Production of sheep wool keratin hydrolysate and evaluation of its effectiveness in promoting maize cultivation.

The purpose of this work is to produce keratin hydrolysate from sheep wool by alkaline hydrolysis and to assess its effectiveness in improving maize plant growth under greenhouse conditions. A hybrid response surface methodology with Box-Behnken design (RSM-BBD) was used to model and optimize the hydrolysis process. The synergistic effects between three critical independent variables including temperature, hydrolysis time, and concentration of KOH on the hydrolysis rate were statistically investigated and optimized. Under optimized conditions, a hydrolysis rate of 95.08% was achieved. The produced hydrolysate consists of water-soluble peptides, free amino acids and potassium ions, making it suitable to be used as a valuable agricultural input material for crop production. Amino acid analysis revealed high levels of proline and phenylalanine, which are responsible for water conditioning and the preservation of abiotic stress as readily available. The efficacy of the produced hydrolysate was assessed in the cultivation of maize as a crop model under greenhouse conditions. Results revealed that the application of the hydrolysate positively influenced the morphological traits of the maize crop such as plant height and leaf surface area. The magnitude of the response to the hydrolysate application depended on its concentration with the most positive effects observed at a dose 2 for the leaf's chlorophyll content, fresh shoot biomass and dry shoot biomass. The application of the hydrolysate improved fresh and dry shoot biomass by 32.5 and 34.4% compared to the control and contributed to the improvement of nitrogen use efficiency by the studied crop. The hydrolysate proved to be beneficial in improving overall plant growth and can be suitable and effective agricultural input for maize cultivation.

Urea-rich sodium alginate-based hydrogel fertilizer as a water reservoir and slow-release N carrier for tomato cultivation under different water-deficit levels.

In this study, a new eco-friendly urea-rich sodium alginate-based hydrogel with a slow-release nitrogen property was prepared, and its effectiveness was evaluated in the cultivation of tomato plants under different water stress levels. The structure and performance of the hydrogel were investigated by FTIR, XRD, TGA, DTG, and SEM. The swelling and release experiments showed that prepared urea-rich hydrogel exhibited a high-water holding capacity (412 ± 4 g/g) and showed a sustained and slow nitrogen release property. A greenhouse pot experiment was conducted using two hydrogel levels (0.1 and 0.5 wt%) under two water deficit levels (30 and 70 % based on required water irrigation). Germination tests indicated that the developed hydrogel fertilizer has no phytotoxicity and has a positive impact on the germination rate even under water deficit conditions. The application of hydrogel fertilizer at 0.5 wt% significantly (p > 0.05) enhanced plant growth parameters such as leaf number, chlorophyll content, stem diameter, and plant length compared to the control treatment. The magnitude of the responses to the hydrogel fertilizer application depended on the concentration of applied hydrogel fertilizer and stress severity with the most positive effects on the growth and yield of tomato observed at a level of 0.5 %. Tomato yield was significantly enhanced by 19.58 %-12.81 %, 18.58 %-22.02 %, and 39.38 %-43.18 % for the plant amended with hydrogel at 0.1-0.5 wt% and grown under water deficit levels of 0, 30, and 70 %, respectively, compared to the control treatment.