Dongxiao Zhao

The shortage of high-quality forage and the need for alternative protein sources are critical challenges for livestock production in northern China, where cold winters and saline–alkaline soils limit crop options. Mulberry (Morusalba L.) is a promising high-protein forage, yet few varieties have been bred for these conditions. Here, we report the breeding of ‘Fengyuan No. 1’, developed through systematic evaluation of 31 mulberry accessions for five forage traits, followed by a 4 × 3 factorial crossing design using four female parents (‘8036’, ‘Dahongpao’, ‘Jinqiang 63’, ‘Hongguo 2’) and three male parents (‘Nongsang 14’, ‘Yu 2’, ‘Yiyuan Huanglu’) selected based on comprehensive evaluation and complementary agronomic traits. Among the nine hybrid families with sufficient seed, family X01 (‘8036’ × ‘Nongsang 14’) ranked first in a three-year (2011–2013) comprehensive evaluation of growth traits using membership function analysis and was subsequently named ‘Fengyuan No. 1’. Multi-location (Shandong, Anhui, Shaanxi) field trials (2018–2021) with ‘Fengchi’ as the control showed that ‘Fengyuan No. 1’ achieved an average annual leaf yield of 12,596.48 kg DM·ha⁻¹ (+14.20%) and total branch–leaf biomass of 25,341.95 kg DM·ha⁻¹ (+13.36%). Leaf crude protein reached 30.87% on a dry matter basis (+25.64% vs. control). Silage prepared from this variety exhibited excellent fermentation quality (pH 4.10) and a relative feed value of 272.46, exceeding alfalfa silage standards. The variety maintained 100% survival at 0.4% NaCl and a 13.74% biomass advantage over the control on saline–alkaline field soils, with winter-desiccated shoot tips reduced by 53%. These results establish ‘Fengyuan No. 1’ as an elite forage mulberry for the Yellow River Basin and similar ecoregions.

The scarcity of resources has constrained the supply of conventional feedstuffs for livestock production. Consequently, mulberry (Morus spp.), known for its high protein content and bioactive compounds, has been developed as a promising alternative feed. However, the optimal water–fertilizer ratio for cultivating feed mulberry and the underlying physiological and agronomic mechanisms remain poorly understood. To address this, a two-year field experiment (2023–2024) was conducted to investigate the effects of water–fertilizer coupling on feed mulberry yield, water use efficiency (WUE), and soil quality. This experiment employed a split-plot design with three irrigation levels (I1 = 45, I2 = 90, and I3 = 135 mm) and four fertilizer rates (F1 = 0, F2 = 150, F3 = 225, and F4 = 300 kg·ha⁻¹). The results demonstrated the following: (1) The variation trends in SWC were consistent with those of soil available N, P, and K contents. Under water–fertilizer coupling, the total water consumption peaked in the I3F3 treatment, with values of 639.9 mm and 703.5 mm in the two years, respectively. (2) The I3F3 treatment produced both the highest yield (37.19 and 41.66 t·ha⁻¹) and the highest leaf N, P, and K contents among all treatments. (3) Water and fertilizer use efficiencies exhibited parabolic trends in response to increasing irrigation and fertilizer inputs. The highest agronomic nitrogen efficiency (AEN) was observed in I2F2. (4) The AMOS 26 model further revealed that soil nutrient content had the strongest direct positive effect on yield (standardized coefficient = 0.68), followed by total water consumption (0.33). And irrigation significantly enhanced soil nutrient availability (standardized coefficient = 0.29). In summary, the I3F3 combination achieved the highest yield and water use efficiency, whereas the I2F2 treatment exhibited the highest AEN. This trade-off suggests that the optimal strategy depends on management objectives (yield maximization vs. resource conservation) in the North China Plain.

The scarcity of resources has constrained the supply of conventional feedstuffs for livestock production. Consequently, mulberry, known for its high protein and bioactive compounds, has been developed as a promising alternative feed. However, the optimal water-fertilizer ratio for cultivating feed mulberry in the North China Plain and the underlying physiological and agronomic mechanisms remain poorly understood. To address this, a two-year field experiment (2023–2024) was conducted to investigate the effects of water-fertilizer coupling on feed mulberry yield, water use efficiency (WUE), and soil quality. This experiment employed a split-plot design with three irrigation levels (I1=45, I2=90, and I3=135 mm) and four fertilizer rates (F1=0, F2=150, F3=225, and F4=300 kg·ha⁻¹). The results demonstrated that: (1) with variation trends in SWC consistent with those of soil available nitrogen (N), phosphorus (P), and potassium (K) contents. Under water-fertilizer coupling, the total water consumption in the I3F3 treatment reached its peak, increasing by 11.8% and 9.0% compared to I1F1, respectively. (2) Feed mulberry yield increased with elevated irrigation and fertilizer application. The highest yield, along with the peak leaf N, P, and K contents, was achieved under the I3F3 treatment (135 mm irrigation and 225 kg·ha⁻¹ fertilizer). (3) Water and fertilizer use efficiencies exhibited parabolic trends in response to increasing irrigation and fertilizer inputs. The I3F3 treatment emerged as the most effective management strategy, achieving high yield while maintaining superior WUE. However, the highest agronomic nitrogen efficiency (AEN) was observed in I2F2. (4) The AMOS 26 model indicates that water-driven improvement of soil conditions and soil nutrient effects are the key determinants affecting yield; and the content of soil nutrients significantly affects the nitrogen, phosphorus, and potassium contents of the feed mulberry leaves. In summary, feed mulberry exhibits significant potential for providing feed biomass, particularly by maintaining sufficient forage supply during dry seasons. This study provides critical insights for developing efficient water-fertilizer management practices to support China’s intensified animal production systems.

This study aimed to establish an integrated variety–technology cultivation pathway for the new forage mulberry variety ‘Fengyuan No. 1’, linking salt tolerance mechanisms with practical application. A systematic investigation was conducted via a pot experiment with a 0–5‰ NaCl gradient and a field trial comparing three cultivation modes: Ridge Planting (RP), Furrow Planting (FP), and Flat-Bed Planting (FBP). Key findings are as follows. (1) The salt tolerance threshold was clearly defined: a 100% survival rate at salinity ≤ 4‰ (with no injury symptoms at ≤3‰), and 5‰ identified as the lethal threshold (33.33% survival). Salt stress triggered a resource reallocation strategy, increasing the leaf-to-stem fresh weight ratio from 1.53 (0‰) to 2.78 (5‰) to prioritize leaf photosynthetic function. Stable leaf circularity (0.83–0.87) indicated morphological stress resistance. (2) Optimized cultivation pathways were identified: FBP was the core pathway for maximizing biomass accumulation (root, stem, and leaf fresh weights were 5.0, 2.3, and 1.5 times those of RP, respectively) and resulted in the lowest leaf Na⁺ accumulation (124 mg/kg), making it suitable for lightly to moderately saline–alkali land (≤4‰). FP served as an effective pathway for salt avoidance and height promotion (plant height: 113.18 cm). RP constituted a specialized pathway for high-quality forage, yielding the highest crude protein content (23.3 g/100 g). (3) Cultivation modes significantly affected functional components; FBP activated alkaloid DNJ synthesis (215.16 mg/kg), whereas RP and FP increased osmolyte GABA accumulation (~586 mg/kg). In conclusion, this study integrates a complete technical pathway from salt tolerance mechanism analysis to diversified cultivation options, providing a systematic variety–technology solution for the industrial development of forage mulberry on coastal saline–alkali land.