TY - JOUR ID - 27108 TI - Effects of drought stress and defoliation on sunflower (Helianthus annuus) in controlled conditions JO - Desert JA - JDESERT LA - en SN - 2008-0875 AU - Nezamia, A. AU - Boroumand Rezazadehb, Z. AU - Hosseini, A. AD - Assistant professor, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran AD - PhD Scholar, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran AD - Graduate Student, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran Y1 - 2007 PY - 2007 VL - 12 IS - 2 SP - 99 EP - 104 KW - defoliation KW - Drought stress KW - Plant height KW - Seed weight KW - Sunflower DO - 10.22059/jdesert.2008.27108 N2 - Abstract In order to evaluate the effects of drought stress and defoliation on sunflower, a study was conducted under controlled conditions. Treatments were a combination of three levels of drought ((100, 60 and 30 percent of Field Capacity (FC)) and three levels of defoliation (control, removal of either 4 or 6 leaves from lower part of the plant) laid out, in a Completely Randomized Design with four replications. Drought stress was applied from 4-leaf- stage up to the end of plant growth period while leaf removal was conducted at the heading stage. Results indicated that drought stress affected most of the measured parameters. Plant height, plant dry matter, stem diameter, head size, seed number/head, 100-seed weight and seed weight/ head declined upon drought stress as compared to control. SPAD readings increased as drought stress increased. Defoliation caused an increase in SPAD and a decrease in seed number/head. Leaf number was not affected by either drought or defoliation. Keywords: Defoliation; Drought stress; Plant height; Seed weight; Sunflower UR - https://jdesert.ut.ac.ir/article_27108.html L1 - https://jdesert.ut.ac.ir/article_27108_44e0ce85ead30656d568e0f8e72effa5.pdf ER -