Roselle (Hibiscus sabdariffa L.) plant is a valuable medicinal crop in arid and semi-arid regions. The use of microbes as bio-fertilizers in enhancing crop production is more favorable than chemical fertilizers due to food safety. A pot experiment was conducted to explore the effect of Azotobacter chroococcum and Azospirillum brasiliense as a bio-fertilizer on the growth, yield, and quietly of roselle plants. Roselle seeds were mixed with the tested biofertilizer and cultivated on plastic pots filled with a sandy clay loam soil. The bio-fertilization significantly (p0.05) increased the growth, nutrients uptake, yield, and quality of roselle plants compared to the untreated plants. The inoculation of roselle plants with the bio-fertilizer increased the total chlorophyll, carotenoid, total anthocyanin (TAC), and total flavonel (TF) by 16.45, 26.10, 8.44, and 14.27%, respectively, above the control. The bio-fertilization increased the soil available nitrogen by 14.33% above the control, and increased the uptake of N, P, and K by 18.8, 17.81, and 12.75%. The biofertilization not only increased the quality of roselle plants but also increased the fresh and dry weights of sepals yield by 5.89 and 3.55%, respectively.

Adequate amount of essential plant nutrients and plant density are vital factors influencing the productivity of oilseed rape (Brassica napus L.). Field experiments were conducted in southern China to study the influence of different fertilizing levels and planting densities on the seed yield, chlorophyll content and some growth traits of winter oilseed rape. Five fertilizing levels and six planting densities were set in a randomized block design. The tested planting densities were D1, D2, D3, D4, D5 and D6 with 7.5 × 104 , 15 × 104 , 22.5 × 104 , 30 × 104 , 37.5 × 104 and 45 × 104 plants ha−1 , respectively. The tested fertilizing levels were F0 (control without fertilization), F1 (N = 60, P2O5 = 30, K2O = 52.5, S = 3.75, B =0.3 kg ha−1 ), F2 (N = 120, P2O5 = 60, K2O = 105, S = 7.50, B =0.60 kg ha−1 ), F3 (N = 180, P2O5 = 90, K2O = 157.5, S = 11.25, B =0.90 kg ha−1 ) and F4 (N = 240, P2O5 = 120, K2O = 210, S = 15, B =1.20 kg ha−1 ). The results showed that there were close relationships between the seed yield and fertilizing levels × planting densities. Below the fertilization level of F2, the seed yield increased as the planting density increased. Application of F3 caused a seed yield decline when the planting density surpassed 37.5 × 104 plants ha−1 . The tested fertilizing levels caused remarkable increases in the seed yield but the plant density had little effects. The highest seed yield (2487 kg ha−1 ) was recorded in F4D3 followed by F4D1 (2308 kg ha−1 ), F4D5 (2303 kg ha−1 ) and F3D6 (2302 kg ha−1 ); while the minimum yield was obtained from the unfertilized soil treatments. The current research paper highlighted the importance of balanced N, P, K, S and B application under the different plant densities in winter oilseed rape. The individual growth of plants compensated the low plant density, but increasing the fertilization rates caused remarkable increases in the oilseed rape, suggesting that optimum nutrients rates are a critical factor in seed yield production.

Sweet basil (Ocimum basilicum var. Genovese) is an important medicinal herb and is considered to be a moderately salt-tolerant plant. However, little is known about the effect of biochar on enhancing its salinity tolerance. The response of basil plant to water salinity (8 dS m

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