Study the Response of Physiological Traits and Grain Yield to Integrated Use of Chemical Nitrogen Fertilizer with Sugarcane Residue Compost in Heat Stress Conditions

IntroductionIn the pursuit of a resilient and progressive agricultural system, the incorporation of diverse fertilizers is deemed essential. This practice not only enhances product quality but also aids in cost reduction. However, over-reliance on a specific type of input can inadvertently lead to unintended repercussions. The unrestricted utilization of chemical fertilizers, for instance, can precipitate adverse outcomes such as imbalanced pH levels, the accumulation of heavy elements, soil structure deterioration, and environmental contamination. Conversely, organic fertilizers, while environmentally friendly, often release nutrients at a slower rate, potentially disrupting optimal plant growth. To attain a balanced and sustainable agricultural approach, the combined application of organic and chemical fertilizers is advocated. Moreover, harnessing the biological potential inherent in soil ecosystems, including beneficial microbial communities encompassing bacteria and fungi, emerges as a promising avenue in cultivating sustainable agriculture. Acknowledging the adverse impact of late-season heat stress on wheat production in Khuzestan and recognizing the significance of reducing chemical fertilizer usage while augmenting organic and biological fertilizers to foster ecological health, this experiment undertakes the exploration of the effects of a synergistic approach. Specifically, it delves into the combined utilization of nitrogen and compost fertilizers, complemented by the incorporation of plant growth-promoting rhizobacteria. This endeavor aims to shed light on how this combined strategy operates within the context of terminal heat stress, assessing its influence on the physiological attributes and yield of the wheat cultivar Chamran 2.Materials and MethodsThis experiment was carried out as split-split plots based on a randomized complete block design with three replications in the crop year of 2021-2022 in the research farm of Agricultural Sciences and Natural Resources University of Khuzestan. The experimental factors include three planting dates: December 1st, December 20th, and December 10th in the main plots; Six levels of combined use of nitrogen fertilizer with compost fertilizer include control (without nitrogen and organic), 100% nitrogen, 75% nitrogen+ 25% compost, 50% nitrogen+ 50% compost, 25% nitrogen+ 75% compost and 100% compost in sub-plots and two levels of application and non-application of plant growth promoting rhizobacteria in sub-plots. Each sub-plot was 3 meters long and 2 meters wide (with an area of 6 square meters) and included 10 crop lines at a distance of 20 cm from each other. The distance between the main and secondary plots was considered to be half a meter and the distance between the blocks was two meters. After physiological maturity, the plants were harvested and the physiological traits and grain yield were measured.Results and DiscussionVariance analysis showed that the interaction effect of planting date, combined use of nitrogen with compost, and plant growth promoting rhizobacteria, on the traits of relative leaf water content, planting to flowering, and grain yield were significant at the 1% probability level. Also, the interaction effect of planting date and the combined use of nitrogen with compost on all traits except the length of the grain filling period and the length of sowing to physiological maturity was significant at the probability level of 1%. The mean comparison showed that the highest relative leaf water content, cell membrane thermostability, and canopy temperature depression were obtained from the treatment of 100% compost, and the highest traits of the length of sowing to flowering and length of sowing to physiological maturity were obtained in the use of 100% nitrogen. Also, the longest grain filling period, grain filling rate, and grain yield were obtained in the combined use of 50% nitrogen+ 50% compost and plant growth-promoting rhizobacteria, and the lowest value was obtained in the control of not using nitrogen and compost. In general, the delay in planting and the occurrence of terminal heat stress caused a decrease in grain yield, but on different planting dates, the combined use of 50% nitrogen+ 50% compost compared to the treatment of 100% nitrogen increased wheat grain yield.ConclusionAccording to the obtained results, in areas with terminal heat stress, the combined use of 50% nitrogen+ 50% compost and plant growth-promoting rhizobacteria can be considered to increase the growth and yield of wheat

Effect of end of Season Drought Stress on Morphology, Yield Components and Grain Yield of Rapeseed (Brassica napus L.) Cultivars

IntroductionWater is now the main limiting factor for crop production in arid and semi-arid regions. Water-cut or irrigation interruption has been suggested as one of the main strategies agro-technique to get the most benefit from limited water resource available. In this regard, plant growth stage, time of stress induction and the genotype are the main key factors to determine the degree of success. Canola is one of the most important oil crop. It can survive some degree of water stress while there is a need for research to find the most appropriate genotypes for plantations in water-limited areas.Materials and MethodsIn order to determine the effect of water stress at the various growing stages of canola genotypes a split-plot experiment was conducted based on the randomized complete block design with three replications at the research farm of the department of plant production and genetics, Agricultural Sciences and Natural Resources University of Khuzestan, Iran during 2020-2021. Main plots included three irrigation treatments: control (without interruption of irrigation), interruption of irrigation in the beginning of the flowering stage (phenology code 60) to the formation of 50% pods (phenology code 75), and interruption of irrigation in the stage of formation of pods until harvest (Phenology code 99) in the main plots and the cultivars (Long pod, Aram, RGS 003, Jankom, Solar, Hayola 4815, Mahtab, Julius, Agamax and Sala) were arranged in sub-plots with respect to irrigation treatments. At the end of the growing season, plant height, number of branches, silique length, number of pods per plant, number of seeds per pod, 1000 grain weight, and grain oil percentage were measured. Also, after removing the marginal effect, economic performance, biological performance and harvest index were measured.Results and DiscussionOur results revealed there was a significant interaction effect between irrigation interruption stress and genotype on all studied traits. The number of sub-branch among cultivars varies as a result of Irrigation interruption stress. The genotypes of the long pod and Hayola 4815 had the highest number of branches compared to other genotypes when irrigation was interrupted at the flowering stage up to 50%, while when applied stress at the stage of flowering up to harvest, genotype, solar exhibited the highest number of sub-branch. The lowest number of sub-branches in all interruption of irrigation and control treatments was obtained by Jankom genotype. The mean comparisons in the conditions without irrigation interruption (control) the highest percentage of seed oil was obtained from Solar (48.3%), Hayola 4815 and 4815 (46.3%), stress application in flowering stage up to 50% sowing of a long pod (45%) and Hayola 4815 (43%) genotypes in the sowing stress to harvest the highest percentage of seed oil from Sala and Long pod genotypes with average (44.3%) the lowest percentage of seed oil in all present treatments belonged to Jankom genotype. In the present study, the highest (2093.8 kg.ha-1) and the lowest (540 kg.ha-1) grain yield and the highest (986.51 kg.ha-1) and the lowest (191.21 kg.ha-1) grain oil yield in both conditions without irrigation interruption (control) and terminal drought stress were obtained from Hayola 4815 and Jankom genotypes, respectively.ConclusionThe highest and the lowest grain yield, seed oil and biological yield were obtained from Hayola 4815 and Jankom, respectively. According to the results, Hayola 4815, long pod and Solar are highly recommended to cultivate in the regions where there is terminal water stress at the end of the growing season

Hydrotime Analysis of Yellow Sweetclover (Melilotus officinalis (L.) Lam.), Wild Mustard (Sinapis arvensis L.) and Barley (Hordeum vulgare L.) Seed Germination

Introduction: Seed germination is one of the key stages in the life cycle of plants that can ultimately affect their fitness in the environment. The temporal pattern of seed germination is extremely depended on the soil water potential (Ψ) of the germination medium, as this determines the equilibrium water content of the seed. As for temperature, there is a minimum Ψ that must be exceeded in order for seeds complete germination, and seeds in a population vary in the value of this minimum or base Ψ. The germination of a seed population in response to the reduced water potential is modeled using the hydrotime model. According to this model, the time to germination for a given seed fraction (g) is inversely related to the difference between the current seed Ψ and the base water potential (Ψb) for that fraction (Ψb(g)). The hydrotime model functions are well in matching both the timing and the percentage of germination of seed populations in relation to their Ψ environment. In addition, the model outputs which are significant physiologically and ecologically and the parameters of the model can be used to characterize the properties of seed populations. Normal distribution of Ψb among seeds within a population is one of the assumptions of the hydrotime model. However, this assumption may not be met in many species and thus can result in poor predictions. We tried to investigate empirically the validity of this assumption, to compare the fit of alternative distributions and make recommendations to improve germination modeling procedures. Materials and Methods: Seed germination of Melilotus officinalis, Sinapis arvensis and Hordeum vulgare were tested across a range of water potentials (0, -0.2, -0.4, -0.6 and -0.8 MPa for M. officinalis and S. arvensis and 0, -0.3, -0.6, -0.9, -1.2 and -1.5 MPa for H. vulgare) and germination responses were described by the hydrotime models based on twelve statistical functions including Normal, Beta, Gamma, Loglogistic, Weibull, Gumbel, Birnbaum-Saunders, Inverse-normal, Log-normal, logistics, Rayleigh and Inverse-gamma. Four replicates of 50 seeds were spread evenly within 9-cm-diameter Petri dishes, each containing a Whatman No 1 filter paper. Each filter paper was moistened with 6 mL of polyethylene glycol (PEG) solutions or distilled water (0 MPa). Osmotic solutions were prepared by dissolving PEG 6000 in distilled water according to the Michel (1983) equation. Germinated seeds (radicle protrusion of>2 mm) were counted daily two or three times for 20 days. All distributions, having been formulated into the hydrotime model, were fitted to data using the PROC NLMIXED procedure of SAS, with the default optimization technique of dual quasi-Newton algorithm. Results and Discussion: The results showed that the estimated parameters of the hydrotime model developed on the basis of Beta distribution had more certainty than the other distributions (AICc=-556.60 for M. officinalis, AICc=-847.70 for S. arvensis and AICc=-1034.20 for H. vulgare). Based on the Beta hydrotime model, values of the hydrotime constant (θH) and water potential threshold for beginning of M. officinalis seed germination (δ) were estimated to be 14.01 MPa h and -0.85 MPa, respectively. For S. arvensis, θH and δ estimated to be 22.23 MPa h and -0.98 MPa, respectively. Estimated θH and δ for H. vulgare was 48.69 MPa h and -2.47 MPa, respectively. Results of this research are in contrast to assumption of a normal distribution of base water potential of a seed population. Hence, before using a hydrothermal time model to make predictions, the distribution of base water potential within a seed sample should be examined and an appropriate equation should be selected.. The results indicated that among all three species, the Beta distribution resulting in more accurate predictions than the other distributions. The hydrotime model based on Beta distribution predicts an actual value for the phase of delay germination. In fact, less skewed in predicted germination using beta model can be related to more accurately of this function to predict the onset of germination. Shape parameter gives high flexibility to this model and allows more accurate prediction of delayed germination phase. In addition, the hydrotime model based on Beta distribution was able to prediction germination of species for which the base water potential distribution is symmetrical or unsymmetrical. Conclusion: In this paper, a model based on the beta distribution is proposed which is not only more biologically relevant, but also provides better predictions of germination compared to the conventional model

Effect of Coated Urea Fertilizer on Yield and Yield Components of Sweet Corn (KSC 403) under Deficit Irrigation

This study was carried out to assess the effect of coated urea fertilizer on yield and yield components of sweet corn (KSC 403) under different irrigation regimes, in Ramin Agriculture and Natural Sciences University, Iran by using strip split plot in a randomized complete block design with four replications. Three levels of deficit irrigation (100%, 80 and 60% of calculated water requirement of sweet corn) were assigned as vertical factor and six sources of urea fertilizer (without urea, un-coated urea, sulfur-coated urea fertilizer, starch-coated urea, agar-coated urea and chitin-coated urea) were assigned to horizontal factor. Effects of deficit water and source of fertilizer were statistically significant on plant height, 1000 kernel weight, ear diameter, and number of rows per ear, ear yield, biological yield and harvest index. Maximum of plant height (153.23 cm), 1000 kernel weight (104.51 g), grain yield (9853.3 kg/ha) and biological yield (12471.6 kg/ha) were obtained in chitin coated urea fertilizer. Maximum of ear diameter (4.67 cm) and number of row per ear (13.22) were achieved in agar coated urea fertilizer and that of harvest index (45.79%) was indicated by starch-coated urea. Maximum of length of ear, number of kernels per row and grain yield were 23.65cm, 25.83 and 7142 kg/ha, respectively, and were obtained with the using of chitin-coated urea fertilizer and 100% water requirement. Minimum values of these traits were 13.54 cm, 5.56 and 871 kg/ha, respectively, and were obtained by using of control (no urea application) and 60% water requirement. Results showed that biopolymer coated urea is potent to improve some morphological characteristics and increase grain yield of sweet corn

Effect of Silicon application on Morpho-physiological Characteristics, Grain Yield and Nutrient Content of Bread Wheat under Water Stress Conditions

In order to investigate the effect of silicon application on some physiological characteristics, yield and yield components, and grain mineral contents of bread wheat (Triticum aestivum) under water stress condition, an experiment was conducted in Ramin Agriculture and Natural Resources University, Khuzestan, in 2012. The experiment was arranged in split-plots design in RCBD (Completely Randomized Blocks Design) with three replications. Treatments consisted of drought stress (irrigation after 25, 50 and 75% depletion of Available Water Content) in main plots and silicon (0, 10, 20 and 30 Kg Si ha-1) arranged in sub-plots. Results showed that the effect of drought stress was significant on most traits and led to the increase of electrolyte leakage (EL), cuticular wax, leaf and grain silicon content and grain nitrogen content. But drought led to negative impacts on grain yield and its components, and leaf potassium content, i.e. moderate and severe stresses reduced yield by 17% and 38% compared to control, respectively. Effect of silicon application was significant on all traits except for spike per square meter. Silicon had the greatest impact on EL and led to 35% decrease in this trait. Also, silicon led to increase in leaf and grain silicon contents and grain K content and grain yield and yield components, when applied at 30 kg ha-1. Generally, application of 30 kg ha-1 of silicon led to 6 and 14% increases of grain yield at the presence of moderate and severe drought stresses, respectively. Thus, given the abundance of silicon it can be used as an ameliorating element for planting bread wheat in drought-prone conditions

Effect of Sugarcane Filter Muds, Chemical and Biological Fertilizers on Absorption of Some Macro- and Micro-Elementsand Heavy Metals by Canola (Brassica napus L.)

In order to evaluate the effect of sugarcane (Sacharum officinarum L.) filter muds and chemical and biological fertilizers application on macro- and micronutrient elements and some heavy metals (Pb and Cd) absorption by canola (Brassica napus L.) grains, a factorial experiment was conducted in 2012 in the Experimental Farm of Ramin (Mollasani) Agriculture and Natural Resources University of Khouzestan, Iran. A complete blocks design was used for the experiment with three replications. Different integrated treatments of filter muds and chemical fertilizers (A1: 100% filter muds, A2: 75% filter muds + 25% chemical fertilizers, A3: 50% filter muds + 50% chemical fertilizers, A4: 25% filter muds + 75% chemical fertilizers and A5: 100% chemical fertilizers) along with two levels of biological fertilizers application (with and without biological fertilizers) were investigated. The biological fertilizers investigated in this study were Nitroxin and Barvar2. Application of filter muds led to decreases in nitrogen, phosphorus and Cd of canola seeds. On the other hand, increase of filter muds application led to increase of Zn, Cu, Fe and Pb content in canola seeds. Biological and chemical fertilizers application resulted in increases of nitrogen, phosphorus and cadmium contents in canola seeds. Biofertilizers also increased phosphorus and cadmium contents in canola seeds