نشریه پژوهش های به زراعی
سال پانزدهم شماره 4 (زمستان 1402)

In order to investigate the response of the growth and seed yield of the holy thistle (Cnicus benedictus L.) to the plant density and nitrogen rate, an experiment was conducted in the research farm of the Faculty of Agriculture of Tarbiat Modares University. Experimental treatments were arranged in split plots based on randomized complete block design with three replications. The investigated factors in this experiment included four nitrogen rates (0, 50, 100 and 150 kg. ha-1) as the main factor and four plant densities (100, 150, 200 and 250 thousand plants per hectare) as sub factor. At the time of physiological ripening, fresh and dry weight of stem, leaf, seed yield and yield components and harvest index were determined. The results showed that density × nitrogen interaction effect was significant for all measured quantitative traits except the number of sub-branches per plant and the seed number per plant. Nitrogen fertilizer had a significant effect on the disk number per plant and seed number per disk. In total, the density treatment of 10 plants per square meter caused the highest seed yield and yield components in most nitrogen rates. Based on this, for the seed production of holy thistle in order to develop the cultivated area of this valuable medicinal plant, it is suggested to avoid dense cultivations, which are usually recommended to produce the maximum vegetative body of the plant, because according to the findings of this research, the intensification of inter-species competition in density higher than 10 plants per square meter will cause a significant decrease in seed yield.

Dealing with the challenges of food shortages caused by population growth led to the development of agricultural systems dependent on chemical fertilizers, pesticides and insecticides. On the other hand, alternative production systems have emerged in order to reduce the risks of intensive production systems and increase efficiency by applying ecological methods and using biological and organic fertilizers. The purpose of this meta-analysis was to investigate the effects of using biological and chemical fertilizers on the yield of dry weight and essential oil of peppermint and to compare the effects of fertilizer groups with each other. Using the information of articles published in the past 20 years and based on the ROSES protocol, a total of 34 studies were examined. Therefore, Hedges effect size, diffusion error, Begg and Mazumdar's correlation and Kendall’s tau coefficient were calculated using meta-analysis software. The results showed that biofertilizers had a positive effect on increasing the yield of dry weight and peppermint essential oil. The amount of 8 liters of nitroxin per hectare with an effect size equal to (g=1.412) and (g=1.200) with 95% certainty of using biofertilizers increased the dry matter and essential oil of peppermint. The size of the effect of using chemical fertilizers was also more effective than biological fertilizers on the yield of dry weight and essential oil. The results of Begg and Mazumdar's correlation test showed that the effects of chemical fertilizers and biofertilizers on peppermint were homogeneous. The Classic fail-safe N test also showed that the accuracy and precision of the conducted studies is high. Therefore, it is possible to produce peppermint by relying on biological fertilizers in the development of organic agriculture or by combining biological and chemical fertilizers in emerging approaches such as healthy agriculture.

One of the most important problems in crop production is the difference between the actual yield of farmers and achievable yield, which is called the yield gap. Increasing yield in unit area is the key for suppling cerial needs in world. To achieve this aim, it is very important to identify yield limiting factors. This study was done during 2015-2019 to investigate the wheat yield potential in the Ramshir plain of Khuzestan province, for this propose the long-term climatic data, farm management data, physical and chemical properties of soil and plants data were measured in 100 farms and were registered, after the spatial interpolation of the data, the APSIM model was used to simulate the growth and evaluate the gape yield of wheat, in this conditions the yield potential was determined 7091 kg/ha. The results showed that the farmers have reached less than 40% of the achievable yield, which indicates the large gap in yield of this product. Choosing an inappropriate planting date for wheat cultivation with 31% of total yield gap is the main factor of yield reduction, which is due to the lack of access to suitable machinery and seeds for timely cultivation. Also the results demonstrated that the type of soil, water limitation, nitrogen fertilizer used, seed density in square meter and seed variety had 27, 18, 8 and1percent of total gape yield respectively. From the remaining 15% of share, we can mention improper timing of irrigation and fertilizing, improper use of basic fertilizers, poor mechanization and pests. It seems that wheat cultivation at the first opportunity after the relative decrease in temperature at beginning of the autumn season (November) and before cold weather that causes the plant go to sleep (Plant Dormancy), can improve the growth and yield of this crop.

The aim of present study was to investigate the effects of NPK chemical fertilizer management on parameters related to lodging, yield components, grain yield and NPK nutrient uptake in local rice cultivars. The experiment was conducted in farms located in Mazandaran province, Sari, during 2017 and 2018. The experiment was performed as split plot in a randomized complete block design with four replications. The different doses of fertilizer treatments at five levels including F1: N250P150K150, F2: N200P100K100, F3: N150P75K75, F4: N100P50K50, and F5: Control (N0P0K0) as main plot and local rice cultivars at two levels of Sang Tarom and Tarom Hashemi were considered as sub-plots. The results showed that the highest third and fourth internodes lodging index were observed in N250P150K150 and N200P100K100 treatments. Application of N200P100K100 treatment increased the number of fertile tillers per hill (13.25) and finally produced highest grain yield (4806 kg/ha-1), although there was no significant difference with N250P150K150 and N150P75K75 treatments. When the doses of NPK fertilizers increased, the concentration of NPK in grain and straw and as well as grain protein content also enhanced. There was no statistically significant difference between the two cultivars in terms of grain yield and concentration of N and K in plant, but the concentration of P in grain for Tarom Hashemi cultivar was about 8.9% higher than Sang Tarom. According to the findings of this study, the application of N150P75K75 treatment is a better option to improving the grain yield of rice cultivars along with a decrease in chemical fertilizers and subsequent reduced fertilizers costs and environmental damages.

With the aim of evaluating the vegetative growth and yield of three Iranian safflower cultivars in the hot and dry region of Fars province, during the years 2019 and 2020, a factorial split-plot experiment was conducted in randomized complete block design in three replications. The treatments include four levels of irrigation (control, interruption of irrigation at the stages of stem growth, flowering and grain formation) in the main plots, three levels of silicon foliar application (concentration of 100, 150 and 200 mg.l-1) and three varieties of safflower (Faraman, Goldasht and Golmehr) were in sub-plots. The results indicated that the experimental treatments had a significant effect on the studied characteristics. Stopping irrigation during the flowering stage led to a 23% decrease in diameter heads, 58% in number of grain and 28% in 1000 grain weight. Foliar spraying of silicon with concentrations of 150 and 200 mg.l-1 increased the studied characteristics compared to the concentration of 100 mg.l-1. In general, cutting irrigation in the stem stage led to a decrease in the vegetative characteristics of the cultivars and water stress in the stages of reproductive growth, especially flowering, led to a decrease in yield. Also, silicon foliar application in a concentration between 150 and 200 mg.l-1 is sufficient to increase the yield of cultivars in the region and also to reduce economic and environmental costs. Among the varieties, Faraman and Goldasht were the best varieties.

This research was carried out in order to investigate the effect of onion weight and organic and chemical sources of nitrogen supply and nitrogen amount on the morphological traits and stigma yield of saffron plant in Qazvin. This experiment was carried out as a split-plot experiment in the form of a randomized complete block design in 4 replications. The test factors include: sources of nitrogen supply at four levels (N1: 100% urea fertilizer, N2: 67% urea fertilizer + 33% animal manure, N3: 67% animal manure + 33% animal manure and N4: 100% animal manure) and corm weight was in 3 levels (W1: 6-10 grams, W2: 4-6 grams, W3: 2-4 grams). The results showed that the effect of nitrogen supply sources, corm weight and their mutual effect on the number of corms, the number of flowers and the yield of stigma (final product) were significant (P≤0.01). The results of comparing the averages of the mutual effect of nitrogen supply sources and corm weight showed that the highest stigma yield belonged to corms of 6-10 grams in the fertilizer conditions of 33% urea fertilizer + 67% animal manure with an average of 3.662 kg/ha and the lowest amount was related to corms of 2-4 grams under the condition of using 100% of urea fertilizer with an average of 1.877 kg/ha. In general, the results showed that increasing the use of organic nitrogen sources improved the economic yield of saffron. According to the results of this research, the treatment combination of 33% urea fertilizer + 67% animal manure is recommended for the best yield.