نشریه پژوهش های به زراعی
سال شانزدهم شماره 2 (تابستان 1403)

In order to study the effect of amount and time of nitrogen fertilizer application on yield and yield components of forage corn after wheat harvesting, an experiment was conducted as split plots Based on randomized complete block design with 4 replications at Qarakhail Ghaemshahr Agricultural Station Associated with Mazandaran Agricultural Research Center in the 2016-2017 crop year. Experimental factors included nitrogen fertilizer application time as main factor in three levels (5-leaf, 9-leaf and 9+5-leaf situation) and nitrogen fertilizer rates as the secondary factor in four treatment levels (0, 125, 250 and 375). The results showed that nitrogen application time did not affect any studied traits, but nitrogen rates had a significant effect on most of the studied traits. The lowest plant height (193.3 cm) and corn length (94.25 cm) were obtained in no nitrogen application, and other nitrogen application treatments were located in a same statistical group. Also, the highest number of grain rows per ear (14.33 and 14.58 rows, respectively) were obtained with 125 and 375 kg nitrogen per hectare, and the highest number of grains per ear row (34.83 and 35.25 grains, respectively) were obtained in 250 and 375 kg/ha nitrogen. Other results showed that the lowest amount of fresh and dry weight of forage corn were obtained in no nitrogen application, so that other levels of nitrogen content were located in same statistical group. Interaction effect experimented factors showed that the highest amount of grain number rows per ear (15.50 rows) was obtained with 375 kg /ha nitrogen applied at the 9-leaf stage.

In order to investigate the efficiency of the CSM CERES-Sweet corn v4.5 model on golden-seeded sweet corn (SC403), a study was conducted at the Gorgan Agricultural Research Center station during 2017 and 2008. The experiment was conducted in a randomized complete block design with three replications. The treatments included sprinkler irrigation and furrow irrigation (Is and IF), with each irrigation treatment including two levels of nitrogen fertilizer at 200 and 300 kg/ha (N200 and N300), which was applied as topdressing in two stages. As a first step, soil samples were taken from the selected field soil in depth 100 cm and physical and chemical analyses were performed on them to be used in the interpretation of the results. The different stages of sweet corn growth were accurately recorded and soil moisture was measured gravimetrically during the growth period at two depths of 0-30 and 30-60 cm. During 2 years of experiment using the CSM-CERES-Sweet corn v4.5 plant systems model from the DSSATv4.5 collections, field data were used as model inputs. The accuracy and efficiency of the model were evaluated using the RMSE statistical index. The evaluation of the CSM-CERES-Sweet corn v4.5 model shows that the model is well able to simulate the phrenological stages of sweet corn (RMSE less than 1%) and also the changes in soil moisture during the growth period. The simulation results in all treatments at a depth of 0-30 cm of soil with an average RMSE of 4.05% were more satisfactory than at a depth of 30-60 cm with an average RMSE of 5.31%. The results of this research showed that the model is able to predict the phenological stages of growth well. The simulation results for soil moisture showed an error percentage higher than 18%.

In order to investigate the effect of nitrogen foliar application at different growth stages on grain yield and yield components of two Wheat cultivars, a factorial experiment was conducted based on completely randomized block design with eight treatments in four replications at Qarakhil Agricultural Research Station. The factors tested included two wheat cultivars, N80 - 19 and the promising line Darya, and the foliar application treatments included foliar application at tillering stage, foliar application at the stem-growing stage, foliar application at early pollination, and foliar application at the grain filling stage. The results showed that plant height and panicle length were affected by the cultivar and foliar application stages. The grain yield and harvest index of Darya cultivar were 4908.25 kg/ha and 32.34% lower than those of N-80-19 cultivar, respectively. Foliar application at the grain filling stage resulted in maximum grain yield and harvest index. Grain protein yield in the N-80-19 cultivar was higher than that of the Omid Bakhsh Darya line, and foliar application at the grain filling stage resulted in the highest grain protein and grain yield.

In order to investigate the effect of drought stress on water use efficiency and some properties of Aloe Vera plants, an experiment was conducted in 2011. A pot experiment was carried out under controlled conditions in a greenhouse as randomized complete block design with four treatments and three replications. Different levels of drought include 100 percent of field capacity (FC) (control treatment, without stress), 75 percent FC, 50 percent FC and 25 percent FC, respectively. Statistical analysis showed that drought had a significant effect on growth parameters. With increasing stress, height, number, width and dry, thickness and size of leaves, fresh and dry weight and root volume was decreased. Water use efficiency was increased with increasing stress. Treatment, 25 percent and 100 percent of FC has the highest and lowest water use efficiency, respectively. The highest amount of chlorophyll a and b and total chlorophyll was obtained in the treatment of 100 percent FC. The amount of proline, soluble sugar and insoluble was maximum in 25 percent FC. In treatments 100 percent FC the highest amount of gel was obtained.

In order to evaluate and determine the value of cultivation and use (VCU) of the six new foreign upland cotton cultivars: 1- Stella, 2- Tesla, 3- AGN126, 4- AGN112, 5- AGN117 and 6- Lodus in comparisons of three common cultivated commercial control cultivars Latif, Golestan and Shayan the research was conducted as a complete randomized blocks design with 4 repetitions during 2020 and 2021 years Golestan (Gonbad Kavoos) province The evaluated traits were: 1-Seed cotton yield, 2-Boll number, 3-Boll weight, 4-Earliness, 5-Gin turn out, 6-length, 7-Fitness, 8-Elongation, 9- Strength, 10- Uniformity, 11- Brightness and 12- Yellowness of fibers and 13- Cultivars tolerance to Verticillium wilt disease. The results revealed each of new foreign cultivars AGN112 and AGN117 with having three superior traits: 1- gin turn out, 2- strength and 3- elongation of fibers and 1- seed cotton yield, 2- boll weight and 3- fiber elongation respectively were superior than control and other studied foreign cultivars but because of AGN112 new foreign cultivar susceptibility to Verticillium wilt disease and Golestan province soils contamination to the disease caused fungus, only AGN117 as a new foreign cultivar cultivation in Golestan province recommendable.

This research was done to investigate the effect of irrigation intervals and organic fertilizer levels on yield and yield components of Hashemi rice in Guilan province. The experiment was done as split plots in the basis of randomized complete block design in three replications in the crop year of 2022 in Guilan province. The main factor included irrigation intervals (3 and 12 days) and the secondary factor included poultry manure at levels (0, 1000, 1500 and 4000 kg/ha). The results of research showed that the effect of irrigation and poultry manure at the level of 1% on paddy, straw and biological yields, plant height, number of productive tillers, length of panicle and weight of a single panicle were significant. Interaction effect of irrigation and poultry manure on the number of productive tillers and the weight of a single panicle was significant at the 1% level, but it was not significant on the height of the plant and the length of the panicle per plant. The highest number of tillers per plant and weight of a single panicle were obtained by the interaction effect of irrigation and poultry manure in irrigation intervals of 3 days and consumption of 1500 kg/ha with an average of 588 and 1.4 g, respectively. The interaction effect of irrigation and organic poultry manure demonstrated that, irrigation Interval 3 days and consumption of 1500 kg/ha organic poultry manure gained the highest yield of paddy, straw and biological yield were respectively with an average of 5957.5, 4613.8 and 10571.3 kg/ha.