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The purpose of this study was to assess the possible protective role of exogenous salicylic acid (SA), sodium nitroprusside (SNP), a donor of nitric oxide, and their combination on 21-day-old safflower (Carthamus tinctorius L.) seedlings grown under zinc (Zn) stress. The results revealed that exposure to 500 µM ZnSO.7HO for 10 days markedly reduced the root and shoot dry weights in Zn-treated plants, while the application of SA, SNP and specially SA + SNP significantly increased the root and shoot dry weights in seedlings subjected to Zn stress. Addition of SA, SNP and SA + SNP interestingly reduced root-to-shoot translocation of zinc and increased significantly the level of glutathione (GSH) and ascorbate (ASC) in leaves of Zn-stressed plants. The Zn-treated plants supplemented with SA and SNP revealed an improved activity of ascorbate-glutathione cycle enzymes and those enzymes which are involved in glyoxalase system as compared to the plants treated with Zn only. However, no significant relationship was found between SA or SNP supplementation and glutathione S-transferase activity in Zn-stressed plants. These findings demonstrate that exogenous application of SA or SNP could ameliorate the negative effects of Zn on safflower plants probably by stimulation of antioxidant defense and glyoxalase systems.

Cellulose nanofiber (CNF) was used to improve the optical and strength properties of soda bagasse pulp (500 CSF) in the presence of cationic polyacrylamide (CPAM). Cationic polyacrylamide was added at 0.05, 0.1, and 0.15%, and cellulose nanofiber was added at 0.1, 0.5, 1, and 2% based on pulp O.D. Laboratory handsheets were prepared (60 g/m 2 ), and optical and strength properties were measured according to TAPPI standards. Scanning electron microscopy and atomic force microscopy images showed that empty spaces between fibers decreased under CPAM/CNF treatments. The effect of the additives and their addition level on all the measured paper properties was significant at the 99% confidence level. The light scattering coefficient, brightness, and whiteness increased with the addition of cellulose nanofibers, but the light absorption coefficient, yellowness, and opacity decreased. At the highest levels of the additives (2% CNF and 0.15% CPAM), the tensile and burst strengths of handsheets increased by 33% and 15%, respectively. Generally, cellulose nanofibers/cationic polyacrylamide complexes improved the optical and strength properties of bagasse pulp.

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