Effect of phosphorus concentration on the photochemical stability of PSII and CO2 assimilation in Pistacia vera L. and Pistacia atlantica Desf.

A greenhouse pot experiment was conducted at the faculty of sciences of Gafsa to evaluate the effect of phosphorus treatment on two pistachio species. The seedlings of Pistacia vera and Pistacia atlantica were subjected to six levels of phosphoric acid (P2O5) (0, 5, 15, 30, 60 and 120 ppm). Stomatal conductance, net photosynthesis, chlorophyll fluorescence (OJIP) and total chlorophyll content were measured after 1, 2, 3, 6, 8, 9 and 12 weeks of treatment. During the experiment, phosphorus application at 5 ppm increased photosynthesis and stomatal conductance, relative to the treatment 0 ppm only in P. atlantica. However, phosphorus supply at 60 and 120 ppm induced toxicity leading to an inhibition of CO2 photo-assimilation rate, an alteration of photosystem II (PSII) structure and function and reduction in leaf chlorophyll content in both species. The (OJIP) transient showed complex changes in O-J, J-I and I-P phases of fluorescence. Due to phosphorus toxicity, both donor and acceptor sides of PSII were damaged, electron transport perturbed and chlorophyll pigment reduced which resulted in the fall of CO2 photo-assimilation rate, followed by mortality in both species.

Seasonal variation and gender pattern of phenolic and flavonoid contents in Pistacia chinensis Bunge inflorescences and leaves.

Pistacia chinensis Bunge (P. chinensis) is a deciduous and dioecious perennial arbor of the family Anacardiaceae that flowers from March to April and bears fruit from September to October. There are three rapidly growing stages in the annual growth process of P. chinensis. However, the knowledge of the secondary metabolites related to P. chinensis gender and growth season remains scant. In this study, HPLC was used to qualitatively and quantitatively determine the content of the catechin hydrate, rutin, quercetin, and kaempferol contents in male and female tree inflorescences and leaves. Total phenolics and flavonoids were also detected using a spectrophotometer. The results indicated that the contents of these compounds fluctuated with seasons and they reached the highest levels in nascent leaves. The fluctuations of these compounds followed different pathways of evolution, by increasing or decreasing in male and female trees throughout the whole growth process because they had their own biological functions. Moreover, the extracts exhibited DPPH radical scavenging bioactivity and showed no significant cytotoxicity towards 3T3-L1 preadipocytes. Together, these results demonstrated that P. chinensis has great potential as an antioxidant medicine, and the best harvest time is in the spring.

Arsenic- and mercury-induced phytotoxicity in the Mediterranean shrubs Pistacia lentiscus and Tamarix gallica grown in hydroponic culture.

Hg and As resistance and bioaccumulation were studied in hydroponically grown Pistacia lentiscus and Tamarix gallica plants. Both elements caused growth inhibition in roots and shoots, with mercury showing greater phytotoxicity than arsenic. Accumulation of both elements by plants increased in response to element supply, with the greatest uptake found in T. gallica. Both elements affected P and Mn status in plants, reduced chlorophyll a concentration and increased MDA and thiol levels. These stress indices showed good correlations with As and Hg concentration in plant tissues, especially in the roots. Toxic responses to mercury were more evident than for arsenic, especially in shoot tissues. T. gallica showed higher resistance to both Hg and As than P. lentiscus, as well accumulating more As and Hg.