Ultramafic soils, particularly those affected by mining, often contain toxic nickel (Ni) levels that hinder plant growth and ecosystem recovery. This study assessed engineered biochar–nanocomposite amendments to improve vetiver (Chrysopogon zizanioides) growth, biomass, and Ni phytoextraction in Ni-rich ultramafic soils from Santa Cruz, Zambales, the Philippines. Seven samples were tested: T₁—control (no application); T₂—biochar; T₃—nanocomposite; T₄—biochar + nano-silica; T₅—biochar + nano-calcium; T₆—biochar + nano-chitosan; and T₇—biochar + nanocomposite. Biochar combined with nano-silica (T4) significantly enhanced vetiver growth, producing the highest root, shoot, and total biomass (469.97 g plant⁻¹), indicating improved plant tolerance under Ni stress. The highest shoot Ni concentration (24.52 mg kg⁻¹) and translocation factor (0.56) were observed in the biochar + nano-chitosan treatment (T6), suggesting increased Ni bioavailability and uptake. However, translocation factor values remained below unity across all treatments, indicating limited Ni transfer from roots to shoots and a dominant phytostabilization behavior. Overall, nano-silica-engineered + biochar primarily enhanced biomass production, while nano-chitosan influenced Ni uptake dynamics, highlighting the potential of engineered biochar–nanomaterial amendments for sustainable rehabilitation of Ni-contaminated ultramafic soils.

Morphological characterization of plants is fundamental for plant identification and breeding programs. Abaca (Musa textilis Née) is endemic to the Philippines and belongs to the Musaceae family. Five locally described cultivars-Bisaya, Tabukanon, Agbayanon, Negro and Totoo-are widely used by farmers in Aklan. Detailed morphological data on these cultivars are limited and lack extensive studies, necessitating further research for crop development. This study describes and compares the morphological characteristics of five Abaca cultivars' leaves, peduncles, inflorescences and fruits. A mixed research methodology and field survey were conducted to compare the morphological characteristics across the eight leading Abaca-producing municipalities in Aklan. A linear mixed-effects model (LMM) was employed to account for the variability of the data and handle an unbalanced design where some cultivars are not present in specific locations. The fixed effect of variety was tested using ANOVA derived from the LMM to assess significant differences, followed by Tukey’s HSD method at a 5% level. Results showed that Totoo and Agbayanon had larger leaf morphology while all cultivars exceeded Tabukanon, which had the shortest leaf. Inflorescence morphology varied across abaca cultivars, indicating genetic diversity, which is useful for cultivar differentiation. In peduncle morphology, differences were very significant among all cultivars, Agbayanon shows a greater number of nodes with fruits, Totoo shows a greater number of fruits per node and Negro shows longer fruits, that could be cultivated for seed?production. Such information provides relevant policies that could benefit breeders, researchers, farmers and other users to identify and maximize the crop's potential.

This study investigates the impact of selected soil parameters and integrated fertilizer formulations on the productivity of three legume crops—mung bean, soybean, and cowpea—in order to identify the optimal strategies to maximize yields through reduced nitrogen and bio-augmentation. A five-year experiment composed of 2-year pot trials (2019–2020) and 3-year field trials (2022–2024) was conducted to assess the changes in soil parameters (N, P, K, OM, pH) and yield response of crops with varying amounts (1, 2, 4 kg) of Bradyrhizobium-based biofertilizer combined with a 25–50% reduction in mineral N fertilizer. The biofertilizer was composed of locally isolated strains, which were genetically identified in our previous reports as B. elkanii NE1-6, NE2-1, B. diazoefficiens NE1-65, Bradyrhizobium sp. NE1-19, NE1-34, and NE2-3. The results indicated that the amount of K strongly influenced yield increase for soybean (r = 0.85, p < 0.05) and mung bean (r = 0.67, p < 0.05), while the amount of N had the greatest influence on cowpea (r = 0.60, p < 0.05). Soybean yield was maximized with a 50% reduction in N fertilizer (20 kg N) combined with 2–4 kg biofertilizer, while cowpea and mung bean achieved increased yields at 25% reduced N fertilizer combined with 2–4 kg biofertilizer. This study confirms the viability of integrating Bradyrhizobium-based biofertilizer with a 25–50% reduction in mineral N fertilizer without yield loss by harnessing the efficient N-fixation ability of the strains in the consortium.

This study investigates the impact of selected soil parameters and integrated fertilizer formulations on the productivity of three legume crops – mungbean, soybean, and cowpea – in order to identify the optimal strategies to maximize yields through reduced Nitrogen and bio-augmentation. A five-year experiment composed of 2-year pot trials (2019 – 2020) and 3-year field trials (2022 – 2024) were conducted to assess the changes in some soil parameters (N, P, K, OM, pH) and yield response of the crops with varying amounts (1, 2, 4kg) of Bradyrhizobium-based biofertilizer combined with 25-50% reduction in mineral N fertilizer. The biofertilizer is composed of locally-isolated strains which were genetically identified in our previous reports as B. elkanii NE1-6, NE2-1, B. diazoefficiens NE1-65, Bradyrhizobium sp. NE1-19, NE1-34, and NE2-3. Results indicated that among the soil parameters, the amount of K strongly influenced yield increase for soybean (r = 0.85, p>0.05) and mungbean (r = 0.67, p>0.05) while the amount of N has the highest influence on cowpea (r = 0.60, p=0.05). Soybean yield was maximized with 50% reduction in N fertilizer (20kgN) combined with 2-4kg biofertilizer while cowpea and mungbean achieved increased yields at 25% reduced N fertilizer combined with 2-4kg biofertilizer. This study confirms the viability of integrating Bradyrhizobium-based biofertilizer with 25-50% reduction in mineral N fertilizer without yield loss by harnessing the efficient N-fixation ability of the strains in the consortium.

The fixed insoluble Phosphorus in the soil limits its utilization by crops and thus, the role of phosphate solubilizing bacteria (PSB) is beneficial to increase the P availability in the soil for crops. In order to obtain native isolates that may be used for onion production, three (3) major onion-producing provinces in the Philippines were selected to collect soil samples. A laboratory experiment was carried out to isolate probable PSB employing Pikovskaya (PK) medium with tricalcium phosphate. From a total of 157 isolates that showed a halo zone on PK plates, three (3) representative isolates (one from each location) were selected based on their population dominance and halo zone size for genetic identification using 16S rRNA sequencing. The isolated PSB strains from the three sites showed highly similar nucleotide sequences with Acinetobacter baumannii. In terms of ability to solubilize Phosphorus, the Mindoro Occidental isolate (MOc PSB-RGL-2023) showed the highest solubilizing index of 3.42 mm, followed by Ilocos Sur (IS PSB-RGL-2023) with 3.2 mm, and Nueva Ecija (NE PSB-RGL-2023) with 2.7 mm. These findings suggest the potential of Acinetobacter baumanii as bioinoculant for improving P availability. This study provides a valuable insight as the pioneer report that isolated and characterized possible A. baumannii strains from the three provinces in the Philippines as a prospective PSB bioinoculant.