نشریه تولید گیاهان روغنی
سال یکم شماره 1 (بهار و تابستان 1393)

Impact of three water deficit treatments in vegetative, flowering and grain filling stages along with optimum irrigation as control were evaluated on grain yield and agronomic characteristics of 8 sunflower cultivars (Hysun 33, Hysun 25, Farrokh, Record, Aravirski, Lakumka, Master and SHF 81- 90) as a strip plot design with three replications in Khoy Agricultural and Natural Resources Research Station. Different water regimes had significant effect on growth period, plant height, stem and head diameter, seed yield and its component. Stem diameter, plant height and seed number per head were affected considerably by drought stress in vegetative stage, while head diameter by drought stress in flowering stage and growth period and seed weight by water deficit in seed filling stage. Water deficit in flowering and vegetative stages had the highest (38%) and lowest (25%) negative effect on grain yield, respectively, so flowering stage and vegetative stage established as the most sensitive and tolerant stages to water deficit, respectively. Farrokh hybrid with highest seed yield in different irrigation treatments (3686, 2856, 2256 and 2506 Kg/ha in control and water deficit in vegetative, flowering and grain filling stages, respectively) revealed as the most drought tolerant cultivator while Hysun33 lowest seed yield showed maximum drought sensitive.

In order to comparison of antioxidant enzymes and proline roles in drought tolerance of rapeseed, an experiment was conducted at the research field of Yazd Agricultural and Natural Resources Research Center in 2011-2012. In this study, three commercial rapeseed genotypes (GKH2005, Opera and Okapi) were examined for response to irrigation treatments such as nonstress conditions (control) and withholding irrigation from stem elongation, flowering and silique formation stages in four separate experiments based on randomized complete block (RCB) design. The results indicated that proline accumulation, activity of catalase and proxidase enzyme and lipid peroxidation index (content of malondealdehyde) were higher in drought stress treatments, but these amounts were different in three rapeseed genotypes. Maximum activity of antioxidant enzymes and low content of malondealdehyde was observed in GKH2005 compared with others, in drought stress conditions. Between these genotypes, GKH2005 produced the highest seed yield under non-stress conditions and withholding irrigation from stem elongation, flowering and silique formation stages as 3110, 1450, 1773 and 2510 kg.ha-1, respectively. These results showed that role of antioxidant enzymes on reduction of lipid peroxidation and increasing the drought tolerance is more than proline. Also, an effective antioxidant system along with lower malondealdehyde and high silique number per secondary branch had the greatest role to productivity maintenance of Rapeseed under drought stress conditions.

In order to study the effect of foliar application of zinc and iron on yield quantity and quality of canola (Brassica napus cv. Talaye), an experiment was conducted in Zarghan region of Fars in 2008- 2009 crop season..Treatments including concentration of zinc sulfate in three levels: (0, 2, 4 gr lit-1) and Iron sulfate in three levels: (0, 2, 4 gr lit-1). This experiment was arranged as factorial using randomized complete block design (RCB) in four replications. Iron and zinc solutions were sprayed twice (at first in stem elongation and then second in early flowering). Significant interaction between zinc and iron foliar application was observed for grain yield, seed protein percentage and oil yield. Maximum grain yield (4905.3 kg ha-1), seed protein percentage (37.7%) and oil yield 2124.5 kg ha- 1) was obtained from foliar application of combined zinc and iron at 4 g lit-1. Increasing of zinc from 0 to 4 gr lit-1 significantly increased 1000 seed weight (from 4.24 to 4.69 gr), number of seed per pod (from 19.12 to 22.88), seed oil percentage (from 38.67 to 43.17) and seed zinc concentration (from 33.28 to 22.07 mg kg-1). Increasing iron from 0 to 4 gr lit-1 significantly increased 1000 seed weight (from 4.24 to 4.64 gr) and seed iron concentration (from 64.29 to 79.18 mg kg-1). Ultimately, based on our results, the treatment of twice foliar application of zinc and iron sulfate and at 4 g lit-1 was suggested to get more quantity and quality of canola (Talaye) in Zarghan.

In order to investigate the effects of water deficit stress effects, different rates of nitrogen and plant density on remobilization, current photosynthesis and grain yield in oily sunflower var. Iroflor, an experiment was carried out in field Agriculture and Research center of West-Azerbaijan during 2011 and 2012 cropping seasons. The experimental was conducted as split-split-plot base on Randomized Complete Block Design (RCB) with 3 replications. The main factor was consisted irrigation treatment including optimum irrigation, moderate stress and sever stress which irrigation was done after depletion of 50%, 70% and 90% of available water, respectively. Three nitrogen levels of 100, 160 and 220 kg N haG1 were considered as sub plots and sub-sub plots consisted of three plant populations of 5.55, 6.66 and 8.33 plants m2. The results of combined analyzes showed that severe drought stress reduced the grain yield by 60% compared to the optimum irrigation condition. Comparison of twoyear- mean revealed that severe drought stress in compared with optimum irrigation dry matter remobilization rate decreased about 30 percent. Also, severe drought stress led to 35% reduction of current photosynthesis efficiency in compared with optimum irrigation. In each level of nitrogen fertilizer, increasing plant population led to increase contribution of remobilization but current photosynthesis contribution decreased. Therefore, due to reduction of current photosynthesis rate in severe drought stress condition, contribution of current photosynthesis decreased so that increasing of (contribution of, deleted) remobilization contribution prevented reduction of seed yield.

A field experiments was conducted at Sabzevar Agriculture & Natural Resources A field experiments was conducted to study the effect of zinc sulfate foliar application on yield and yield components of sunflower, Haysun-25 cultivar (Helianthus annuus L.) under drought stress at Sabzevar Agriculture & Natural Resources research center. This experiment was carried out (conducted, deleted) as split plot based on randomized complete block (RCB) design that main and subplot factors were drought stress levels [Non-stress, Moderate and High drought stress (6, 12 and 18 day’s irrigation interval, respectively] and foliar zinc applications (0, 5, 10 and 15‰), respectively. Foliar application of zinc was performed in 6 to 8 leaf stage of sunflower. Plant height, seeds per head, hollowness percentage seeds, 1000 seed weight, grain yield and biological yield were significantly affected by drought stress. Severe drought stress decreased plant height, seeds per head, 1000 seed weight and economic yield and increased percentage of empty seeds. The highest yield and yield components were related to foliar application with 15‰ concentration of zinc sulfate and the lowest one was related to the control. However, yield response to zinc sulfate foliar application was more in non-stress condition, but zinc sulfate with 15‰ led to decrease of negative effects of drought stress. Overall, the highest yield was obtained by spraying with concentration of 15‰ zinc sulfate and non-stress condition.

In order to the evaluate the effect of planting dates on phenological traits, plant height, pods per plant and seed yield of rapeseed spring varieties, a split-split plot experiment based on randomized complete block design with four replications was conducted during 2 years at Agriculture Research Station of Baykola, Mazandaran, Iran. Treatments were planting dates (September 29, October 9, October 19, October 29 and November 8) as main plot and sub-plots were three cultivars (Hyola401, Option500 and RGS003. All the traits were affected by planting date and variety. The mean values of seed yield of Hyola401, Option500 and RG 003 were 3274, 2898 and 3040 kg ha-1, respectively and Option500 and RGS003 had not statistically significant difference. Non significant interaction effects of planting dates and varieties for seed yield indicated that yield reduction of the varieties in late planting dates had similar trend and Hyola401 and Option500 had the most and the least seed yield, respectively. Seed yield reduction at late planting date was related to insufficient vegetative growth before flowering stage. Significant positive correlation between plant height and number of pods per plant was the main reason that in late planting date reduction of plant height imposed reduction of pods per plant and finally seed yield was decreased.