Abstract
Although control of xylem ion loading is essential to confer salinity stress tolerance, specific details behind this process remain elusive. In this work, we compared the kinetics of xylem ...Na+ and K+ loading between two halophytes (Atriplex lentiformis and quinoa) and two glycophyte (pea and beans) species, to understand the mechanistic basis of the above process. Halophyte plants had high initial amounts of Na+ in the leaf, even when grown in the absence of the salt stress. This was matched by 7-fold higher xylem sap Na+ concentration compared with glycophyte plants. Upon salinity exposure, the xylem sap Na+ concentration increased rapidly but transiently in halophytes, while in glycophytes this increase was much delayed. Electrophysiological experiments using the microelectrode ion flux measuring technique showed that glycophyte plants tend to re-absorb Na+ back into the stele, thus reducing xylem Na+ load at the early stages of salinity exposure. The halophyte plants, however, were capable to release Na+ even in the presence of high Na+ concentrations in the xylem. The presence of hydrogen peroxide (H2O2) mimicking NaCl stress-induced reactive oxygen species (ROS) accumulation in the root caused a massive Na+ and Ca2+ uptake into the root stele, while triggering a substantial K+ efflux from the cytosol into apoplast in glycophyte but not halophytes species. The peak in H2O2 production was achieved faster in halophytes (30 min vs 4 h) and was attributed to the increased transcript levels of RbohE. Pharmacological data suggested that non-selective cation channels are unlikely to play a major role in ROS-mediated xylem Na+ loading.
Early season foliar fertilization with different nutrients is a promising tool in pomegranate grown in poor, high pH soils. The effects of foliar fertilization with FeSO4 and the synthetic chelate ...Fe(III)-EDDHA (Fe(III)-ethylendiaminedi(o-hydroxyphenylacetate)) on fruit yield and physicochemical characteristics were assessed in a two-season field trial. Fertilizers were sprayed at full bloom and one month later, using Fe concentrations of 1.3 and 2.6 mM for FeSO4 and 1.1 and 2.1 mM for the Fe-chelate. Both doses of FeSO4 and the higher chelate dose increased leaf Fe concentrations and fruit yield, with the best results being observed with 2.6 mM FeSO4 (20–31% increases in yield). On the other hand, leaf N, P, K, Ca, and Mn concentrations were not affected by foliar Fe fertilization. The only treatment that increased the number of fruits per tree, aril juice content and juice total soluble solids and decreased juice total acidity in both seasons was 2.6 mM FeSO4. Both FeSO4 doses caused consistent increases in the maturity index and total sugars in juice, along with minor decreases in juice total phenolic compounds. The antioxidant activity in juice was slightly decreased by 2.6 mM FeSO4. In conclusion, early season foliar Fe fertilization had positive effects on pomegranate yield and quality, with FeSO4 being better than Fe(III)-EDDHA.
•A single foliar spray with relatively low amounts of B or Zn nano-fertilizers (34mgBtree−1 or 636mgZntree−1, respectively) led to increases in pomegranate fruit yield.•Fertilization with the highest ...of the two doses led to significant improvements in fruit quality, including TSS, decreases in TA, and increases in maturity index and pH in juice.•Physical fruit characteristics were unaffected. Changes in total sugars and total phenolic compounds were only minor, whereas the antioxidant activity and total anthocyanin were unaffected.
This study was carried out to assess the effects of the foliar application of nano-fertilizers of zinc (Zn) and boron (B) on pomegranate (Punica granatum cv. Ardestani) fruit yield and quality. A factorial experiment was conducted based on a completely randomized block design, with nine treatments and four replications per treatment. Foliar sprays of nano-Zn chelate fertiliser at three concentrations (0, 60 and 120mgZnL−1) and nano-B chelate fertiliser (0, 3.25 and 6.5mgBL−1) were applied as a single spray before full bloom at a rate of 5.3Ltree−1. The application of Zn and B increased the leaf concentrations of both microelements in August, reflecting the improvements in tree nutrient status. A single foliar spray with relatively low amounts of B or Zn nano-fertilizers (34mgBtree−1 or 636mgZntree−1, respectively) led to increases in pomegranate fruit yield, and this was mainly due to increases in the number of fruits per tree. The effect was not as large with Zn as with B. Fertilization with the highest of the two doses led to significant improvements in fruit quality, including 4.4–7.6% increases in TSS, 9.5–29.1% decreases in TA, 20.6–46.1% increases in maturity index and 0.28–0.62pH unit increases in juice pH, whereas physical fruit characteristics were unaffected. Changes in total sugars and total phenolic compounds were only minor, whereas the antioxidant activity and total anthocyanins were unaffected.
Display omitted
•Few studies have examined the effects of Ca nano-fertilizers on pomegranate fruit yield and quality.•Fruit yield and quality of pomegranate trees have been assessed after two sprays ...with different Ca formulations, including a nano-fertilizer and CaCl2.•Ca foliar fertilization had no effects on pomegranate yield and only small effects on fruit quality.•A positive effect of Ca fertilizers in decrease pomegranate fruit cracking was found.•Low doses of a Ca nano-fertilizer were better than high doses of CaCl2 in reducing pomegranate fruit cracking.
An experiment was conducted to assess the effects of foliar sprays of a calcium fertilizer containing nanoparticles (nano-Ca) and calcium chloride (CaCl2.2H2O) on the yield and quality of pomegranate fruits cv. Ardestani, during two consecutive years, 2014 and 2015. The nano-Ca fertilizer was sprayed at concentrations of 0.25 and 0.50g Ca L−1, and CaCl2.2H2O was used at concentrations of 1 and 2% (2.73 and 5.45g Ca L−1), with treatments being applied twice, first at full blooming and then one month later. Calcium foliar fertilization did not have significant effects on yield, number of fruits per tree and average fruit weight, whereas it increased fruit length only in the case of the CaCl2 1% treatment in the first season. The untreated trees in the orchard were moderately affected by fruit cracking, with 6–7% of the fruits being affected. Calcium foliar treatment with the nano-Ca fertilizer at 0.50g Ca L−1 and 1% CaCl2 (in the both seasons) and also 2% CaCl2 (only in the second season) decreased significantly fruit cracking when compared with the control treatment, resulting in increases in marketable fruit yield. Foliar sprays with CaCl2 1% increased TSS by 7.6% only in the second season. Moreover, foliar nano-Ca fertilization at 0.50g Ca L−1 led to minor decreases (approximately 1%) in total phenolics only in the first season. Other chemical properties, including titratable acidity, fruit maturity, total sugar, antioxidant activity and total anthocyanin contents were not affected by Ca foliar fertilization. Leaf analyses show that Ca foliar treatments increased leaf Ca concentrations in the first season, with the exception of the low dose of nano-fertilizer, whereas the leaf concentrations of N, P, K, Fe, Zn and Mn were unaffected. In summary, fertilization with a low (0.50g Ca L−1) Ca concentration in the form of a nano-Ca formulation resulted in similar decreases in pomegranate fruit cracking than those obtained with higher doses of CaCl2 (2.73 and 5.45g Ca L−1).
PDF
