فصلنامه پژوهشهای زراعی در حاشیه کویر
سال یازدهم شماره 1 (بهار 1393)

In order to evaluate the effect of sowing date on growth analysis, physiological and morphological traits eight rapeseed cultivars, a field experiment was carried out cropping in Bojnourd. The experiment was conducted as split plot design with three replications. Main plot including sowing date (Sep.21, Oct.17) and sub plot were cultivars(Zarfam, Licord, Ebonit, SLM046, Opera, Elvis, Okapi and Orient) Investigated traits included: TDM, RGR, CGR, plant height, crown diameter, sub branches number, pod length, pod per plant, grain per pod, 1000 grain weight and grain yield. Also traits correlation and growth equations were determined based on growing degree day. Result growth analysis showed that sowing date had not significant effect on TDM, RGR and CGR. However, all cultivars were died in the last sowing date, significant Difference occurred among cultivars for growth analysis traits, but sowing date × cultivar had no effect on TDM and CGR. The maximum of growth indices were detected on Oct.17 and Zarfam and Ebonit cultivars had the maximum of growth in this time. Also sowing date had effect on all characters expect 1000 grain weight and grain yield. A positive correlation were observed between grain yield with pod per plant (r= .68**) and sub branches number (r= .43**), respectively. In conclusion, there is no significant difference between the first and second sowing date, so it is seemed that early sowing date is useful for Bojnourd due to protecting from cool injuring. Also between cultivars, Ebonit and Zarfam, in order, have a priority, respectively.

In order to evaluate the effect of irrigation and plant density on the extinction coefficient grain corn delayed, the trial was conducted in the summer of 1390 in the field of Shahid Shalemi in Ahwaz city, This experiment using a split plot design with three replications.Irrigation intervals (I) in three levels, including intervals of five (I1), eight (I2) and 10 (I3) on the main plots and plant density (P) on three levels: 6.7 (P3), 7.8 (P2) and 9.5 (P1) per square meter, or 67, 78 and 95 thousand plants per hectare were in sub plots. Evaluations consisted of leaf area index and light penetration into the canopy in order to calculate K (light depreciation coefficient), respectively. Results showed that irrigation on light extinction coefficient was significant at the one percent level, so that with increasing irrigation intervals, the coefficient is increased. The stress concentration factor and irrigation density and interactions were significant at the one percent level. The highest density of 65000 plants per hectare was obtained extinction coefficient in other words by reducing the leaf area index, light extinction coefficient increased.

To evaluate the priming effect and potassium on yield and yield components of rapeseed cv. Okapi at different planting dates, an experiment was conducted during 2012 at Bojnourd. Factorial experiment in a randomized complete block design with four replications in two planting dates was conducted (1 October and 1 November). Factors examined included two levels of seed priming (non-Prime and priming solution of KNO3 ,-1 MPa for 24 h) and potassium fertilizer levels (zero, 75 and 150 kg K2o. ha). After analyzing the results of two simple planting date, were combined for analysis. Combined analysis of variance showed that all three experimental factors affect the number of pods per plant, grain yield, harvest index, and oil yield had significant impact. Planting date and priming showed a significant effect on 1000 seed weight. Planting date 1 October compared with 1 November, seed priming compared with non- Prime and potassium fertilizer consumption compared with no use, the characteristics were significantly increased. Therefore Planting date 1 October was optimum planting date on canola in the region, and in case of delay in sowing seed, priming done with a solution of KNO3 (-1 MPa for 24 h) or K2o consumption of 75-150 kg per hectare is recommended.

In order to evaluate the effect of irrigation and pattern of nitrogen topdressing on yield and yield components of sunflower, an experiment was carried out in complete block design with split-plot arrangement in three replications during 2012 growing season. Irrigation regimes were allotted to main plots and nitrogen treatments were allotted to sub-plots. Irrigation regimes were consisted of: 1) moderate irrigation 2) water stress at V8 growth stage and 3) water stress at heading stage. The nitrogen treatments were consisted of: N1: 25% at sowing, 50% at V8, 25% at heading; N2: 50% at V8, 50% at heading; N3:50% sowing, 50% heading; the results showed that water stress at heading significantly decreased the head diameter and100-grains weight and non-significantly decreased the grains per head which was resulted to 15% lower grain yield comparing to the moderate irrigation. Under moderate irrigation, N3 treatment non-significantly increased the head diameter and biomass comparing to the N2 treatment by 9 and 16% respectively. Under water stress at V8, N3 treatment significantly increased the head diameter and biomass comparing to the N1 treatment by 12 and 29%, respectively. This result showed that choosing a suitable pattern of nitrogen top-dressing for attaining the maximum grain yield is more important when the plants are not suffering water stress or stress is occurred at early vegetative stage. But when the stress is occurred at early vegetative stage, then the pattern of nitrogen topdressing is not such important.

In order to study the effect of water deficit irrigations on grain yield and quality traits of three bread wheat cultivars (Triticum aestivum L.), an experiment was conducted at the Research Farm, Islamic Azad University Naragh Branch, in 2008-2010. A RCBD based split plot design with three replications used. Three irrigation regimes (ETC 100%, ETC 80% and ETC 60%) arranged to main plots, and three wheat cultivars (Ghods, Mahdavy and Roshan-backcross) arranged to sub-plots. Results showed that no significant differences were found between ETC 100% and ETC 80% treatments. ETC 60% treatment significantly reduced yield and yield components. However delay in irrigation significantly increased grain protein percentage. Cultivars were not significantly different in grain yield and protein percent. The results obtained here indicate that wheat may be irrigated ETC 80% not only may save about 20% in irrigation water with no significant loss in yield under conditions similar to this experiment, but also grain protein percent increase 1.7%.

In order to evaluate the effects of cultivar and planting pattern on soybean seed yield and yield components a split plot experimental design based on completely block design in three replications was carried out during spring in Bay-e-cola Agricultural Research Station with an elevation of 4 m over sea level and average rain fall of 514 mm. There were three cultivars namely: BP, JK and 032 as main plot and six planting patterns namely: 20×5, 20×10, 30×5, 30×10, 40×5, 40×10 cm2 as sub plot. The results obtained showed that maximum 100-seed weight in main stem and minimum number of seed per pod in main stem obtained in JK cultivars and maximum number of pod in main stem obtained in BP. It was observed that seed yield was not significantly affected among the cultivars. The maximum seed yield obtained for 40x10 cm2 pattern with 951.7g.2m2, coinciding with maximum number of pod per plant and seed per pod in main stem. It was also observed that maximum number of pod in main stem obtained at the interaction effects of BP cultivar at 40x10 cm2 where as the minimum number of empty pod in main stem obtained for BP as 30x5 cm2. Maximum seed yield observed at interaction effects of BP and 30x10 cm2.

This study was aimed at evaluating the effects of different planting dates (Heat stress) on the trend of Vejetative growth in addition to the yield of three rice Cultivare for one year in Shavoor regions in the north region of Khuzestan, as spilt plots in the form of fully random blocks in three repetitions. Main factor was the date of planting at three levels (26 May, 10 Jun, 26 Jun) and the second factor was in three levels including of Red Anbori varieties (long and short grains), and Champa. Results Analysis of variance indicated that there is a significant difference between different dates of planting and all properties; but to other of stem dry weight and fertility percentage, remnant characteristics there is not any significant difference in the interaction of both factors. Also maximum and minimum amount stem dry weight and height plant inverse grean yield, 1000-grain, fertility percentage, harvest index and leaf dry weight were related to the 1 and 3 dates. trend of all characteristics on 26 May, which had the maximum thermal stress at the reproductive stage, they reached the maximum growth in a shorter period of time. Among the Cultivares, Champa had the highest yield with an average of 3795/4 kg/ha. with attention Correlation coefficients maximum affirmative and significant grean yield was on the leaf dry weight (0.441*). Based on the results, it can be hoped that the yield of grain resulted from the increase of the growth and net photosynthesis in rice would be increased by focusing the breeding purposes on increasing the leaf weight.

Seed dormancy is one of the important problems among potato minitubers. It decreases the germination percentage by rotting the tubers. To overcome this problem an experiment was conducted at Agricultural Research Institute of Hamedan in 2012-2013. The experiments were carried out in factorial randomized complete design with two different treatments, the weight of minituber in three levels (1-3 g, 3-5 g and 5-10 g) and chemical treatments in seven levels (no treatment, 150 ppm gibberellic acid in 1 h, 300 ppm gibberellic acid in 1 h, 1% thiourea in 1 h, 0.5% thiourea in 1 h, 45 ml.m-3 carbon disulfide in 24 h, 45 ml.m-3 carbon disulfide in 48 h) with three replications per treatment. The Sante variety was tested for minituber size. After seed dormancy breakage, the days to germination, number of sprouts per minitubers and the sprout diameter were studied and then the mini-tubers were grown in pots. After tuber collection (harvesting), the number of tuber per plant, tuber weight and the total weight of all tubers were measured. We observed the highest stem diameter in 5 – 10 g tubers and the lowest sprout length in 1-3 g tubers. Also, among different breaking seed dormancy treatments, the 45 ml carbon disulfide in 48 h showed the significant increase in sprout length compare to the 45 ml carbon disulfide in 24 h which resulted the highest tuber size and weight. The gibberellic acid (300 ppm) treatment showed the highest number of tubers. The interaction study among treatments showed that, the 45 ml carbon disulfide in 48 h produced tubers with different size and they were high in weight compare to the others.