The production of citrus, a dominant fruit crop globally, is declining due to biotic constraints such as Huanglongbing (HLB) and abiotic stresses such as low or high soil pH. This study aimed to investigate the influence of soil pH on citrus root morphology, nutrient uptake dynamics, and overall root health. Forty 'Valencia' sweet orange [Citrus sinensis (L.) Osbeck] trees grafted on Swingle citrumelo rootstock [C. paradisis x Poncirus trifoliata (L.) Raf] were divided into four groups by pH treatment (n = 10). Trees planted in rhizotron boxes were irrigated three days a week with four different water pH levels: 5.5, 6.5, 7.5, and 8.5. Soil acidity and alkalinity were routinely monitored with pH probes. The concentration of essential macronutrients and micronutrients from the soil, plant tissue, and leachates was also analyzed monthly to evaluate nutrient uptake efficiency. Parameters such as root length, root surface area, and root diameter were measured to assess the morphological changes in citrus tree roots under different pH treatments. After irrigation, soil pH on treatment with pH = 5.5 decreased drastically since sandy soils acidify more quickly. Soil pH levels for treatments irrigated with solutions at pH 6.5 and 7.5 consistently maintained near-neutral levels, with the former gradually decreasing soil pH over time and then later increasing the soil pH to alkaline levels. The soil P and S concentrations were high at pH = 5.5, contrary to the Mg and Ca concentrations, which were low at the same pH level. Soil pH showed a significant and negative correlation with S, P, and Fe, indicating a decrease in these soil nutrients as soil pH decreased and a nonsignificant positive correlation with Cu. At pH = 5.5, there was significantly higher root growth, which indicates that acidic soils (similar to pH = 5.5) can enhance root growth in citrus trees. Acidic soils stimulate root growth, particularly around a pH of 5.5; citrus roots exhibit remarkable resilience and internal compensation mechanisms in response to pH changes. Optimizing soil pH and nutrient management can mitigate the impacts of HLB and promote the resilience of citrus trees. Trees irrigated at pH of 8.5 showed a trend of fewer living roots and lower cumulative root growth, emphasizing the possibility of root damage due to high soil pH.

Purslane (Portulaca oleracea L.) is an herbaceous species that is traditionally consumed across the world due to its nutraceutical quality, boasting anticancer, anti-inflammatory and antidiabetic properties. These traits render purslane an attractive wild edible species for research and commercial exploitation. The current study examined the effect of different nitrogen (N) concentrations (100-200 mg L-1; as N100, N200) in combination with different levels (decreased 0.66-fold: dec, recommended 1-fold: rec, or increased 1.5-fold: inc) of phosphorus (P; 47-70-105 mg L-1) and potassium (K; 250-350-525 mg L-1) in the nutrient solution (NS) used in hydroponic nutrient film technique (NFT) cultivation. The N200_PKinc NS resulted in improved crop growth compared to N200_PKrec NS, suggesting a positive correlation between optimal N levels (i.e., 200 mg L-1) and increased P and K levels (105 and 525 mg L-1, respectively). Plants grown in N200_PKinc revealed decreased antioxidant activity (e.g., DPPH, FRAP, and ABTS), phenols and flavonoids, while simultaneously increased total soluble solids levels. The recommended levels of P and K mirrored low levels in lipid peroxidation, mainly due to the increase in catalase enzymatic activity. Higher nutrient use efficiency was observed when both N100_PKinc and N200_PKinc were applied, resulting in higher yield and enhanced plant growth, while N100_PKinc produced plants with increased antioxidant activity. These findings suggest that both (N200_PKinc and N100_PKinc) NS have potential benefits for the hydroponic cultivation of purslane, with the latter NS offering additional advantages in terms of higher produce quality.

Fibrous plants with higher biomass, particularly industrial hemp, have ability to withstand and accumulate significant quantities of heavy metals from contaminated environments. The present study aimed to evaluate the dynamics of different levels (ratios) of macronutrients nitrogen, phosphorus and potassium (NPK) viz., NPK1--NPK (1:1:1); NPK2--NPK (2:1:1); NPK3--NPK (3:1:2); NPK4--NPK (4:1:2) on hemp growth and Cu contents under various levels of Cu stress (100, 400 and 800 mg kg- 1 on dry soil basis using CuSO4 & sdot;5H2O). Results revealed that by increasing the Cu stress, growth and biomass decreased linearly and lipid per oxidation and enzymatic antioxidants increased. Balanced application of NPK improved the biomass and decreased the membrane damage by the modulation of malonaldehyde contents. Maximum concentration of Cu in roots (377.47 +/- 4.90 mg kg-1), shoots (137.45 +/- 5.60 mg kg-1) and (150.07 +/- 3.57 mg kg-1) was recorded at Cu3NPK2 treatment as compared to control. Maximum translocation factor (TF) and bioaccumulation coefficients (BAC) in the shoots and leaves of hemp plant were noticed where Cu stress was applied at the rate of 100 mg kg- 1. However, BAC and TF were below 1. The NPK2 treatment enhanced biomass and increase Cu content both in leaves and stems, rather than the roots. Our study suggests that balanced application of NPK is a practicable approach to alleviate Cu stress and improve biomass production of industrial hemp plant. These findings indicate that optimum nutrient supply, under Cu stress, can maximize the growth potential and overall health of industrial hemp, making it a viable option for phytoremediation and sustainable agriculture on contaminated soils.