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Excess rainfalls may be the cause of waterlogging in soil, which affects the growth and development of wheat. Therefore, the objectives of this study were to examine the effects of waterlogging on shoot and root growth and physiological characteristics of wheat. Three experiments were conducted: experiment 1 (E1): evaluation of seedling growth on ten Iranian winter wheat varieties with waterlogging periods (1-4, 4-8, 8-12, and 12-16 days starting from seed germination). Seminal roots and plumule were investigated at seedling. The others are E2: pretreatment of waterlogging (15 days) at tillering and stem elongation stages and its effects on shoot and root growth at anthesis stage and experiment 3 (E3): pretreatment of waterlogging (15 days) at tillering and jointing stages and its effects on yield and yield components and also evaluation of stress tolerance indexes. The results of the seedling growth test (E1) showed that 1-4- and 4-8-day waterlogging severity reduced seminal root length (94.5 to 93.7 %) and plumule length (86.2 to 50.0 %) compared to control. Results of E2 indicated that waterlogging stress decreased shoot dry weight, root dry weight, total secondary root length, and chlorophyll a + b content of flag leaf by 28-31, 44-35, 20-31, and 28-35 %, respectively. Also, result of E3 showed that the grain yields of wheat varieties at two conditions of stress were different in base tolerance indexes. In general, the responses of wheat varieties to waterlogging were different at the three experiments. The varieties that had the most of dry weight and length of the root were tolerant. Thus, it is possible to use these characteristics as an index for selecting the varieties with tolerance to waterlogging.

A field study was conducted at the Agricultural Research Farm of Razi University, Kermanshah, Iran to investigate the effects of phosphate biofertilizer, row spacing and plant density on corn yield and weed growth. The experiment was a factorial with three factors arranged in a randomized complete block design with three replications. The first factor was phosphate biofertilizer (inoculation and non-inoculation), the second was row spacing (conventional (75 cm) and reduced (50 cm)) and the third was plant density (66,666 plants·ha -1 (conventional plant density) 83,333 and 99,999 plants·ha -1 (1.25 and 1.5 times the conventional plant density, respectively)). Results indicated that corn yield and weed growth were significantly influenced by row spacing and plant density. So that, corn yield improved and weed biomass diminished in response to increasing plant density and decreasing row spacing. However, phosphate biofertilizer had no significant effect on corn yield, whereas, weed biomass was notably increased when phosphate biofertilizer was applied. Overall, this study revealed that both yield and weed control in corn field can be improved by alteration of the planting arrangement.

Considering the little amount of research on this crop in Iran and especially in Kermanshah, this paper was devoted to its study. In order to study the effect of sowing date and water stress on yield and yield components and seed sugar content in sweet corn cv.SC403, an experiment was conducted in the research farm and laboratories of the department of agronomy and plant breeding at Razi University, Kermanshah, in 2008. This investigation was performed as a factorial experiment based on randomized complete block design (RCBD) with four replications. The sowing date factor included four dates (4 May, 24 May, 13 June and 3 July) and three levels of water stress (control, moderate and severe water stress). The accumulated evaporation included: 70 (control), 120 (moderate water stress) and 170 (severe water stress) from evaporation pan class A. With respect to the results of this experiment, if the purpose in sowing of sweet corn is quantitative yield, the 3 rd of July under no water stress treatment (control) will be the best date (8547.2 kg ha-1). The sowing date of 3 rd July and the moderate water stress treatment did not have significant effect on quantitative yield. Thus, in arid and semi arid areas such as Kermanshah where water saving is important, this sowing date maybe very useful for water saving. But if the purpose is to have high qualitative yield in sweet corn (seed sugar), the sowing date of 4 May under severe water stress (1.48% sucrose) maybe the best choice.

Character association and path analysis were performed for black seed cultivars using a split-plots design based on RCBD with three replications. Three cultivars ('Varzaneh' , 'Semirom' and 'Mobarakeh') were studied under three levels of irrigation (normal irrigation, irrigation with drought stress before and after flowering). Under normal and abnormal irrigations the relation of seed yield and three characters biological yield, number of capsule per plant and thousand seed weight were high, positive significantly (p≤0.01); the relation between yield and number of sub branch was positive significantly (p≤0.05). In terms of abnormal irrigation there was a positive significant correlation between essence percent and yield (p≤0.05). Under normal irrigation the most direct effect of traits on yield was obtained from biological yield (0.778) followed the number of capsules per plant (0.245). The most indirect effect of traits on yield was obtained from biological yield through thousand seed weight (0.576) followed stem diameter through biological yield (0.468). Under water deficiency conditions the most direct effect of traits on yield was obtained from biological yield (0.811) followed the number of capsules per plant (0.231). The most indirect effect of traits on yield was obtained from biological yield through thousand seed weight (0.562).