Hany E.M. Ismail

Utilizing biostimulants like protein hydrolysates is one of the most creative and promising approaches to improving nutritional efficiency, abiotic stress tolerance, or crop quality traits. In the present study, whey protein was hydrolysed with trypsin for 4 h at an enzyme/substrate ratio (1/300, w/w). The obtained whey protein hydrolysates (WPH) were chemically characterized, and their antioxidant activity was estimated. WPH, which was produced using trypsin for 4 hours and presented the highest antioxidant activity. Therefore, it was selected as a bio stimulant with potassium fertilization for enhancing the productivity and tuber quality of sweet potatoes. A field experiment was carried out during the two successive summer seasons, at a private vegetable farm in Faques City, Sharkia Governorate, Egypt, to study the effect of different potassium rates (50, 75, and 100 kg K₂O/fad) and WPH at 0.10 and 0.20% as a foliar application compared to unsprayed plants (control). The interaction between K₂O at 100 kg /fad and spraying with WPH at 0.15% increased shoot dry weight/ plant, N, P, and K uptake by shoots, yield/plant, marketable yield, and total yield/fad, as well as average tuber root weight. It was concluded that the most efficient bio-stimulating foliar spray treatment for increasing sweet potato productivity was WPH (0.20%).

This investigation was carried out in Vegetable Private Farm at Al-Salhyia, Fakous District, Sharkia Governorate, Egypt. Eight potato genotypes were evaluated for tuber yield and its components as well as tuber dry matter (%) under six varied environments which are the combination between three years 2013/2014, 2014/2015 and 2015/2016 and two sowing seasons i.e., fall and summer. The combined analysis of variance showed highly significant differences between genotypes, environments as well as G×E for all studied traits except for aerial stem No./plant which was insignificant, Phenotypic stability parameters revealed that potato genotypes Horaizon and Spunta were highly adapted to favorable environment. These results reflected the importance of environmental factors on the performance of genotype. According to phenotypic stability, the best cultivars were Horaizon and Caruso in most traits. For genotypic stability parameters, most cultivars considered stable in different studied traits. Horaizon, Hermus, Spunta and Inova were the most desired and stable for additive main effects and multiplicative interaction methods stability value (ASV) and regression coeffient (R2) in most traits. The ideal potato culturar was Carus for tuber number/plant, while Hermus was the ideal for average tuber weight, tuber yield/plant, tuber yield/fad., and tuber dry matter according to genotype + genotype x environment.