Inorganic solute accumulation in noni (Morinda citrifolia Linn) under salt stress during initial growth

Abstract

Noni (Morinda citrifolia) is a fruit species which is well adapted to different soil and climate conditions, and may be a good option for farmers in arid and semi-arid regions. To evaluate the tolerance of noni plant in the initial phase to salinity and the accumulation of inorganic solutes in its organs, an experiment was carried out in a greenhouse under hydroponic system. The experimental design was completely randomized, with five levels of NaCl (0, 25, 50, 75 or 100 mM) in the nutrient solution, and four replicates. Plant height, stem diameter, number of leaves, dry matter of leaves, stems and roots, leaf area, leaf succulence, sclerophylly index and the contents of Na + , Cl -and K + in different plant organs were evaluated after 40 days of stress. Salinity reduced the growth of all plant organs in the initial phase, in contrast, leaf succulence and sclerophylly index increased by 32% at the highest saline level, compared with control plants. The contents of Na + and Cl -in leaves, stems and roots increased, while K + contents decreased with the increment in salinity. The highest K + contents were observed in the roots and the highest Na + and Cl -contents were observed in the leaves. Salinity induced disturbances in the ionic homeostasis of noni plants, which can explain, at least in part, the saltinduced growth reduction.

Use of hydrogen peroxide in acclimation of basil (Ocimum basilicum L.) to salt stress

“…T1 T2 T3 T4 T5 T6 T1 T2 T3 T4 T1 T2 T3 T4 T5 T6 T1 T2 T3 T4 T1 T2 T3 T4 T5 T6 T1 T2 T3 T4 T1 T2 T3 T4 T5 T6 15 days 25 days 15 days 25 induced decrease in K + content was reported by other authors (Gondim et al, 2011;Cova et al, 2016). This reduction is related to the antagonism between these two ions, since Na + ions uptake by root cells occurs through nonselective K + channels and high affinity K + transporters due to physicochemical similarities between Na + and K + (Gondim et al, 2011;Miranda et al, 2017).…”

“…At 25 days, T1 and T2 treatments were not different, but an increase of about 31% was observed in the SUC of plants acclimated with H 2 O 2 ( Figure 1E), suggesting that the plants under these treatments maintained a greater cell water status, reducing saltinduced water stress. Cova et al (2016) reported that salinity induced an increase of SUC in noni (Morinda citrifolia Linn) leaves after 40 days of salt stress. According to these authors, plants under salt stress or other abiotic stress may present such mechanisms to survive adverse environmental conditions.…”

“…SI can be considered as a physiological trait in response to stress conditions, such as salinity. Therefore, this increase in SI indicates a higher leaf thickness, with more layers of photosynthetic tissues, which may be an important factor to reduce the deleterious effects of salinity on plant growth (Cova et al, 2016).…”

“…The plant material was then oven dried at 65 °C for 72 h for determination of the leaf (LDM), stem (SDM), and shoot dry mass (SHDM). From the data of LFM, LDM, and LA, the leaf succulence (SUC) and sclerophylly index (SI) were calculated, as described by Cova et al (2016).…”

“…Salinity is one of the major challenges for crop production, especially in semiarid regions such as the Northeast of Brazil (Cova et al, 2016). In this region, the excessive use of fertilizer, lack of drainage, and low quality of irrigation water are considered the main factors contributing to soil salinization (Niu and Cabrera, 2010).…”