Nitrogen (N) is an essential determinant of strawberry growth and productivity. However, plants exhibit varying preferences for sources of nitrogen, which ultimately affects its use efficiency. Thus, it is imperative to determine the preferred N source for the optimization of indoor strawberry production. This study employed the ¹⁵N-tracer technique to investigate the effects of N sources on N uptake, distribution, and use efficiency, as well as the plants’ growth, for ‘Praratchatan 80’ strawberries in a greenhouse. Five treatments were applied: T1 (5.0 mM ¹⁵NO₃⁻), T2 (2.5 mM ¹⁵NO₃⁻ + 2.5 mM NH₄⁺), T3 (5.0 mM ¹⁵NH₄⁺), T4 (2.5 mM ¹⁵NH₄⁺ + 2.5 mM NO₃⁻), and T5 (N-free, control) in a completely randomized design. Significant (p < 0.05) differences were observed in N uptake and distribution and total N concentration among the treatments. Sole NH₄⁺ promoted early N uptake and accelerated flowering, while NO₃⁻ enhanced vegetative growth and later-stage nitrogen use efficiency (NUE). The application of combined NO₃⁻ and NH₄⁺ was most efficacious, balancing the benefits of both N forms. NO₃⁻ treatment enhanced ¹⁵NUE by 46% compared to NH₄⁺, and mixed N sources demonstrated superior and consistent ¹⁵NUE over time. NH₄⁺, alone or with NO₃⁻, expedited flowering by 20 days compared to sole NO₃⁻ and N-free treatments. This study elucidates the importance of the sources of N in optimizing strawberry growth and flowering, providing a foundation for developing tailored N-management strategies. Future research should focus on refining mixed N application ratios and timings, exploring molecular mechanisms of N metabolism, and evaluating long-term impacts on strawberry production sustainability.

Strawberries are valued globally for their nutritional, aesthetic, and economic benefits. Optimizing blue-to-red LED ratios and nitrogen levels is essential for sustainable indoor strawberry cultivation. This factorial study investigated the effects of blue and red LED combination ratios (L1; 1:3, L2; 1:4, and L3; 1:6) and nitrogen levels (N1; 100 and N2; 200 mg/L) on the physiology and performance of strawberries in a plant factory. The results revealed that the interaction of L3 coupled with N2 maximized the vegetative growth of strawberry plants, whereas L2 and N2 produced the greatest biomass, while L2 interacted with N1 to expedite flowering. Photosynthesis and transpiration were enhanced by L3, particularly with 100 mg/L of nitrogen. The highest fruit yield and total soluble solids were obtained at the interaction of L3 and N1. Leaf nutrient analysis showed the highest nitrogen concentration at L1, while potassium increased with higher red LED ratios. The 100 mg/L nitrogen treatment resulted in higher leaf potassium concentrations than the 200 mg/L. These findings emphasize that LED spectra and nitrogen levels interact to optimize the physiology, vegetative and reproductive growth, maximizing fruit yield and quality in indoor strawberry cultivation. The study also concludes that the application of blue and red LED in the ratio of 1:6 with 100 mg/L nitrogen can improve indoor ‘Praratchatan 80’ strawberry performance.

Strawberries are valued globally for their nutritional, aesthetic, and economic benefits. Optimizing blue-to-red LED ratios and nitrogen levels is essential for sustainable indoor strawberry cultivation. This factorial study investigated the effects of blue and red LED combination ratios (L1; 1:3, L2; 1:4, and L3; 1:6) and nitrogen levels (N1; 100 and N2; 200 mg/L) on the physiology and performance of strawberry in plant factory. The results revealed that the interaction of L3 coupled and N2 max-imized the vegetative growth of strawberry plants, whereas L2 and N2 produced the greatest biomass, while L2 interacted with N1 to expedite flowering. Photosynthesis and transpiration were enhanced by L3, particularly with 100 mg/L of nitrogen. Also, the highest fruit yield and total soluble solids were obtained at the interaction of L3 and N1. Leaf nutrient analysis showed the highest nitrogen concentration at L1, while potassium increased with higher red LED ratios. The 100 mg/L nitrogen treatment resulted in higher leaf potassium concentrations than the 200 mg/L. These findings emphasize that LED spectra and nitrogen levels interact to optimize the physiology, vegetative and reproductive growth, maximizing fruit yield and quality in indoor strawberry cul-tivation. The study also concludes that the application of blue and red LED in the ratio of 1:6 with 100 mg/L nitrogen can improve indoor strawberry performance.

The application of cold plasma technology in agriculture includes its use as a nitrate fertilizer, offering an alternative to traditional chemical fertilizers. This study investigated the effects of using plasma-activated water (PAW) as a nitrate source on the growth and flowering of Vanda orchids through two integrated experiments. Plants were treated with different nitrate concentrations (0, 100, 200, 300, and 400 mg/L) and fertilizing frequencies (weekly vs. biweekly), in combination with varying plant ages (1-, 2-, and 3-year-old plants). The analysis focused on several variables, including plant height, the number of leaves, fresh and dry biomass, and flowering traits, such as time to bloom, inflorescence length, floret number, floret diameter, and vase life. The leaf nitrate, total nitrogen, and gas exchange parameters were also recorded. The results demonstrate that the plants receiving 100 mg/L PAW-NO₃⁻ exhibited significantly greater plant height, fresh weight, and dry weight than the control (0 mg/L), with a trend toward a higher leaf number. Flowering occurred earlier in the 100 mg/L treatment group, with the first, second, and third inflorescences emerging at 208, 284, and 304 days after treatment, respectively. Additionally, this concentration produced the highest floret number per inflorescence and the longest vase life (12.63 days). Weekly fertilization resulted in more pronounced vegetative growth than biweekly application, particularly in 3-year-old plants—the only group to flower. Fertilizing frequency, however, had no effect on flower quality regarding the inflorescence length, floret number, or floret size. These findings suggest that 100 mg/L nitrate from plasma-activated water, applied weekly, optimally enhances growth and flowering performance in Vanda orchids.

A field experiment was conducted 2010 cropping season at the Institute for Agricultural Research Farm, Samaru, (11 0 , 11' N, 07 0 38'E). Experimental site was 686 m above sea level in the northern Guinea savanna ecological zone of Nigeria. Study focused on to assess the effects of poultry manure rates (0, 4, 8 and 12 t ha-1) and seedling age (2, 3 and 4 weeks after sowing) at transplanting on growth and yield of amaranth (Amaranthus caudatus L.). Treatments consisted of factorial combinations of four levels of poultry manure and three transplant ages in a randomized complete block design (RCBD) with three replicates. Results indicated that plant height (cm), shoot fresh weight (kg) and number of leaves and branches per plant were significantly (P<0.05) higher with the application of 8 t ha-1 of poultry manure compared with no-manure than the other treatments. However, in most cases, the difference in growth characters using poultry manure rates varying from 4 to 12 t ha-1 were non-significant. Seedlings transplanted at 4 weeks of age were significant taller with shoot fresh weight than 2-weeks old seedlings at the initial growth stage. Transplant age had no effect on these parameters at later stage. All the other growth parameters were not affected (P<0.05) by transplant age. Study suggested that marketable yield increased significantly with increasing poultry manure (4 t ha-1) with transplanting age (2-3 weeks) after emergence to benefit farmers the highest.