فصلنامه اکوفیزیولوژی گیاهان زراعی
پیاپی 53 (بهار 1399)

Chickpea as one of the most promissing crop under dry farming in Razan, Hamadan where it is often confronted with terminal drought of growing season. Finding strategies to reduce the effects of terminal droughts of chickpea under dryland conditions in this area would be very beneficial. To evaluate the effects of foliar application of glycine betaine (GB) and salicylic acid (SA) on yield and yield components of two chickpea cultivars under rainfed condition, a factorial experiment based on randomized complete block design with three replications was conducted at Razan town of Hamedan province in 2017- 2018 year. In this experiment, treatments were the use of distilled water as control, three levels of glycine betaine (200, 400 and 600 mM) and three levels of salicylic acid (250, 500 and 750 µM) on two cultivars of chickpea (Hashem and Saral). The results showed that foliar applications of plants with GB and SA resulted in significant effect on all traits under study, except number of seed in pod. The highest of seed yield was observed in Hashem (168.05 g.m2) and Saral (178.55 g.m2) cultivars with foliar application of 600 mM glycine betaine. The treatment of 600 mM of glycine betaine increased seed yield of Hashem and Saral cultivars by 17.6 and 18.5 percents, respectively. There were significant differences between the two cultivars under study. Maximum of number of seed per plant, seed yield, biological yield and harvest index were belonged to Saral cultivar, while plant height, weight of 100 seed and percent of protein seed observed in Hashem cultivur. According to the results of this study, it can be concluded that the application of glycine betaine on yield and yield components of chickpea under rainfed conditions was more effective than using salicylic acid. It can be said that foliar application of chickpea with GB and SA would improve the performance of chickpea cultivars and rainfed conditions. Futher studies are sudgested to substantiate the results.

Drought is one of the most important growth and yield limiting factors of crop plants in many parts of the world. To investigate the effects of drought stress and seaweed extract and salicylic acid on some photosynthetic and photochemical traits of white bean plant, a split-factorial experiment, based on randomized complete block design with three replications was conducted in 2016-2017 growing season. The experiment was performed at two different locations: Islamabad and Khorramabad. Main factor consisted of three levels of irrigation (irrigation after 60 mm, 90 mm and 120 mm of accumulated evapotranspiration of class A pan evaporation and sub-plots of 8 different levels of salicylic acidapplication (0.5 molar), no application of salicylic acid, 4 levels of seaweed extracts applications 0, 50, 100 and 150 grams. Results of this study showed that drought stress decreased the rate of photosynthesis and chlorophyll content, but the salicylic acid increased both the rate of photosynthesis and chlorophyll content. Drought stress also increased proline content, ion leakage from the membrane and antioxidant enzyme activities such as catalase, ascorbate peroxidase and superoxide dismutase and reduced the grain yield. Application of salicylic acid increased the activity of antioxidant enzymes, but the response to salicylic acid was not similar in various levels of seaweed. The lowest grain yield was obtained from  irrigation after 120 mm evaporation and without application of seaweed. Highest grain yield was obtained from irrigation after 60 mm evaporation and 150 g. seaweed treatment. Application of seaweed enhanced the grain yield production. Application of salicylic acid also, increased grain yield by 4.5%. According to the results of this study, it seems that application of salicylic acid and seaweed may reduce some negative effects of drought stress.

Drought tolerance of 18 advanced lines durum wheat were evaluated in a randomized complete block design with four replications under dryland and complementary irrigation conditions in GachsaranAgriculturalResearchCenter at 2016-2017. In this study, traits like days to spike formation, days to maturity, plant height, peduncle length, spike length, 1000 seed weight, seed yield, spike number, spike number per m2, canopy temperature reduction of two stages of spike and seed filling, rate of greenness at two stages of spike and grain filling, were measured. Analysis of variance showed that there were significant differences among lines under study for days to spike formation, plant height, peduncle length, spike length, 1000 seed weight, seed yield, crop score, number of seeds per spike, temperature reductions of canopy at two spike stages seed and greenery content in two stages of spike and grain filling were significantly different. Mean comparisons showed that lines 4, 9, 13, 15, 16 and 17 were better than other lines in most traits. Evaluation of sensitive and tolerant lines according to tolerance index (Ti) showed that lines 1, 2, 4, 6, 9, 15 and 17, had high Ti index in most traits, were tolerant. Selection for superior lines, based on SIIG and selection of ideal genotype (SIIG) index, were performed. The results of variance analysis of traits based on Ti index showed that difference among lines in terms of 1000 seed weight, reduction of canopy temperature at grain filling stage, seed yield, grain filling period, chlorophyll content at both clustering and grain filling stage, days to reach and number of days to clustering were significant at 1% probability level. Lines 4, 5, 9 and 15 were the highest values of this index and were suitable for growing under dryland conditions. Lines 7, 8, 10 and 14 having lowest value of the SIIG index were sensitive to rainfed condition. The results of this ranking are similar to the results of cluster decomposition based on Ti index.

Selenium due to its physiological and anti-oxidative properties is considered to be essential micronutrient for humans, animals and plants. The positive effects of selenium on reduction of various environmental stresses in plants is, however, still unclear and need to be explored. In this study, the effect of selenium on increasing drought tolerance of yellow landrace onions in Isfahan was investigated by factorial experiment in a completely randomized design under greenhouse conditions. Treatments were drought stress at three levels (0, 50 and 75% of field capacity) and levels of selenium at three levels (0, 5 and 10 mg.L-1 sodium selenate). Foliar application of selenium was performed in two plant growth stages. The first foliar application at the onset of stress (onion production stage) and the second application was carried out two weeks after the onset of stress (onion development stage). Increasing selenium concentrations, under all levels of drought, traits like plant height (62.66 cm), leaf number (11.66), fresh weight (36.82 g) and dry weight of bulb (4.66 g) were increased. In contrast to drought stress, selenium concentrations increased onion physiological properties (total phenol, flavonoid, total soluble sugar, relative leaf water content and stomatal conductance). Increased onion growth under drought stress is attributed to the antioxidant property of selenium. Because, selenium acts as an oxidant at high concentrations it decreased growth. Selenium at 10 mg.L-1 did not have any detrimental effect on onions. It increased the growth of bulb and seedling onion. These results suggest that selenium application may improve antioxidantal defense system of onions under drought stress conditions. Thus, its use may be recommended under arid and semiarid regions.

Over use of water and unnecessary limitation irrigation water, both affects economic production of corn. Therefore, it is necessary to use different irrigation regimes in order to determine the most suitable irrigation interval with minimum effect on yield. To study the effect of different irrigation regimes on forage and grain yield of three varieties of maize, an experiment was carried out at the Research Center of Khoy, a province of west Azarbaijan, in 2008. The experiment was carried out with four replications in an form of split plot based on randomized complete block design. The main plot consisted of four levels of irrigation intervals (I1, I2, I3 and I4) of corn plots, irrigated after 60, 90, 120 and 150 (mm) evapotranspiration pan. Subplots consisted of three varieties of corn (SC704, Maxima524, Jeta600). In this experiment, different features of maize varieties were analyzed and measured at milk stage (R3) as forage. Results showed that by increasing irrigation cycle and as a result decreasing water using in four levels of irrigation, traits like forage yield, ear weight, plant height, stem and leaf weight, ear leaf area and relative water content have decrease in treatment according to decrease in water used. Among three the varieties under study, Maxima524 due to lower growing period as compared to the other two varieties, used low water volumes while yielded equal to the other two varieties. Overall, results showed that Maxima524 based on irrigation after 90 mm evaporation is found to be low water user against optimal performance.

This experiment was conducted to study yield increase of forage sorghum by its intercropping with forage legumes and weed control. This study was carried out in a factorial experiment based on a randomized complete block design with 3 replications at the Research Station of University of Zanjan in 2015. In this experiment, a different proportatios of sorghum with forage legumes including pure culture of sorghum plants, lathyrus and hairy vetch, increased percent of sorghum by 33%, 66% and 100% of hairy vetch and lathyrus, and different weed control management, including full weed control during season, single weed control and no weeds control, were examined. The results showed that the highest and lowest fresh and dry yields of sorghum were obtained in intercropping of sorghum with 33% vetch and 100% lathyrus, respectively. The highest chlorophyll content and leaf area belonged to sole cropping of sorghum and full weed control. The highest height of sorghum and cover crops was observed in 100% sorghum+ 100% lathyrus and weed-infested. On the other hand, in the sole culture of vetch and lathyrus and full weed control treat, the cover crops had the highest dry weights. The results of this experiment also showed that the highest dry weights and density of weeds were obtained under sole culture and weed-infested condition. As a result, it can be said that by selecting the appropriate intercropping ratios and forage legumes, we can control weed population to a large extent also improve the quantitative yield of sorghum forage.

Using an effective management method can reduce weed contamination of main crop plants. To investigate the effect of cover crops on weed control and potato yield an experiment was conducted based on randomized complete block design with three replications at Research Field of University of Mohaghegh Ardabili in autumn of 2017 and spring of 2018. Experimental treatments consisted of oat (Avena sativa L.), white radish (Raphanus sativus L.) and double blend cultivation with 50% seed ratio and control treatment at 2017 (autumn) and subsequent potato planting in 2018 (spring). The results showed that the cover crops had a significant effect on lambsquarter (Chenopodium album L.), Amaranthus retroflexus L. and total weeds biomass in the main crop (potato) but not on other weeds (including Cirsium arvense L.). The highest biomass (466.1 g.m-2) among the cover crops and the lowest winter weeds biomass were related to white radish monoculture. The lowest weed biomass of amaranthus and total weeds biomass were obtained from white radish, and the lowest biomass of lambsquarter was obtained from white radish+oat. White radish was able to control 45.7% of total weed biomasses compared to control treatment. The highest yield and average tuber weight, marketable percentage and the lowest small potato tubers were obtained by white radish. White radish had the highest yield (3.74 kg.m-2), which increased potato yield by 46.3%, as compared to the control treatment. The highest number of potato tubers was obtained from oat as cover crop. Growing white radish along with oats also had the highest percentage of oversize tubers. In general, white radish can be a good choice to be used for winter cover crop before potato planting, either as a intercropping with Poaceae species or as a monoculture.

To evaluate the effect of time and rates of imazethapyr application on weed control of bean field an experiment was conducted in Agricultural Research Station of Lorestan University based on the randomized complete block design (RCBD) with three replications in 2015-2016. In this experiment, the effects of pre planting, pre emergence and post emergence applications of imazethapyr with different rates (0.25, 0.5, 0.75 and 1 lit.ha-1) and pre planting imazethapyr mixed with soil (1 lit.ha-1) plus post emergence with weed control in two levels (control and non- control) was studied. The most important weed species in the experimental site were safflower (Carthamus oxyacantha), catchweed bedstraw (Galium tricornutum), wild mustard (Sinapis arvensis), cow cockle (Vaccaria grandiflora), chickweed (Conringia orientalis). Weed density in weedy control condition was estimated to be 133 plants.m-2. The results showed the maximum percentage of weed dry weight loss, as compared to not controlling weed due to imazetapir post-treatment application of 0.75 and 1 L.ha-1, was 86.95%. Also highest average root length (12.46 cm), root dry weight (95 g), number of branches (5.33), number of seeds per pod (9.3) and seed yield were observed in hand weeding. The highest plant height (88.33 cm) belonged to weed control treatment, the highest LAI (2.59) in herbicide usage, in pre planting (0.25 lit.ha-1), the highest average number of pod per plant (10 pod), number of pod per m-2 (100 pod) and biological yield (33367.1 kg.ha-1) resulted from pre emergence herbicide application (0.5 lit.ha-1). The highest of 100 seed weight (109.6 g) for pre planting herbicide application (1 lit.ha-1) plus herbicide post emergence application (1 lit.ha-1) was seen. The results also showed that, after hand weeding, the best concentration of imazethapyr pre emergence application (0.5 lit.ha-1) that it could decrease weed density by 99% as compared to not controlling weed. This treatment (imazethapyr pre emergence application (0.5 lit.ha-1) was the best treatment. Higher concentrations of herbicides also decreased bean yield because of burning, reduction in leaf area and photosynthesis.