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In order to study the relationship between forage yield and Morphologycal Characteristics, 31 genotypes of standard crested wheatgrass (Agropyron desertorum Fish.ex Link) in a Randomized Compeletely Block Design(RCBD) with 3 replications, were evaluated in 2 seperate experiments including dry farming and rainfed conditions,condensely, in plots (dimention of 1×2 m) in Islamic Azad University, Arak Branch. Traits such as date of spike appearance, date of pollination, plant height, spike length, spikelet number per spike, size of flag leaf, length of peduncle, thousand grain weight, stem number per plant, seed weight per spike, seed number per spike, harvest index, seed yield and forage yield were measured. Phenotypic correlation analysis indicated that forage yield has a positive and significant correlation in 1% level, with traits such as plant height (r=0.60), number of stems per plant (r=0.46) and seed yield (r=0.44). Obtained results from stepwise regression analysis for forage yield as a dependent variable, indicated significant effects of stem number per plant, date of spike appearance, harvest index, seed yield and seed weight per spike on forage yield with R2=0.93. According to Path analysis, seed yield and harvest index had the most direct effect and also seed yield had the most indirect effect (through a decrease in harvest index) on forage yield.

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In order to investigate the relationship between effective traits on seed yield of two maturity groups of soybean, an experiment was conducted as randomized complete block design with three replications at Agricultural Research Farm, University of Guilan in 2009. The experimental treatment was seven soybean cultivars, namely 033, 032, Sahar (belonged to maturity group IV), L.17, Zan, Clark and Madari (belonged to maturity group III). The studied traits were included number of pods on the main stem and on branches, number of pods per plant, number of seeds per pod, 1000 seed weight, plant weight, weight of seeds per plant, number seeds per plant, oil and protein percentage, seed yield and biological yield and harvest index. Simple correlation between traits, stepwise regression and path analysis were carried out in maturity group separately. The results showed biological yield trait in maturity group IV and weight of seeds per plant ,had the highest positive and meaningful correlation with seed yield. Stepwise regression analysis showed that these traits covered majority of total yield changes Then , the entered traits in. regression model were studied , and based on in it in group maturity IV, biological yield trait(r=1.04) and in group maturity III weight of seeds per plant (r=0.80) had majority of direct and positive effect on seed yield. Therefore any maintaining or planting activities in order to improve these traits ,can increases Soybean yield.