Kudzu (Pueraria montana), a vigorous, perennial warm-season invasive legume is widely spread in the southeastern United States and has the potential to be used as feed by ruminants during its growing season from May until first frost (usually in October). The purpose of this study was to determine the nutritive value of kudzu during a drought-prone growing season. Five samples of apical leaves and stems were harvested once a week from random locations within a 43-year-old kudzu infestation grown on a Cecil clay loam (fine, kaolinitic, thermic Typic Kanhapludults) at the Clemson University Experimental Forest (Clemson, S.C.). We report the effects of plant part, sampling date, mean air temperature (MAT), and precipitation on dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), calcium (Ca), magnesium (Mg), phosphorus (P), potassium (K), sulfur (S), zinc (Zn), copper (Cu), manganese (Mn), and iron (Fe) of the kudzu. Dry matter and CP were significantly greater in the apical leaf than in the stem; CP had a significant mean air temperature by plant part interaction. A significant temperature by plant part interaction also existed for Mg. Magnesium was greater in leaf than in the stem at the beginning of the growing season until the end of October, when small differences in Mg concentrations between stem and leaf were observed. Stem and leaf Ca concentrations were not significantly different. Calcium concentrations did vary across the dates (P = 0.002). A significant temperature by plant part interaction existed for Mg concentrations (P = 0.003), Ca to P ratio (P < 0.0001), P concentrations (P = 0.0007), S (P < 0.0001), Zn (P = 0.0053), Mn (P = 0.0014), and Cu (P = 0.006). Overall, kudzu's nutritive value as feed for ruminants during the growing season is highly variable; however, chemical composition was very comparable to other common forages. More frequent and intensive droughts predicted as a result of climate change may limit forage choices; however, kudzu maintains its forage potential for feeding both domestic and wild animals during drought-prone growing season.

Biostimulants, categorized as microbial or non-microbial, including humic substances, seaweed extracts, chitosan, or protein hydrolysates (PHs), have gained significant attention in modern agriculture for their ability to enhance crop productivity, improve nutrient use efficiency, and increase resilience to abiotic and biotic stresses, while reducing dependence on conventional agrochemicals. This review synthesizes the historical development, classification, mechanisms of action, and agronomic benefits of biostimulants, with a particular emphasis on PHs, which are mixtures of amino acids, peptides, and polypeptides derived from plant or animal proteins through enzymatic, chemical, or thermal hydrolysis. The concept of biostimulants has evolved considerably over the past century, transitioning from vague notions of biogenic stimulants to clear definitions guided by international councils and regulatory bodies. Among these, PHs demonstrated the ability to promote plant growth, improve soil microbial activity, and mitigate environmental stresses. Evidence across the literature shows that PHs can deliver measurable agronomic benefits: a meta-analysis of 47 field trials reported an average yield increase of 16.5%, while greenhouse studies documented 21%–35% increases in root and shoot biomass, together with improved chlorophyll content and enhanced uptake of nutrients such as N, Fe, and Zn. These responses are associated with stimulation of root development, nutrient assimilation, osmotic adjustment, antioxidant activity, and beneficial soil microbial processes. The effectiveness of PHs, however, varies with source material, hydrolysis method, crop species, environmental conditions, and application strategy. Plant-derived enzymatic PHs often contain more bioactive peptides, whereas animal-derived PHs may provide higher concentrations of free amino acids and nitrogen. These properties have been reported to reduce reliance on synthetic inputs and contribute to more resilient cropping systems. Despite their promise, inconsistent product composition, incomplete mechanistic understanding, and fragmented regulatory frameworks continue to limit reproducibility and wider adoption. Future research should focus on standardized product characterization, multi-omics approaches, and long-term multi-environment field studies to improve the reliability and practical integration of PHs into sustainable cropping systems.

Soybean [Glycine max (L.) Merr.] productivity is often limited by abiotic stresses such as drought, heat, and suboptimal temperatures during germination and early establishment. Protein hydrolysates (PHs) are biostimulants that can improve crop stress resilience, but whether foliar PH application to parental plants influences untreated F1 progeny seed performance remains poorly understood. This study evaluated whether parental foliar application of three PHs differing in amino acid composition (EZGro 16-0-0, EZGro 18-0-0, and iQForte), an equal-N foliar urea comparator, or a base-fertilizer/no-foliar control altered progeny germination, seedling vigor, and stress responses. Progeny seeds were tested using AOSA rolled-towel germination assays and controlled-environment phytotron assays under drought and temperature stress. Responses were composition-dependent and stress-specific. EZGro 16-0-0 produced PH-specific positive responses for 2023 AOSA germination, vigor index, and root length, and for 2024 root:shoot ratio. EZGro 18-0-0 produced PH-specific responses for germination in both years and for selected dry-matter traits. iQForte produced a PH-specific response for germination under well-watered phytotron conditions. Several additional responses were greater than urea only. These findings indicate that parental foliar PH application can alter selected progeny seedling traits in product-specific and environment-dependent manners, but the underlying biochemical or epigenetic mechanisms require further identification.