Irrigation Level Effects on Herbage Yield and Nutritive Quality of Forage Soybean (Glycine max (L.) Merr.): A Multivariate and Predictive Modelling Approach for Water-Limited Environments
Journal of Agronomy and Crop Science, cilt.212, sa.5, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 212 Sayı: 5
- Basım Tarihi: 2026
- Doi Numarası: 10.1111/jac.70244
- Dergi Adı: Journal of Agronomy and Crop Science
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, BIOSIS, CAB Abstracts, Environment Index, Geobase, INSPEC, Academic Search Ultimate (EBSCO), Biomedical Reference Collection: Corporate Edition (EBSCO), Engineering Source (EBSCO)
- Anahtar Kelimeler: climate change, forage legume, gas-methane production, PLS regression, water-use efficiency, yield response factor
- Çanakkale Onsekiz Mart Üniversitesi Adresli: Evet
Özet
This study was conducted to determine the effects of five irrigation levels, corresponding to 25%, 50%, 75%, 100% and 125% of the weekly irrigation amount required to replenish the effective root zone to field capacity (IT25–IT125), on the herbage yield and quality of forage soybean (Glycine max (L.) Merr.) over two growing seasons (2024 and 2025) in Kayseri, Türkiye, using a randomized complete block design with three replications. The site has a semi-arid climate, and both growing seasons were warmer and drier than the long-term average. Irrigation was applied through a drip system; crop water consumption, water-use efficiencies and the yield response factor (ky) were calculated, and biochemical composition, macro- and micro-mineral contents, in vitro gas and methane production, metabolizable energy and organic matter digestibility were determined. Green herbage, dry herbage and crude protein yields increased markedly from IT25 to IT100 (9.01 to 34.07 t ha−1, 3.27 to 9.14 t ha−1 and 0.79 to 1.85 t ha−1, respectively) and declined at IT125. Water productivity depended on the basis used: green-herbage crop water productivity was highest at IT100, whereas dry-herbage crop water productivity and irrigation-water productivity were greatest under severe deficit (IT25). Cell-wall fractions increased up to IT100 while crude protein concentration declined, and several mineral and in vitro fermentation traits reached their highest or near-highest values around IT100. Leakage-controlled partial least squares (PLS) models fitted without year or irrigation level as predictors showed higher repeated nested cross-validated performance for the three yield traits (R2 = 0.784–0.834) than for metabolizable energy (ME; R2 = 0.696) and organic matter digestibility (OMD; R2 = 0.718), with empirical Y-randomization p = 0.001 for all targets. PCA and CDA further showed a strong irrigation-related multivariate gradient together with a distinct contribution of between-year variation. Overall, IT100 was the best-performing treatment under the conditions evaluated, providing a practical experimental reference for balancing forage yield, water-use efficiency and herbage quality in comparable semi-arid environments.