فصلنامه علوم زراعی ایران
سال شانزدهم شماره 4 (پیاپی 64، زمستان 1393)

The objective of this experiment was to evaluate technological properties of two sugar beet cultivars (HI1059 and Palma) under conditions of bolted and non-bolted plants. The experimental design was randomized complete block design (RCBD) with four replications and was carried outat Safiabad Research Center, Dezful, Iran, in 2011-2012 growing seasons. At harvest, bolted and non-bolted plants of each plot were separated. Sugar content, concentration of impurities (potassium, sodium and amino-nitrogen), molasses sugar, root yield, sugar yield, cutting resistance of rootand vascular tissue to parenchyma tissue ratio traits were measured using standard methods. In general, mean bolting (%) in HI1059 and Palma cultivars were 33% and 51, respectively. Analysis of variance showed that the experimental treatments effect for yield and quality traits of sugar beet was not significant. Results of group comparison between bolted and non-boltedplants in both varieties showed that sugar content reduced from 16.1 to 15.6% on HI1059 variety and from 16.4 to 15.9% in Palma cultivar, respectively, due to bolting. Despite the slight decrease in root yield (5%), and sugar yield (7%) in bolted plants, these reductions were not significant. Similarly, despite a slight increase in concentration of impurities, molasses sugar, energy for cutting root andvascular tissue to parenchyma tissue ratio in bolted plants, differences were not-significant. Although bolting appeared about one month before harvesting in the two sugar beet cultivars, but it had no significant effect on yield and quality of sugar beet. However, bolting causes some disturbs sugar beet harvesting and creates physical and chemical problems in the process of sugar extraction in the factory. Further research of variety trails over growing seasons may provide more knowledge regarding theeffect of bolting on yield and technical quality of sugar beet.

Nitrogen management under water limitation condition is an important factor to obtain high grain yield of maize (Zea mays L.). To study the effects of irrigation and different nitrogen fertilizer levels on dry matter remobilization, grain yield, chlorophyll and carotenoid contents of maize cv. SC 260, a field experiment was conducted in Research Station of Islamic Azad University of Shiraz, Iran in 2012 and 2013. The experimental design was split-plot arrangement in randomized complete block design with four replications. The main plots consisted of four soil moisture depletion (MD): MD1 (20% MD), MD2 (40% MD), MD3 60% MD) and MD4 (80%MD). Four rates of nitrogen fertilizer application: 150, 200, 250 and 300 kg.ha-1 were randomized in subplots. Results showed that grain yield, biological yield, chlorophyll index, chlorophyll a, b were significantly higher in MD1 than the other treatments. However, the highest contribution of stem and leaf dry matter remobilization to grain and carotenoid were obtained in MD4 and 300 kg N ha-1and the lowest in the MD1 treatment and 150 kg N ha-1. In general, nitrogen application increased all traits of maize; however, there were no significant difference between 250 and 300 kg N ha-1.Nitrogen fertilizer relieved the negative effects of water scarcity and 250kg N ha-1at all levels of soil moisture had the greatest effect. Nitrogen application at each moisture level increased the proportion of drymatter remobilization to grain yield, and the greatest contribution of remobilization was obtained at the highest rates of N fertilizer with the highest moisture content. Results showed that increasing nitrogen application enhanced the contribution of dry matter remobilization to grain under water deficit conditions.

To study the effect of IAA and Kinetin phytohormones on the improvement of drought tolerance in rice seedlings (Oryza sativa L.), an experiment was carried out as factorial experiment with three factors based in completely randomized design with three replications in Agricultural Science Faculty, University of Guilan, Rasht, Iran, in 2013. The experimental factors included: 1: four rice genotypes; Gharib, Khazar, Sepidrood and Upland (IR 83750-131-1), 2: drought stress condition; control (non-stress) and drought stress from 1 to 4 of Vergara coding system and 3: hormone in three levels; control (without hormone application), IAA (5×10-5 M) and Kinetin (5×10-5 M) as foliar application. Tiller No., day to leaf rolling, leaf temperature, relative water content, electrolyte leakage, SPAD value and chlorophyll fluorescence parameters were measured. Analysis of variance indicated that all studied traits were significantly affected by all experimental factors and their interactions. Sepidrood cultivar had the highest relative water content RWC in drought condition (46.3%). The lowest relative water content (34.5%) belonged to cv. Gharib in drought stress condition. Application of IAA in both control and drought stress conditions increased RWC to 92.4% and 43.7%, respectively. In non-stress condition, Upland cultivar had the highest relative chlorophyll content (47.1%). The lowest SPAD value (30.6) belonged to Gharib in drought stress condition. IAA and Kinetin hormones increased the leaf relative chlorophyll content in Gharib cultivar to 18% and 13.7%, respectively. Drought stress without hormone application increased electrolyte leakage (32.1%). The lowest electrolyte leakage 16.3%) was observed in Sepidrood cultivar in non-stress condition. The highest photosystem II quantum efficiency (Fv/Fm) was 0.81 which belonged to Khazar cultivar in non-stress condition and IAA application. Results of this experiment indicated that the application of IAA and Kinetin hormones improved the drought tolerance related traits in rice seedlings under drought stress conditions. IAA had more effective role than Kinetin in improving drought stress tolerance in rice seedlings. Also results indicated that the Upland and Sepidrood rice cultivars were more tolerant than Gharib and Khazar. Generally, upland cultivar was more responsive to IAA application under drought stress condition.

To study the effect of iron application methods on the yield, yield components, oil seed and fatty acids profile of a spring safflower cultivar Goldasht (IL-111) under deficit irrigation conditions, a field experiment was conducted in 2011 and 2012 in research field of the Faculty of Agriculture of Shahed University, Tehran, Iran. The experiment was set up as split-plot arrangement in randomized complete block design with four replications. The main plots consisted of two levels of irrigation treatments: 1: full irrigation (I1: irrigation at 50% soil moisture depletion relative to field capacity) and 2: deficit irrigation at the flowering stage (I2: irrigation at75% soil moisture depletion relative to field capacity). The subplots consisted of eight levels of Fe- EDDHA, half of which were soil applications (S1:0, S2:50, S3: 100 and S4:150 kg.ha-1) and the remaining half were foliar applications (F1:0, F2:1, F3:2 and F4:3 g.l-1). In general, grain yield and the oil content were affected by the interaction of irrigation ×Fe. Results showed that with full irrigation and an increase in application of Fe, the grain yield and grain oil content increased significantly. With a decrease in soil moisture to 75% of the field capacity, the highest grain yield and grain oil content were obtained with the F2 treatment, i.e., 1 g.l-1. Grain yield and oil content were 2535and 1042 kg.ha-1, respectively, in 2011 and 3176 and 1440 kg.ha-1, respectively, in 2012. Mean comparisons indicated that, in years, total biomass, harvest index and oil content were significantly affected by the application of Fe to the soil under water stressed conditions. The foliar application of Fe resulted in a significant increase in the amount of linoleic acid and decreased palmitic acid under a water deficit, while the soil application of Fe had the greatest effect on oleic and stearic acids. Grain yield and oil content in Fe at 1 g.l-1 treatment increased by 53.7% and 162.2%, in 2011 and 29.2% and 73.5%, in 2012, respectively, in comparison with treatment S4 (150 kg.ha-1). It can be concluded that the foliar application method under deficit irrigation condition can increase grain yield and improve the oil quality of safflower cv. Goldasht.

To evaluate yield stability of 40 bread wheat genotypes, six randomized complete block design with three replications were conducted in three years during 2009 to 2011 in Kerman University, Kerman, Iran, under normal and drought stress conditions. Combine analysis of variance showed that environment, genotype and genotype by environment interaction were highly significant. Analysis of variance of additive main effects and multiplicative interaction (AMMI) showed that five IPCA were highly significant and the sixth IPCA was considered as noise. Five significant IPCAs were used simultaneously using AMMI stability value (ASV). Based on ASV Hirmand, Kavir and Omid, and based on superiority statistics Alvand, Alamoot and Kavir were the most stable cultivars. Kavir had high yield and introduced as the most stable genotype in this study. Shiraz cultivar was the most unstable genotype. Considering average over all environments, Shiraz cultivar had the highest yield. Based on the results of this experiment, Kavir and Shiraz may be considered as parents in breeding program to take advantage of yield potential and stability in the progenies.

Twenty eight crosses of four temperate maize testers (MO17, K18, K166B and A679) with seven lines originated from CIMMYT germplasm were evaluated using a randomized complete block design with three replications, at seven locations (Karaj, Shiraz, Dezful, Jiroft, Moghan, Gorgan and Kermanshah), Iran, in 2012. In 2013, number of lines were increased to 13, and 52 crosses were obtained with the same testers as in 2012. Hybrids No. 28 (XT02 ×K166B), 10 and No. 23 had 10.160, 9.867 and 9.822 t.ha-1 grain yield, respectively, that revealed to be of high yield potential hybrids. Combined analysis of Line ×Tester showed no significant differences between lines and testers, but significant line × tester interaction effect was observed. Significant general combining ability (GCA) effects were obtained for the four testers, but none of the lines showed significant GCA. Results showed the possibility of germplasm enhancement in temperate maize program, using CIMMYT germplasm (tropical and subtropical), especially those sources produced under similar conditions as Iran (such as CIMMYT program in China). This experiment revealed that crossing these germplasm with temperate maize germplasm prior to selfing, has no significant effect on derived lines. Using more sources, as well as testers, from each group is necessary to facilitate the success in development of adapted maize germplasm.