Co-inoculation of Anabaena cylindrica and Azospirillum brasilense during initial growth and chloroplast pigments of corn

ABSTRACT Although the isolated effects of the cyanobacteria Anabaena cylindrica and the bacteria Azospirillum brasilense are well-known, the co-inoculation of both can promote other benefits to corn plants’ biological nitrogen fixation and growth. The aim was to evaluate the initial growth and chloroplast pigment levels of corn hybrids co-inoculated with A. brasilense and A. cylindrica. The experiment was conducted in greenhouse conditions using the completely randomized design in a factorial scheme 2 × 4 with two hybrids, Balu 184 and Balu 280 Pro, and four inoculation treatments: no inoculation, inoculation of A. cylindrica, inoculation of A. brasilense, and the co-inoculation of A. cylindrica + A. brasilense. Co-inoculation resulted in higher root growth and dry mass of the aerial part in both hybrids; however, the hybrid Balu 280 Pro presented higher responsivity. The co-inoculation of A. brasilense and A. cylindrica increased initial corn growth without altering the photosynthetic pigment levels.

Rootstock-Mediated Genetic Variance in Cadmium Uptake by Juvenile Cacao (Theobroma cacao L.) Genotypes, and Its Effect on Growth and Physiology

Grafting typically offers a shortcut to breed tree orchards throughout a multidimensional space of traits. Despite an overwhelming spectrum of rootstock-mediated effects on scion traits observed across several species, the exact nature and mechanisms underlying the rootstock-mediated effects on scion traits in cacao (Theobroma cacao L.) plants often remain overlooked. Therefore, we aimed to explicitly quantify rootstock-mediated genetic contributions in recombinant juvenile cacao plants across target traits, specifically cadmium (Cd) uptake, and its correlation with growth and physiological traits. Content of chloroplast pigments, fluorescence of chlorophyll a, leaf gas exchange, nutrient uptake, and plant biomass were examined across ungrafted saplings and target rootstock × scion combinations in soils with contrasting levels of Cd. This panel considered a total of 320 progenies from open-pollinated half-sib families and reciprocal full-sib progenies (derived from controlled crosses between the reference genotypes IMC67 and PA121). Both family types were used as rootstocks in grafts with two commercial clones (ICS95 and CCN51) commonly grown in Colombia. A pedigree-based best linear unbiased prediction (A-BLUP) mixed model was implemented to quantify rootstock-mediated narrow-sense heritability (h2) for target traits. A Cd effect measured on rootstocks before grafting was observed in plant biomass, nutrient uptake, and content of chloroplast pigments. After grafting, damage to the Photosystem II (PSII) was also evident in some rootstock × scion combinations. Differences in the specific combining ability for Cd uptake were mostly detected in ungrafted rootstocks, or 2 months after grafting with the clonal CCN51 scion. Moderate rootstock effects (h2> 0.1) were detected before grafting for five growth traits, four nutrient uptake properties, and chlorophylls and carotenoids content (h2 = 0.19, 95% CI 0.05–0.61, r = 0.7). Such rootstock effects faded (h2< 0.1) when rootstock genotypes were examined in soils without Cd, or 4 months after grafting. These results suggest a pervasive genetic conflict between the rootstock and the scion genotypes, involving the triple rootstock × scion × soil interaction when it refers to Cd and nutrient uptake, early growth, and photosynthetic process in juvenile cacao plants. Overall, deepening on these findings will harness early breeding schemes of cacao rootstock genotypes compatible with commercial clonal scions and adapted to soils enriched with toxic levels of Cd.

Changes in Metabolite Patterns During Refrigerated Storage of Lamb's lettuce (Valerianella locusta L. Betcke)

Lamb's lettuce is a popular winter salad, often grown in private vegetable plots, small local farms or in intensive vegetable production. It is usually marketed as a ready-to-eat produce in supermarkets. The aim of the study was to evaluate the changes in biochemical composition and degradation of bioactive compounds during consumer-relevant time of home-grown and store-bought Valerianella locusta “Vit” salad. Primary metabolites, assimilatory pigments as well as secondary metabolites were monitored during 1 week of refrigerated storage. Home-grown lamb's lettuce exhibited highest levels of total sugars, total organic acids, vitamin C, and total phenolic content as well as enhanced levels of most individual phenolic compounds and chloroplast pigments. Locally produced samples of lamb's lettuce also contained high levels of analyzed bioactive components. All samples retained most bioactive components during the entire period of refrigerated storage. The results underline the instability of vitamin C during refrigerated storage of lamb's lettuce and pinpoint this parameter as being the most affected by storage.

Comparative study of silicon and selenium to modulate chloroplast pigments levels, Hill activity, photosynthetic parameters and carbohydrate metabolism under arsenic stress in rice seedlings

Arsenic (As) in groundwater severely harms global economic development by affecting growth and productivity of agricultural crops that causes human health risk. The comparative influence of silicon (Si) and selenium (Se) to modulate pigments levels, photosynthetic parameters using LI-6400XT Portable Photosynthesis System and carbohydrate metabolism under arsenate (As-V) stress in rice cv. MTU-1010 were evaluated. As(V) stress significantly decreased chlorophyll-a (32% on an average), chlorophyll-b (58% on an average), total chlorophyll (46% on an average), fluorescence intensity (31% on an average),, carotene (39% on an average), xanthophyll (33% on an average), Hill activity (47% on an average) and the photosynthetic parameters viz., intercellular-CO2-concentration (52% on an average), net photosynthesis (54% on an average), transpiration rate (36% on an average) and stomatal conductance (38% on an average) in the test seedlings. As(V) + Si treatments enhanced the said parameters more than As(V) + Se treatments in rice seedlings. Sugar contents viz., reducing (85% on an average) and non-reducing sugar (61% on an average) were increased but starch content (57% on an average) was decreased in As(V) treated seedlings. The activities of carbohydrate metabolizing enzymes were increased, while sucrose synthase activity was decreased due to As(V) toxicity in the test seedlings. Co-application of Si and As(V) as well as Se and As(V) showed ameliorative effects on the said parameters but more potential effect was observed under combined application of Si and As(V) in rice seedlings. Thus, the present study is focused to highlight the comparative capability of Si and Se to ameliorate the As induced toxic effects on chloroplast pigments, photosynthetic activities and sugar metabolism in rice seedlings which will be an effective approach to develop possible strategies in As contaminated agricultural soil to improve normal growth and productivity of rice plants.

Response of chloroplast pigments, sugars and phenolics of sweet cherry leaves to chilling

The aim of the present study was to evaluate the effect of post-flowering chilling of sweet cherry (Prunus avium L.) on the content of biochemical parameters in the leaf (chloroplast pigments, sugars and phenolics). The effect of chilling was investigated in two experiments. Potted 2-year-old trees of cv. 'Grace Star' and 'Schneiders' were exposed to one, two or three consecutive overnight chillings at an average air temperature of 4.7 °C (Experiment I), but in the following year only trees of 'Grace Star' were chilled at 2.2 °C (Experiment II), 3 to 7 weeks after flowering. The analysis of the biochemical parameters was performed by high performance liquid chromatography combined with electrospray ionization mass spectrometry. Chilling at 4.7 °C caused little or no stress, while 2.2 °C induced more intense stress with increased zeaxanthin, sugar and phenolic content in leaves, while exposure of trees to higher temperatures and closer to flowering showed no changes. Two or three consecutive overnight chilling periods increased the phenolic content and enhanced the accumulation of zeaxanthin in the leaves. Sucrose, sorbitol, fructose, total sugar, and total flavonoid content in leaves increased within 48 h after chilling. Zeaxanthin epoxidized within 24 h after one and 48 h after one and two consecutive overnight chillings.

Chloroplast pigments and photochemical efficiency of West Indian cherry under salt stress and potassium-phosphorus fertilization

The objective of this study was to evaluate chloroplast pigments and photochemical efficiency of West Indian cherry cv. BRS 366 Jaburu as a function of irrigation water salinity and potassium-phosphorus fertilization combinations in the second year of cultivation. The experiment was carried out in a protected environment in Campina Grande, Brazil. Treatments were distributed in randomized blocks, in a 5 × 4 factorial scheme, corresponding to five levels of electrical conductivity of irrigation water ECw (0.6, 1.4, 2.2, 3.0 and 3.8 dS m-1) and four combinations of potassium-phosphorus fertilization (100/100, 85/85, 60/60 and 45/45% of the K2O/P2O5 recommendation for the second year of cultivation 200 g of K2O and 120 g of P2O5 per plant per year) with three replicates. Irrigation with saline waters hampered the biosynthesis of chloroplast pigments and the photochemical efficiency of West Indian cherry cv. BRS 366 Jaburu in the second year of cultivation. Water salinity from 2.6 dS m-1 reduced the maximum fluorescence, variable fluorescence, and quantum efficiency of photosystem II of West Indian cherry plants cv. BRS 366 Jaburu. Fertilization with 60/60 and 85/85% of the K2O/P2O5 recommendation promotes an increase in the synthesis of chlorophylls a and b, respectively, in the first and second production cycles of the second year of cultivation. Supply of 85/85% of the K2O/P2O5 recommendation promoted an increase in maximum and variable fluorescence in plants subjected to water salinities of 0.6, 2.2, and 3.8 dS m-1 in the second cycle and reduced the initial fluorescence, regardless of the salinity level in the first and second production cycles of West Indian cherry.

INFLUENCE OF ROOTSTOCKS AND THE TIME OF GRAFTING PROCEDURE ON THE EFFICIENCY OF PROPAGATION BY GRAFTING TWO CULTIVARS OF MOUNTAIN PINE (Pinus mugo Turra) AND ESTIMATION OF CHLOROPLAST PIGMENTS LEVEL IN THE NEEDLES

The experimental studies were conducted from 2015–2017 years in two cycles. The aim of the research was to determine a better grafting time and a choice of an appropriate rootstock for the propagation of two cultivars of mountain pine (Pinus mugo Turra). The influence of the grafted cultivar and rootstock used on the level of chloroplast pigments in the needles was also checked. The studies concerned two cultivars of mountain pine (Pinus mugo) ‘Grześ’ and ‘Zundert’, which were grafted on four different rootstocks: Pinus contorta (Dougl. ex Loud.), Pinus nigra (Arn.), Pinus sylvestris (L.) and Pinus mugo subsp. uncinata (Ramond Domin) in two dates: 20 January and 15 March. The highest percentage of graft success was obtained for the two cultivars on Pinus uncinata and Pinus contorta rootstocks. A later term of grafting procedure affected bigger effectiveness of grafting of the two studied cultivars, except for the graft success on Pinus sylvestris rootstock. The highest increments of side shoots and lengths of main stems for ‘Grześ’ cultivar were obtained on Pinus nigra, and for ‘Zundert’ the influence of the rootstock on the above mentioned parameters was not evident. No significant differences in the number of increments in the first and second year of studies were observed. The highest level of chlorophyll A and B was found in the needles of ‘Grześ’ cultivar, independently from the rootstock used. Among tested rootstocks, only Pinus nigra had a significant impact on a higher content of chlorophyll B in the needles of the studied cultivars of mountain pine trees.