight, and yield. Results showed that percent emergence, height, dry weight, and yield of cotton were significantly reduced in comparison with control. Increased maturity residue reduced these traits significantly, but residula rate did not cause significant effect. The reduction in percent emergence, height, and dry weight were 62, 59 and 74% two weeks after planting, respectively. In these research residues from older plants were found 1o be more phytotoxic than residues from younger plants.