The effect of different irrigation intervals and plant densities on yield and yield components of two fennel (Foenicolum vulgare) landraces

In order to investigate the effect of different irrigation intervals and plant densities on yield and yield components of two fennel landraces, an experiment was conducted at the agricultural research station, Ferdowsi University of Mashhad in 2003 and 2004. For this purpose a double split plot experiment based on a Complete Randomized Block Design with three replications was used. Treatments included three irrigation intervals (10, 20 and 30 days), two fennel landraces (Khorasan and Kerman) and four plant densities (40, 50, 67 and 100 plant per m2). Row spaces were kept constant (25 cm) and plant density were adjusted in row spaces. Results indicated that irrigation affected vegetative and reproductive organs, significantly. With increasing irrigation intervals, plant height, dry matter of stem, total dry matter of plant, lateral branches per m2, umbels per m2, umbels per plant, fertile umbels per main stem, umbels per lateral branch, umbelets per umbel, 1000-seed weight and grain yield were decreased, but main branches per m2 and grain number per umbelet did not show a constant trend. Khorasan landrace had more plant height and 1000-seed weight than Kerman landrace, but main branches per m2, lateral branches per m2, umbels per m2, umbels per main branch, umbelets per umbel, grain number per umbelet and grain yield in Kerman landrace were higher than Khorasan landrace. Two landraces showed no differences in dry matter of stem weight, total dry matter of plant, umbels per plant and umbels per lateral branch. With increasing plant density, umbels per plant, umbels per main branch, umbelets per umbel and grain number per umbelet decreased, significantly. Density had no significant effect on 1000-seed weight. With increasing density, dry matter of stem, total dry matter of plant, main branches per m2, lateral branches per m2, umbels per m2 and grain yield increased, but umbels per lateral branch showed no constant trand. Our results showed that the maximum grain yield was obtained in Kerman landrace with 10 days irrigation interval and 100 plants per m2.