نشریه پژوهش های کاربردی زراعی
پیاپی 137 (زمستان 1401)

Drought is one of the major environmental stress induced by global climate change that adversely affects the growth and development of plants and causes significant yield losses in the oil seed crop, safflower. Drought stress adversely impacts growth and productivity with various physiological and biochemical processes such as stomatal conductance, photosynthesis, chlorophyll content, carbohydrate metabolism, lipid peroxidation, and antioxidant defense system. As, the water resources used for irrigated agriculture are decreasing in many agricultural regions of the world, therefore, irrigation management under water scarcity is increasingly important. Various deficit irrigation management strategies have been developed in different agroclimatic regions to improve crop performance under water deficit conditions. However, It is very important to develop crop management strategies that make plants suited for stressful environmental conditions

In order to study of deficit irrigation management on physiological and biochemical traits of two safflower cultivars, a field experiment was carried out in a split-plot arrangement in a randomized complete block design with three replications. The experimental site (32° 22' N, 48° 07' E), was located at Shahid Chamran University of Ahvaz, with a subtropical hot desert climate. Main plots consisted of four irrigation regimes including; control (irrigation treatments: 80%, 80%, 80%, and 80% of field capacity), mild (irrigation treatments: 60%, 80%, 80%, and 40% of field capacity), moderate (irrigation treatments: 60%, 60%, 60%, and6% of field capacity) and severe (irrigation treatments: 40%, 60%, 60%, and 60% of field capacity), and sub-plots consisted of two sunflower cultivars including; Padideh and Goldasht. Irrigation treatments were applied at stem elongation, branching, flowering, and grain-filling stages.

Deficit irrigation caused a significant reduction in stomatal conductance, photosynthetic rate, chlorophyll index, grain, and oil yield, but increased catalase and peroxidase enzyme activities, carbohydrate and malondialdehyde concentrations. Goldasht cv. with the highest stomatal conductance, photosynthetic rate, chlorophyll index, catalase, and peroxidase enzyme activities, carbohydrates concentrations, and with the lowest malondialdehyde concentrations and oil percentage had the highest economic oil and grain yield and it is recommended in a water-limited condition. The highest levels of antioxidant enzyme activity and lowest malondialdehyde content under water deficit conditions may provide better drought tolerance in this cultivar. The oil yield of both cultivars significantly decreased under moderate and severe heat stress by 31, 43, and 63%, respectively, when compared to the control. Goldasht cv. with a higher grain yield showed a higher oil yield.

Different irrigation regimes applied at different growth stages differently influenced the physiological and biochemical characteristics of safflower cultivars. The developmental stage and severity of water deficiency played an important role in cultivar responses to deficit irrigation regimes. Totally, a moderate deficit regime led to a 43% decrease in oil yield, but by saving about 40% of available water, this treatment is recommended as a suitable strategy for water management to reduce water use in this area.

Oilseed rape (Brassica napus L.) is a traditional oil crop in Iran. Conventional oilseed rape production during the past decades has been performed through manual sowing, transplanting, and harvesting. In cold and temperate regions of the Iran in the Karaj region, due to delays in harvesting the previous crop such as corn, canola planting date is delay and it is not possible to planting oilseed rape seeds directly. Problems such as supplying primary soil water for crop establishment of canola fields, possibility of damage from cold and frost stress and late season drought due to delayed planting are the main problems of canola cultivation in Karaj region (Jabbari et al., 2022). Because of this, canola transplanting can solve the problems and be a good choice in these kinds of situations (Zeinalzadeh-Tabrizi et al., 2022). Although there have been many seeding rate studies done for canola, the optimum seeding rate and plant population for canola is not known. Optimum density for canola depends on both biological and economic factors. verall economic optimum plant density for canola was 30 to 40 plants m-2 (French et al., 2016). On the other hand, the transplanting method (bare-root or potted-root transplant), transplanting density and the number of seedlings per hole one seedling or two seedlings are very important to achieve the highest seed yield.

In order to agronomic evaluation of winter canola in seeding and transplanting systems with different plant densities under delayed cultivation conditions in the Karaj region, an experiment was conducted as a randomized complete block design with three replications in two cropping years, 2019-2020 and 2020-2021. Experimental treatments included direct sowing of seeds as a control at a rate of 6 kg/ha; transplanting with densities of 20, 30, and 40 plants per square meter, each density with both bare-root transplant and potted-root transplant; and also with one seedling or two seedlings in the planting hole. During the experiment, traits including Days to flowering time, flowering duration, growth period, plant height, stem diameter, branch number, silique length and diameter, silique per plant, seed number per silique, 1000-seed weight and seed yield were recorded. Combined analysis of variance carried out by SAS statistical analysis software and the least significant difference (LSD) test was used to compare treatment means with a probability threshold of 0.05.

The results of combined analysis showed that seed yield in the treatments of potted-root and bare-root seedling was between 686 and 1142 kg.ha-1 more than seeding cultivation. Yield reduction in seeding cultivation was due to the reduction of yield components, especially the number of silique per plant. Also, among all the investigated treatments, the highest seed yield (4395 kg.ha-1) was observed in the treatment of bare-root seedlings with a density of 40 plants with one seedling in the hole, which this issue was related to the relatively long flowering duration, noticeable superiority for silique per plant and high 1000 seeds weight. An independent comparison of bare-root and potted-root transplant treatments showed that in the total of two experimental years, bare-root treatments caused a significant decrease of 7.3% in days to beginning of flowering and 13.3% increase in the length of the flowering period, 7.2% in plant height, 42.7% in siliques per plant and 17.1% in the seed yield. Early maturity and higher of siliques number and number of seeds in siliques led to the superiority of seed yield in the bare-root treatment compared to the potted-root treatment. Mentioned issue was related to more competition between seedlings in the pot at the the potted-root treatment and the greater use of soil space for root development and less competition between seedlings in bare-root treatment.

Generally, results showed that bare-root transplant treatments were superior to potted-root transplant treatments for yield components and seed yield. Therefore, in the conditions of delayed cultivation of canola, it is recommended to bare-root transplanting with a density of 40 plants per square meter and one seedling in the planting hole, especially in the Karaj region.

Planting date is considered to play a crucial role in decision-making processes of crop production and management, especially in the areas where plants are impacted by deleterious factors such as terminal cold and drought, early drought stress and extreme heat (Behdani & Jami Al-Ahmadi, 2008). In the studies conducted in different regions, delay in planting time in both autumn and spring resulted in decreases in grain, and oil yield, number of seeds per head, number of heads per plant, 1000-seed weight, plant height, number of leaves per plant, and dry weight of shoot (Solhe oskouei et al., 2016 ; Deltalab et al., 2011). Therefore, this experiment was performed to find the best winter sowing date for different cultivars and to investigate changes in grain yield, yield components and oil of safflower cultivars under delayed cultivation.

The experiment was carried out in a split plot arrangement based on randomized complete block design with three replications in two years, 2013 and 2014 at Zahak Agricultural and Natural Resources Research Station, Sistan and Baluchestan province. The main plot consisted of five sowing dates including: 21th Dec., 9th Jan., 29th Jan., 19th Feb. and 10th Mar. and the subplot was assigned to four cultivars; Golldasht, Padideh, Faraman, Gollmehr, which were independently randomized. In this study, yield characteristics and components of grain yield, agronomic and phonological traits in addition to grain oil content were investigated. Statistical analysis was performed using MSTAT-c software.Results &

The combined analysis of variance indicated significant effect of year, and cultivar on the all traits phenological, morphological, grain yield and its components as well as oil content. Goldasht and Faraman cultivars, at all the sowing dates, showed shorter time to physiological maturity. The highest mean of plant height (114 cm) was observed at the first sowing date (21th Dec.), which was 20% and 28% higher than the fourth (19th Feb.) and the fifth (10th Mar.) sowing dates, respectively. Padideh and Golmehr cultivars showed the highest plant height. Grain yield in the first year increased by 6% relative to the second year. The seed yield at the first sowing date (21th Dec.) was 1611 kg.ha -1, which was 16%, 24%, 37% and 44% greater than at the second (9th Jan.), the third (29th Jan.), the fourth (19th Feb) and the fifth (10 Mar.) sowing dates, respectively. A delayed planting from 21th Dec. declined the grain yield at a rate of 10 kg.ha-1 per day. The results for the triple interactive effects of cultivar × planting date × year showed that the highest grain yield was achieved in the first year × first sowing date (21th Dec. × the genotypes of Faraman and Goldasht with a mean yield of 2090 and 1758 kg.ha-1. Oil content was increased as the planting date was shifted from 21th Dec. to 10th Mar. The oil percentage at the first sowing date (21th Dec.) relative to the fifth sowing date (10th Mar,) increased by about 9% and among the cultivars, Padideh and Golmehr had 9% and 6% more oil content than Goldasht and Faraman, respectively. Seed yield showed the highest positive and significant correlation coefficient with number of boll per plant (r = 0.76 **), number of grain per boll (r = 0.75 **), and 1000-seed weight (r = 0. 47 **).

Losing the appropriate planting date for winter cultivation system of safflower, shifting from early January to early February, can lead to a compensatory seed yield production. In fact, at these dates, suitable environmental conditions facilitate increased duration of vegetative growth and the formation of higher yield components such as number of florets per boll, boll per plant and grain per boll as compared to late planting date. Among the studied cultivars, Faraman and Goldasht produced the highest grain yield at the all planting dates, maybe due to the higher number of grain per boll and 1000-seed weight. To achieve maximum grain and oil yield in winter safflower cultivation for the conditions of Sistan region, sowing from early January (first date 21th Dec.) to late January (second date (9th Jan) using early maturity cultivars, such as Faraman and Goldasht cultivars is recommended.

Ecosystem services are defined as services provided by the natural environment. These services produce outputs or effects that directly and indirectly impact human well-being, culture, and the global economic system (Feng et al., 2018; Ma et al., 2020). Quantifying the services of agroecosystems is one of the most important strategies to increase attention to these services and provide appropriate solutions to maintain and sustain these services. The development of intensive agriculture has transformed agricultural landscapes into simple, low-coverage single-product systems similar to semi-natural habitats. This change has led to a sharp decline in biodiversity and a reduction in the provision of ecosystem services to agriculture. It has been confirmed that among ecosystem services, pest, and weed control, and pollination have significant impacts on global agricultural production.

In this study, 8 plots were selected from different plots of autumn crops included barley, and triticale. In this study provisioning, supporting, regulating services in the cultivation of barley and triticale fields of Dasht-e Naz, Sari Agricultural Company (Mazandaran province) were evaluated and quantified, during 2019-2020. In this study, some ecosystem services such as insect and weed biodiversity (using Shannon-Weiner, Simpson, Margalf, Uniformity and Menhinick indices), soil microbial respiration, carbon sequestration, organic matter, abundance of earthworms, grain yield, protein content oxygen production, and soil protection (by the stability of aggregates) were evaluated and quantified. Soil samples were taken from a depth of 0-30 cm before barley and triticale planting in November 2019 and after harvest in June 2020 for assessment of rate of microbial respiration, organic matter and carbon sequestration. Also, oxygen production was estimated based on net primary production. A sampling of plant biodiversity and yield of autumn crops was performed based on the W shaped pattern with 0.5×0.5 m2 quadrate. In this study, insects were collected in ways: yellow sticky trap, insect nets, and ground trap. Sampling was done from late March to mid-April 2020. All data were analyzed with SAS version 9.4 and T-test was used to compare the means between cultivars at the 5% probability level.

The results showed that the highest amount of oxygen production was obtained at about 17.66 and 16.57 tons per hectare from 12 and 16 fodder plots for barley and triticale, respectively. In this research, the highest amount of carbon sequestration (2.67 tons per hectare) and the activity of microbial respiration before planting and after harvesting the crop were 91.40 and 45.95 milligrams of CO2 per kilogram of soil per day, respectively andearthworm abundance (13 per square meter) belonged to plot 18. The evaluation of the biodiversity status in insects and weeds showed that the highest Shannon-Weiner diversity index in weeds was 2.65 and 2.89 from plots 12 and 16 of barley and triticale fodder, respectively. Also, in 12 plots of barley and 16 plots of triticale, because the purpose of farming was to produce fodder, herbicides were not used compared to other plots. In another study, it was observed that the highest Shannon-Weiner diversity index was obtained from triticale farms (1.00) and the lowest (0.14) from winter wheat farms(Sawicka et al., 2020). This could increase the Shannon-Weiner index. Also, the Shannon-Weiner index of insect communities was calculated as 2.37 and 2.49 from 19 and 16 plots, for barley and triticale, respectively.4 beneficial insects named Syrphus ribesii, Chrysoperla carnea, Coccinella septempunctata Linnaeus and Apis ellifera mellificawere recorded in the barley and triticale plots studied.

The results of this study showed that crop management and implementation of intensive agricultural systems were effective in providing many ecosystem services of barley and triticale fields. So, these services were affected by various factors, such as cultivar type, crop rotation, and tillage methods. In general, intensive agriculture is associated with climate change and biodiversity loss and alternatively, the reduction of ecosystem services including regulating and provisioning services is inevitable. Therefore, adopting management of agroecosystems associated with natural ecosystems can help to provide more ecosystem services in agroecosystems and maintain their sustainability level.Acknowledgements:We are thankful to Gorgan University of Agricultural Sciences and Natural Resources (GUASNR), the agricultural company of Dasht-e-Naz Sari and Dr. Hamid Sakinin for all his companions and supports.