Z Daneshvar Ran, M Esfahani, M Payman, M Rabiei, H Samie Zadeh,
Volume 12, Issue 46 (fall 2009)
Abstract
The effects of tillage methods and residual management on yield and yield components of rapeseed (Brassica napus L. CV. Hyola308) were evaluated after rice harvest. The experiment was carried out during 2004-2005 cropping season in a factorical arrangement of treatments at Rice Research Institute of Iran (RRII) in Rasht, in a Complete Randomized Block Design with three replications. Treatments included tillage in three methods: a) conventional tillage b) minimum tillage, and c) no tillage, and rice residue management in two manners: a) removing residues, and b) not removing residues. Plant traits such as grain yield, oil percentage and yield, plant density, plant height, the lowest pody branch height from soil surface, number of pods per plant, plant and weed dry weight, leaf area index (LAI) and crop growth rate (CGR) were measured. Results indicated that grain yield was affected by the tillage type. Also, the effect of tillage type on plant height, number of pods per plant, the lowest pody branch height from soil surface, and oil yield was significant. The effect of residual management and residual management interaction and tillage were significant on none of the traits except for weed dry weight. Economic analysis indicated that rapeseed planting in a field with rice residual and minimum tillage had a relative advantage of less production cost in spite of nearly 15 percent yield decrease compared to other methods.
S Safae Chaykar, H Samie Zade, M Esfahani, B Rabiei,
Volume 13, Issue 48 (7-2009)
Abstract
In order to study the correlation of agronomic, morphologic and physiologic traits and their effects on grain yield of rice genotypes in two environments (favorable irrigation and water stress), 49 genotypes were evaluated using a completely randomized block design with 3 replications in two experimental conditions. All practices and conditions were the same for the two experiments with the exception of irrigation, where under stress conditions no irrigation was applied at tillering stage. Comparison of means showed significant differences between genotypes in each environment. Also, differences between yield and yield components of each genotype under two conditions were significant. The results of phenotypic correlations showed that the highest positive and significant correlation with grain yield belonged to number of panicle per plant (0.95) in irrigation conditions and to number of filled grains per panicle (0.92) in water stress conditions. Stepwise regression analysis for grain yield introduced number of panicle per plant, relative water content (RWC), flag leaf length and number of spikelet per panicle, respectively, as effective traits in grain yield in irrigation conditions, however, in stress conditions, number of filled grain per panicle, number of panicle per plant and relative water content were effective traits in yield. The results of path analysis showed that the number of panicle per plant had the highest positive and direct effect on grain yield in the two environments. Factor analysis introduced four factors in the two conditions named yield and crop production, phenologic, harvest index and plant shape and appearance quality of grains factors. Therefore, to select high yield and drought tolerant genotypes, we need to consider number of filled grain per panicle, number of panicle per plant and relative water content. In addition, traits such as panicle length, number of spikelet per panicle, flag leaf length and width that showed significant correlations with grain yield in stress conditions should also be considered important and second to the above mentioned traits.
