مجله تولید گیاهان زراعی
سال ششم شماره 1 (بهار 1392)

In order to investigate the effect of phosphorus fertilizer and spraying Fe chellat in micronutrients absorption rate, rate of proline and soluble carbohydrates in bread wheat and some of its ancestral species in dryland condition, a factorial experiment was conducted with three factors consist of: P fertilizer (in two levels), spraying Fe chellat (in two levels) and different species of wheat (sardari cultivar, Triticum boeoticum, Aegilops speltoides,Triticum diccocoides,Aegilops tauschii) in the form of randomized complete blocks design with three replications in research farm of Agricultural faculty of Ilam University. Results showed that micronutrients absorption rate in different species of wheat was different significantly. Triticum diccocoides had the most rate of phosphorus and cupper absorption, Aegilops speltoides had the most of Mn absorption efficiency and Triticum boiticum had the most rate of Fe absorption. Results showed that in flowering stage application of P fertilizer caused increase in proline and soluble carbohydrates. Sardari cultivar and Aegilops tauschii had the most amount of proline and carbohydrate content. Interaction of P fertilizer factor in different species of wheat was significant on proline and soluble carbohydrates rate. Application of phosphorus, increased proline and soluble carbohydrates rate in crop species of wheat and Aegilops tauschii more than other species.

In order to evaluate the effect of Rimsulfuron, EPTC (Eradican), oxadiargyl, metribuzin and Metribuzin herbicides for controling of Lambsquarter (Chenopodium album) and prostrate pigweed (Amaranthus retroflexus), an experiment was conducted at the Mohaghegh Ardabili University green house in 2008. A dose-response assay was conducted based on completely randomized design with four replications. The potato cultivar was Agria (common cultivar in Ardabil). Herbicides were used in six doses included reduced and overdoses rather than recommended doses. Common lambsquarter and prostrate pigweed were sprayed during the 2-4 leaves stage and potato was in 15-20 cm. Results showed that the most effective herbicides for weed control were Metribuzin, Oxadiargyl, Rimsulfuron and EPTC, respectively. Also the least herbicides damage for potato was in Rimsulfuron, EPTC, Oxadiargyl and Metribuzin, respectively.

The aim of this experiment was the study of dry matter and nitrogen (N) accumulation, remobilization and harvest index in different wheat cultivars. Five bread wheat cultivars (Darya, Kuhdasht, Shiroudi, Tajan and Zagros) and two durum wheat cultivars (Arya and Dena) were studied under optimum growth conditions during 2008-2009 at research field of Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran. Experimental design was a randomized complete block design with four replications. Results indicated that average total dry matter remobilization was 23.8%,which was affected by cultivar. Furthermore, results indicated that 57% of N remobilization from vegetative organs before anthesis and 11% from N uptake and/or N remobilization after anthesis contributed for grain growth. Therefore, majority of grain N supplied by remobilization of N from vegetative organs during seed filling period. Among organs, the leaves had the highest N remobilization (nearly 72%). Results indicated that leaves and stems N concentration decreased 57 and 54%, respectively, at the time of physiological maturity as compared with anthesis. N harvest index was 72.2% which it was not affected by cultivar. Meanwhile, N concentration in senesced leaves and stems along with grains were 1.04, 0.43 and 2.13%, respectively. The amount of harvest index was 44.1%, and it was not affected by the cultivar. There was a positive and significant correlation between the amount of N uptake by vegetative tissues, especially in leaves, with grain N and grain yield. The parameters obtained in this study can be used in wheat N modeling.

In order to evaluate competition among some weed species and canola, a field experiment was done in Astan Ghods Razavi's field of Mashhad in 2007-2008. Thirty quadrates (50×50 cm) were used in two times (stem and flower production) to measure the canola dry weight, leaf area index and canola and weeds density with destruction, and thirty similar quadrates were used for counting weed species and identification without destruction. In order to estimate dry weight and leaf area of non-destructive quadrates; a nonlinear hyperbolic function has been fitted between leaf area or dry weight of weed and canola (species exist in destructive quadrates) as a dependent variant and their number as an independent variant. For comparison of competition status and estimation of inter and intra specific competition coefficient for each species, multi linear regression function between the early season relative leaf area as an independent variant and the latter season of individual plant weight of weed and canola as a dependent variant has been fitted. Regression results showed that reversed weed dry weight and relative leaf area have a proper fitting (r2=0.87) for estimation of yield reduction and competition coefficients. In this research in spite of present of Fumitory (Fumaria officinalis L.), Knot weed (Polygonum aviculare L.) and Malcolm stock (Malcolmia Africana L.) only wild oat (Avena ludoviciana L.) inhibited canola growth. The positive effect of other weed species on canola growth was probably due to their inhibitive effect on wild oat as a main competitor for canola.

In order to evaluate forage quality in intercropping, two field experiments were carried out based on randomized complete block design with three replications at the Agricultural Research Station, Faculty of Agriculture, University of Tabriz, Iran, in 2005-2006 and 2006-2007 growing seasons. Two maize (Zea mays L.) hybrids (SC704, SC301), vetch (Vicia villosa), bitter vetch (Vicia ervilia), berseem clover (Trifolium alexandrinum L.) and common bean (Phaseolus vulgaris) as sole crops and intercrops of maize hybrids with each of the legumes as an additive method were used. Results showed that forage quality characteristics such as protein yield, neutral detergent fiber (NDF), acid detergent fiber (ADF), total digestible nutrients (TDN) and dry matter intake (DMI) were affected by intercropping. The highest crude protein yield (CPY) was achieved with maize hybrid 704-vetch (1937.19 kg.ha-1) and maize hybrid 301-vetch (2180.95 kg.ha-1) intercrops and the lowest CP per ha was observed at monocultures of maize hybrid 704 (714.97 kg.ha-1) and maize hybrid 301 (762.308 kg.ha-1). Also mixture maize hybrid 301 with bean, vetch and bitter vetch showed a lower NDF and ADF content than the other intercrops. In conclusion as NDF and ADF percent decreased in intercrops, but TDN and DMI increased. Based on this study, mixture of maize hybrid 301 with vetch and common bean is considered as prime forage.

In this study the effects of post-harvest application of Rindite in various concentrations (0, 0.2, 0.4 and 0.6 ml L-1) and with different exposure duration (24, 48 and 72 h) on breaking of dormancy and sprouting of potato (Solanum tuberosum L., cv. Marfona) minitubers of two ages (freshly harvested and one week after harvest) was investigated. In comparison with the control minitubers, Rindite treated minitubers showed significantly shorter dormancy, especially when minitubers were treated one week after harvest. Three-way interactions effect of concentration, duration and minitubers age on the minituber sprouting were statistically significant and application of Rindite by fumigation with 0.2 ml L-1 for 48 h or 0.4 ml L-1 for 24 h effectively reduced the dormancy period of one week old minitubers. The number of sprouts per minituber was significantly enhanced by treating minitubers with Rindite where compared with the untreated control minitubers, however, there were no differences among concentrations or exposure durations. The length of sprouts per minituber was significantly increased by treating minitubers with Rindite. There were also strong interaction between concentration and duration, in concentration of 0.2 ml L-1, the length of sprout showed a positive correlation with exposure duration, but in 0.6 ml L-1, this correlation was negative. In concentration of 0.4 ml L-1, with increase in duration until 48 h the sprout length increased, but further increase in duration led to decrease in sprout length. When longer duration was accompanied with higher concentration, treatment with Rindite led to rotting of minitubers.

In the first phase of this research, adaptability of winter rapeseed (Brassica napus L.) varieties was investigated to select high yielding rapeseed cultivars. Accordingly, two field experiments were performed in a randomized complete block design with 15 winter rapeseed varieties in three replications from 2006 to 2008 cropping seasons at experimental field of Agricultural and Natural Resources Research Center of Markazi Province, in Arak, Iran. Results showed that Licord, Modena and Okapi varieties had superiority to other cultivars, respectively. At the second phase of this research, also, two field experiments were carried out from 2008 to 2010 cropping seasons at the same site, in order to evaluate the effects of nitrogen sources on seed yield and content of macro elements in seed of selected high yielding rapeseed varieties. Experimental design was a factorial arrangement based on randomized complete block with three replications. Three rapeseed varieties (V1=Okapi, V2=Modena and V3=Licord) and three sources of nitrogen based on 150 kgN/ha (N1=Compost of Azolla, N2=50% Compost of Azolla plus 50% Urea and N3=Urea) comprised the experimental factors. Results showed that Licord variety had the highest seed yield and seed content of Sulphur. Integrated nutrition system showed superiority to other treatments for seed yield and seed content of macro nutrients such as nitrogen, phosphorus and Sulphur. But, the greatest seed potassium content was observed in N1 treatment. Results showed that integrated application of nitrogen sources increased yield and seed macro nutrients content.

In order to evaluate of drought stress and foliar application of zinc and iron on two annual medics species, a field experiment was carried out with split factorial based on randomized complete block design in three replications with treatments of foliar application (Controlled, Fe, Zn and Fe + Zn) with 5 gr/liter concentration in vegetative stage and cut off irrigation from (50% flowering, lower pod maturity, 10 days before starting of flowering and control treatment). Drought stress was considered as a main plot and combination of factorial between foliar application and two annual medics species as a subplot.The results showed that leaf to stem ratio in scutellata (1.82) was more than polymorpha (1.43). Drought stress reduced 27% and 33% forage fresh weight and pod yield in comparison with control, respectively. The number of pods per plant increased 17.6 and 27.6 percent incomparison with control in iron and iron + zinc treatments, respectively. Zinc application treatment in drought stress control increased the number of pod per plant in scutellata and polymorpha species 181% and 277%, respectively in copmarison with control treatment. The results showed that seed per pod increased 58% in Fe + Zn treatment in polymorpha species but those increased 40-70% in total foliar application to control in drought stress control. The nitrogen fixation in the thirth level of drought stress was reduced 51% in scutellata and polymorpha, respectivelly compared to control. Iron+Zinc application increased protein forage 23.3% and 21.7% in scutellata and polymorpha in fourth level of drought stress, respectively.

In order to determine the practical method to predict economic production of wheat in competition with feral rye by using regression models, a factorial experiment was carried out based on randomized complete block design with three replications in Dargaz, Iran. Experimental factors were included wheat cultivars (Sayson, Alvand, Chamran and Sepahan) and feral rye densities (0, 20, 40, 60 and 80 plants m-2). The results showed that increasing feral rye density, reduced biological and grain yield of wheat cultivars. In contrast, biological yield, grain yield, spike number per unit area of weed and infestation percentage of weed seed was increased. The lowest and the highest initial slope (Parameter I) of grain and biological yield loss was obtained in Sepahan and Chamran cv., respectively. At all density levels, grain yield of Alvand cv was superior to other cultivars. The highest amount of biological yield, grain yield, spike number of weed and percentage of crop infestation was obtained in Chamran cv. In the range of acceptable infestation level of wheat to weed seed (0-7 Percent), the lowest and highest feral rye density that was led to same infestation, were estimated in Chamran and Alvand cv., respectively. The highest production and gross profit was obtained in both Alvand and Chamran cultivars. Generally, Alvand cv. in addition to the negative effect on weed production, had a high gross profit. So in experimetal region, mentioned cultivar is recommended for planting in feral rye infested fields

Ranking the viewpoint of experts and farmers is an approach to determine the factors causing the yield gap. For this purpose, two different questionnaire types but with same questions designed for both agricultural specialists and farmers. After answering, the questionnaires of agricultural experts and farmers were analyzed through AHP and entropy techniques, respectively. Both techniques determined and ranked the importance of factors affecting on wheat yield gap based on attributing relative weights to factors with respect to comments provided in the questionnaires. Analysis of different experts viewpoints through AHP method showed that inappropriate management of irrigation, lack of good varieties grown genetically, and inappropriate use of basic, broadcast and micro fertilizers are the most important factors causing yield gap in the studied area. The results of analysis of the viewpoints of farmers using entropy technique showed that the inappropriate amount of seed at planting, inappropriate use of micro fertilizer, inappropriate planting depth, lack of good cultivars grown genetically and seed loss at harvest are the most important factors causing wheat yield gap, respectively. With respect to inconsistency in the viewpoints of these two groups, it was recommended that it should be made a strong relationship between agricultural experts and farmers to transfer expert's viewpoints to farmers for decreasing yield gap.

In order to determine the best traits related to indirect increasing of grain yield, five wheat genotypes (Zagros, Tajan, Durum cul., Kohdasht and N-81-18 line) were evaluated by using randomized complete block design (RCBD) with 4 replications in research field of Gorgan University of Agricultural Sciences and Natural Recourses. The studied traits included leaf area index (LAI), crop growth rate (CGR), relative growth rate (RGR), net assimilation rate (NAR), number of tiller, number of spike per plant, number of grain per spike, spike weight, grain weight, biological yield, harvest index and grain yield. The most grain yield was belonged to N-81-18 line. This line showed most number of grain per spike and spike weight in comparison with other genotypes. The results showed, there was significant correlation between grain yield and harvest index in all genotypes. The results of path analysis showed spike weight had the most direct effect on grain yield, in most genotype. Among of growth indices LAI had most negative direct effect, since correlation between leaf area and grain yield was significantly positive; therefore, the last correlation should be via indirect effect.