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Accurately detecting nitrogen (N) deficiency and determining the need for additional N fertilizer is a key challenge to achieving precise N management in many crops, including rice (Oryza sativa L.). Many remotely sensed vegetation indices (VIs) have shown promise in this regard; however, it is not well-known if VIs measured from different sensors can be used interchangeably. The objective of this study was to quantitatively test and compare the ability of VIs measured from an aerial and proximal sensor to predict the crop yield response to top-dress N fertilizer in rice. Nitrogen fertilizer response trials were established across two years (six site-years) throughout the Sacramento Valley rice-growing region of California. At panicle initiation (PI), unmanned aircraft system (UAS) Normalized Difference Red-Edge Index (NDREUAS) and GreenSeeker (GS) Normalized Difference Vegetation Index (NDVIGS) were measured and expressed as a sufficiency index (SI) (VI of N treatment divided by VI of adjacent N-enriched area). Following reflectance measurements, each plot was split into subplots with and without top-dress N fertilizer. All metrics evaluated in this study indicated that both NDREUAS and NDVIGS performed similarly with respect to predicting the rice yield response to top-dress N at PI. Utilizing SI measurements prior to top-dress N fertilizer application resulted in a 113% and 69% increase (for NDREUAS and NDVIGS, respectively) in the precision of the rice yield response differentiation compared to the effect of applying top-dress N without SI information considered. When the SI measured via NDREUAS and NDVIGS at PI was ≤0.97 and 0.96, top-dress N applications resulted in a significant (p < 0.05) increase in crop yield of 0.19 and 0.21 Mg ha-1, respectively. These results indicate that both aerial NDREUAS and proximal NDVIGS have the potential to accurately predict the rice yield response to PI top-dress N fertilizer in this system and could serve as the basis for developing a decision support tool for farmers that could potentially inform better N management and improve N use efficiency.

Brown spot of citrus caused by Alternaria citri is one of the emerging threats to the successful production of citrus crops. The present study, conducted with a substantial sample size of 50 leaf samples for statistical reliability, aimed to determine the change in mineral content in citrus leaves after brown spot disease attack. Leaf samples from a diverse range of susceptible citrus varieties (Valentia late, Washington navel, and Kinnow) and resistant varieties (Citron, Eruka lemon, and Mayer lemon) were analyzed. Significant variations (p ≤ 0.05) in mineral contents were observed across reaction groups (inoculated and un-inoculated), types (resistant and susceptible), and varieties of citrus in response to infection of Alternaria citri. The analysis of variance showed significant changes in mineral levels of citrus leaves, including nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), zinc (Zn), sodium (Na), iron (Fe), and copper (Cu). The results indicate that the concentration of N and P differed by 6.63% and 1.44%, respectively, in resistant plants, while susceptible plants showed a difference of 6.07% and 1.19%. Moreover, resistant plants showed a higher concentrations of K, Ca, Mg, Zn, Na, Fe, and Cu at 8.40, 2.1, 1.83, 2.21, 1.58, 2.89, and 0.36 ppm respectively, compared to susceptible plants which showed concentrations of 5.99, 1.93, 1.47, 1.09, 1.24, 1.81, and 0.31 ppm respectively. Amounts of mineral contents were reduced in both resistant as well as susceptible plants of citrus after inoculation. Amount of N (8.56), P (1.87) % while K (10.74), Ca (2.71), Mg (2.62), Zn (2.20), Na (2.08), Fe (3.57) and Cu (0.20) ppm were recorded in un-inoculated group of citrus plants that reduced to 3.15 and 0.76% and 3.66, 1.40, 0.63,0.42, 0.74, 1.13 and 0.13 ppm in inoculated group respectively. It was accomplished that susceptible varieties contained lower ionic contents than resistant varieties. The higher concentrations of ionic contents in resistant citrus varieties build up the biochemical and physiological processes of the citrus plant, which help to restrict spread of pathogens. Further research could explore the interplay between mineral nutrition and disease resistance in citrus, potentially leading to the development of new disease-resistant varieties. [ABSTRACT FROM AUTHOR]

Climate change poses emerging threats to wheat growth in coming future. These threats need to be explored to ensure sustainable wheat production. To do this, the SALTMED model was calibrated using data from experiments conducted on different levels of irrigation and nitrogen doses. The performance of the SALTMED model was assessed based on values of the root mean square error (RMSE), normalized root mean square error (NRMSE), coefficient of determination (R2) and coefficient of residual mass (CRM) that ranged from 0.23–1.82, 0.09–0.17, 0.91–0.93 and −0.01–0.02, respectively for calibration and 0.31–1.89, 0.11–0.31, 0.87–0.90 and −0.02–0.01, respectively for validation. Projections for future climate scenarios for wheat growth indicated that by the end of the century, sowing dates advanced by nine days under the RCP4.5 scenario and eleven days under the RCP8.5 scenario, while harvesting dates shifted earlier by twenty-four days under RCP4.5 and twenty-eight days under RCP8.5. Consequently, the overall crop duration was shortened by fifteen days under RCP4.5 and eighteen days under RCP8.5. Further simulations revealed that the wheat yield was reduced by 14.2% under RCP4.5 and 21.0% under RCP8.5; the dry matter was reduced by 14.9% under RCP4.5 and 23.3% under RCP8.5; the irrigation amount was expected to increase by 14.9% under RCP4.5 and 18.0% under RCP8.5; and water productivity was expected to be reduced by 25.3% under RCP4.5 and 33.0% under RCP8.5 until the end of century. The hypothetical scenarios showed that adding an extra 20–40% more nitrogen can enhance wheat yield and dry matter by 10.2–23.0% and 11.5–24.6%, respectively, under RCP4.5, and by 12.0–23.4% and 12.9–29.6%, respectively, under RCP8.5. This study offers valuable insights into the effects of climate change on future wheat production so that effective contingency plans could be made by policymakers and adopted by stakeholders for higher wheat productivity. [ABSTRACT FROM AUTHOR]

Various iterative methods have been introduced by involving Taylor’s series on the auxiliary function gx to solve the nonlinear equation fx=0. In this paper, we introduce the expansion of gx with the inclusion of weights wi such that ∑i=1pwi=1 and knots τi∈0,1 in order to develop a new family of iterative methods. The methods proposed in the present paper are applicable for different choices of auxiliary function gx, and some already known methods can be viewed as the special cases of these methods. We consider the diverse scientific/engineering models to demonstrate the efficiency of the proposed methods.

Foliar application of Atonik (sodium nitrophenolate) at crop critical growth stages is expected to improve crop physiology, morphology, and productivity. The present field study was conducted at the University of Agriculture, Faisalabad in autumn season of 2018 and 2019. Water deficit conditions were imposed by skip irrigation method. Plants were treated with foliar application of Atonik 10 (mg L−1) to evaluate the physiological, morphological, yield, and yield causative attributes of maize grown under deficit irrigation treatments. Randomized complete block design (RCBD) with split plots arrangement was used to layout the experiment having three replications. It was revealed that application of Atonik improved the crop's physiological attributes: relative leaf water contents (RLWC by 10%), chlorophyll contents (14%), and carotenoids content (15%) under water deficit conditions. Similarly, Atonik application augmented the leaf length at maturity, the number of green leaves at harvesting, and the number of grains row−1 of maize by 7%, 20% and 12%, respectively. Moreover, the application of Atonik amended the 100-grains weight, grain yield, and biological yield by 8%, 9% and 20%, respectively. In crux, application of Atonik is an excellent strategy to alleviate the detrimental influence of water deficit on physiological, morphological, and yield causative attributes of maize. [ABSTRACT FROM AUTHOR]

We introduce a new family of iterative methods for solving mathematical models whose governing equations are nonlinear in nature. The new family gives several iterative schemes as special cases. We also give the convergence analysis of our proposed methods. In order to demonstrate the improved performance of newly developed methods, we consider some nonlinear equations along with two complex mathematical models. The graphical analysis for these models is also presented.