Leaf Tissue Concentrations Research Articles

Integrated stress responses in okra plants (cv. ‘’Meya’]: unravelling the mechanisms underlying drought and nematode co-occurrence

BackgroundClimate change threatens sub-Saharan Africa’s agricultural production, causing abiotic and biotic stressors. The study of plant responses to joint stressors is crucial for understanding molecular processes and identifying resilient crops for global food security. This study aimed to explore the shared and tailored responses of okra plants (cv. ‘’Meya’), at the biochemical and molecular levels, subjected to combined stresses of drought and Meloidogyne incognita infection.DesignThe study involved 240 okra plants in a completely randomized design, with six treatments replicated 20 times. Okra plants were adequately irrigated at the end of every 10-days water deficit that lasted for 66 days (D). Also, the plants were infected with M. incognita for 66 days and irrigated at 2-days intervals (R). The stresses were done independently, in sequential combination (D before R and R before D) and concurrently (R and D). All biochemical and antioxidant enzyme assays were carried out following standard procedures.ResultsSignificant reductions in leaf relative water content were recorded in all stressed plants, especially in leaves of plants under individual drought stress (D) (41.6%) and plants stressed with root-knot nematode infection before drought stress (RBD) (41.4%). Malondialdehyde contents in leaf tissues from plants in D, nematode-only stress (RKN), drought stress before root-knot nematode infection (DBR), RBD, and concurrent drought-nematode stress (RAD) significantly increased by 320.2%, 152.9%, 186.5%, 283.7%, and 109.6%, respectively. Plants in D exhibited the highest superoxide dismutase activities in leaf (147.1% increase) and root (105.8% increase) tissues. Catalase (CAT) activities were significantly increased only in leaves of plants in D (90.8%) and RBD (88.9%), while only roots of plants in D exhibited a substantially higher CAT activity (139.3% increase) in comparison to controlled plants. Okra plants over-expressed NCED3 and under-expressed Me3 genes in leaf tissues. The NCED3 gene was overexpressed in roots from all treatments, while CYP707A3 was under-expressed only in roots of plants in RBD and RKN. CYP707A3 and NCED3 were grouped as closely related genes, while members of the Me3 genes were clustered into a separate group.ConclusionThe biochemical and molecular responses observed in okra plants (cv. ‘’Meya’) subjected to combined stresses of drought and Meloidogyne incognita infection provide valuable insights into enhancing crop resilience under multifaceted stress conditions, particularly relevant for agricultural practices in sub-Saharan Africa facing increasing climatic challenges.

Iron and Manganese concentrations in leaf tissues of Rhizophora mangle (Rhizophoraceae): implications for energetic metabolism

Introduction: Iron (Fe) and manganese (Mn) are bioessential micronutrients for plants but can impair the energetic metabolism when present at high levels. Objective: To assess the photosynthetic performance and oxidative damages in Rhizophora mangle L. leaf tissues at low and high concentrations of Fe (74 and 195 mg kg-1; Feleaf) and Mn (65 and 414 mg kg-1; Mnleaf). Methods: Photosynthetic pigments, chlorophyll a fluorescence, leaf CO2 assimilation and gas exchange and DPPH• radical scavenging capacity were sampled in R. mangle growing in estuarine forests in the North region of Espírito Santo State and the extreme South of Bahia State (Brazil) showing low and high Feleaf and Mnleaf. Results: Effects of high Fe and Mn were not identified on pigment levels. The increase in Feleaf and Mnleaf at the levels observed in this assessment had a positive effect on the number of reaction centers and on the efficiency of the oxygen-evolving complex, evaluated as K-band, while no changes were found in the parameters related to the excitation trapping efficiency at the active center of photosystem II. Distinct interference patterns of Fe and Mn on the functional processes of photosynthesis were identified, especially on CO2 assimilation and reactive oxygen species metabolism, with major effects on CO2 assimilation and carboxylation efficiency of Rubisco at high Mnleaf. Conclusion: These findings demonstrate the efficiency of R. mangle in positively regulating the electron transport chain in response to high Fe and Mn, at least in terms of the preservation of structure and functionality of the plant photosynthetic apparatus. Moreover, interference of high Mnleaf in R. mangle occurs at non-stomatal and biochemical levels. There is an antagonistic interference of these trace elements with the physiology of R. mangle, which is a dominant species in Brazilian mangroves.

Coleus cultivars nutritional status as a function of leaf coloration

Sixteen coleus (Coleus scutellarioides) cultivars (genotypes) with four cultivars representing four industry-categorized color groups [phenotypes (Burgundy, Orange, Red, and Yellow/Green)] were evaluated to determine if leaf color affected tissue nutrient concentrations. Plants were grown at two locations provided with a liquid fertilizer concentration of 150 mg.L−1 N delivered from 17 N–1.31P–14.1K. Leaf tissue samples were collected and analyzed for the concentration of 12 elemental nutrients after eight or 10 wk of growth, depending on location. Leaf tissue nutrient concentrations were influenced by leaf color (color groups), but the magnitude varied for each elemental nutrient. Leaf tissue nutrient concentrations were significantly different for each color group for phorphorus (P), potassium (K), calcium, magnesium, iron, copper and boron, but not for nitrogen, sulfur, manganese, or zinc. Trends for higher P and K leaf tissue concentrations in Red-leaf coleus cultivars, and lower P in Yellow/Green cultivars agree with prior work reported for Heuchera sp. This data further support the initial foundational work to determine the relationship between leaf color and tissue nutrient concentration. Further investigations among other species may offer additional data that will help establish a relative relationship between an element and phenotypes. Given the wide variation in leaf tissue concentrations across all 16 cultivars, an overall consolidated data set was developed to provide a refinement of the leaf tissue nutrient standards for coleus across all elements. This expands the recommended ranges available for interpreting leaf tissue samples, which will assist growers and crop advisors in diagnosing nutrient disorders of coleus.

Mineral composition and chlorophyll fluorescence in cowpea plants amended with bulk and nanoparticles of Zn and Cu oxides

Zinc oxide (ZnO-NP) and copper (CuO-NP) nanoparticles have been proposed for crop fertilization, but studies demonstrating their efficiencies and evaluating their phytotoxicities compared to bulk sources are still scarce. Here, we assessed the dissolution of Zn and Cu oxides of nanoparticulate and bulk sources and their effects on cowpea’s biomass, nutritional status, and photosynthetic apparatus. The results showed that Zn and Cu dissolution rate and release from nanoparticulate oxides were higher than bulk oxides. Regardless of the source, the addition of Zn and Cu concentrations to the solution increased the root, stem, and leaf tissue concentrations of these micronutrients and reduced the contents of nutrients and pigments, with consequent inhibition of photosynthesis as indicated by the parameters of chlorophyll fluorescence. Except for the lowest rate of the sources tested, biomass was reduced due to metal toxicity. However, biomass decreasing was not related to the source itself but to the nanoparticle source higher solubility, which promoted higher phytotoxicity.

Seasonality strongly affects short‐term C‐storage in coastal macrophyte communities

AbstractEcosystem functions provided by aquatic plants are context dependent and mediated by environmental conditions and plant growth form. This impedes our ability to predict the carbon (i.e., C) sink potential of multispecies coastal meadows characterized by marked seasonal succession of environmental conditions, causing a clear need to explore the distinct patterns of both C capture and release associated with seasonal succession of macrophyte growth forms and life‐history strategies in aquatic plant communities. We conducted four field surveys throughout 2022–2023 (i.e., October, March, June, and August), where we sampled six soft bottom locations dominated by aquatic vascular plants in the northern Baltic Sea. Temporal differences in biomass‐bound C stocks (i.e., structural elements and non‐structural carbohydrates) were linked to the plant production‐decomposition cycle and peaked when environmental conditions became increasingly permissive for growth and development (i.e., summer). Species identity influenced seasonal patterns of non‐structural carbohydrate concentrations in both leaf and rhizome tissue by shaping the timing of short‐term accumulation (i.e., photosynthesis) of C in plant tissue or release through respiration. Overall, our study illustrates that biomass‐bound C stocks were shaped by both seasonality and the variation of functional structure and life history strategies found within the vegetated seascapes. This highlights the importance of addressing both biodiversity and short‐term C dynamics and suggests that estimations of C budgets or stock assessments should be based on data incorporating the intra‐annual variation in C dynamics to fully comprehend the C sink potential of vegetated seascapes.

Yield sustainability through micronutrient management in Guava

A field study conducted with soil and foliar application of ZnSO4 and borax at different phenological stages of guava cv. Shewta in sandy loam soil, revealed that highest sustainable yield index (0.80) was recorded with two sprays of 0.4% ZnSO4 + 0.2% borax during fruit growth at one month interval, followed by 0.63 with three sprays of 0.4% ZnSO4 + 0.2% borax before flowering, fruit set and during fruit growth. Highest TSS (13.13°Brix), acidity (0.652%) and ascorbic acid (262.21 mg/100 g) was recorded in two sprays of 0.4% ZnSO4 + 0.2% borax at fruit growth in one month interval. Significant differences in Zn and B content in guava fruit pulp was recorded. It was noted that Guava fruit pulp had Zn content of 13.7 mg kg-1 in control tree fruits while 14.6 to 16.5 mg kg-1 in treated trees. Moreover, guava fruit pulp enriched with B (14.3 to 17.3 mg kg-1) in treated tree fruits as compared to 12.4 mg kg-1 in control trees. Micronutrient contents in leaf tissues showed significant difference in Zn and B concentration, whereas, Fe, Mn and Cu contents were statistically non-significant. The index suggested for attaining the sustainability and to economize the nutrient application, technology package consisting of two sprays of 0.4% ZnSO4 and 0.2% borax during fruit growth at one month interval should be adopted at growers’ field.

Aplicações de gesso e calcário melhoram a fertilidade do solo sob cultivo de coco na Amazônia Oriental, Brasil

ABSTRACT Gypsum and lime application causes chemical modifications in the soil that influence nutrient content, root growth and development of plants. An experiment was carried out in the municipality of Santa Isabel, Pará state, Brazil, to evaluate the chemical changes in the soil and the responses of green dwarf coconut to gypsum and lime at 6 and 12 months after application. The experimental design was completely randomized blocks, with 4 blocks and 7 treatments: T1 = control; T2 = 2000 kg ha-1 lime; T3 = 500 kg ha-1 gypsum; T4 = 2000 kg ha-1 lime + 300 kg ha-1 gypsum; T5 = 2000 kg ha-1 lime + 500 kg ha-1 gypsum; T6 = 2000 kg ha-1 lime + 700 kg ha-1 gypsum; T7 = 2000 kg ha-1 lime and 1000 kg ha-1 gypsum. After 12 months of applying the treatments, the combination of gypsum and limestone was used to reduce aluminum saturation, with values of 0% at a depth of 0.0-10 cm of the soil, as well as increments in sulfur contents and base saturation of the soil, with values of 70% at a depth of 0.0-10 cm of the soil; with positive effects on macronutrients concentrations in leaf tissue and on root growth. Application of agricultural gypsum, associated with lime, is efficient to improve the chemical attributes of the soil and the development of green dwarf coconut plants.

Assessment of physiological and biochemical responses of chilli (Capsicum annuum) varieties in floating bed cultivation for adaptation to waterlogged areas of Bangladesh.

Chilli (Capsicum annuum ) is an important spice crop in Bangladesh. This crop is very sensitive to waterlogging. Floating agriculture is an innovative system led by the local people of the southern region of Bangladesh, in which seedlings of vegetables are produced in low-lying areas using different aquatic macrophytes. An experiment was carried out to evaluate the viability of chilli cultivation in waterlogged areas, based on physiological and biochemical responses using floating agriculture. Eight different chilli varieties were subjected to floating agriculture in two different agronomic seasons. A soil-based chilli cultivation system was also trialled, to compare the utility of this method. To evaluate the performance of chilli in floating beds, plant water status, photosynthetic parameters, and leaf tissue concentrations of Na+ , K+ , NO3 - and PO4 3- , chlorophyll, ascorbic acid and proline were assessed. This study shows that macrophytes utilised in floating beds provide favourable conditions for chilli cultivation under waterlogged conditions. Among the different varieties, Sakata 653 in summer and Jhilik in winter responded better than others. As the performance of chilli in the floating agriculture system was satisfactory in comparison with soil-based cultivation, floating agriculture can be an alternative agronomic method for chilli cultivation in waterlogged areas of Bangladesh.

The Growth, Leaf Antioxidant Enzymes and Amino Acid Content of Tomato as Affected by Grafting on Wild Tomato Rootstocks 1 (S. Pimpinellifolium and S. Habrochaites) Under Salt Stress

Salinity in soil or water is a serious threat to plant growth, which reduces yields and threatens food security. It is possible to reduce the negative effects of salinity on tomato scions through grafting. To evaluate the effects of salt stress on graft combinations in hydroponic conditions, SP3, SP4, SP5 (S. pimpinellifolium), SH1, SH3, SH5 (S. habrochaites) and two hybrids L × SP5 (S. lycopersicum L. × S. pimpinellifolium) and L × SH3 (S. lycopersicum L. × S. habrochaites) were used as rootstock and two varieties Galaxy and H2274 (S. lycopersicum L.) were used as scion. Plants were evaluated in terms of biomass parameters and antioxidant enzyme activities and amino acid contents in leaf tissues under control and salt stress conditions. Salt stress decreased the fresh weight of shoots and roots by 68.71 and 23.59, respectively, and increased H2O2 content (93.90 %) and MDA content (63.71 %). In addition, salt stress in leaf tissues POD (204.49 %), CAT (83.87 %), SOD (204.49 %), GR (88.23 %), GST (100.16 %), G6PD (32.85 %), 6GPD (46.19 %), APX (157.29 %) caused an increase in enzymes and total amino acid content (160.57 %). In salt stress conditions, SH5/Galaxy and L × SP5/Galaxy are the graft combinations with the highest fresh shoot and root weight, leaf number and root volume. These graft combinations contain the most isoleucine, proline lysine, alanine arginine, sucrosine leucine, methionine, hydroxyproline glutamate, glutamine and histidine amino acids in leaf tissues and have the lowest MDA content. Ungrafted H2274 and Galaxy plants have the highest MDA and content under salt stress conditions, these ungrafted plants have the least other amino acids and enzymes other than theonine amino acid in their leaf tissues. Furthermore, ungrafted plants under saline conditions had the lowest shoot and root fresh weight, leaf number and root volume. MDA content correlated negatively with shoot and root fresh weight, leaf number and root volume. H2O2 correlated positively with CAT, SOD, GST and peroxidase enzymes and negatively with APX, GR and G6PD enzymes. It seems that the antioxidant enzyme activity and amino acid content in leaf tissues influence salinity response and the appropriate rootstock/scion combination could be a viable method for tomato cultivation in saline conditions.

Preharvest melatonin application mitigates arsenic-induced oxidative stress and improves vase life of tuberose (Polianthes tuberosa L.) cut flowers

Arsenic (As) stress severely hinders the growth of ornamental cut flowers. Melatonin (MLT) as a biostimulant protects plants from various abiotic stresses including As stress. However, its protective roles are not well understood in ornamental cut flowers especially tuberose. This research investigated the effects of exogenous melatonin supplementation on alleviating As stress damage in tuberose plants. In As-treated plants, growth traits and leaf chlorophyll contents markedly decreased, while application of MLT, alleviated the inhibitory effect of As on plant growth and chlorophyll content in As-treated plants. Melatonin application considerably increased the vase life of cut tuberose flowers and also improved the protein as well as proline contents in leaf tissues. Level of oxidative markers including electrolyte leakage (EL), malondialdehyde (MDA) and hydrogen peroxide (H2O2) increased in As-treated plants. Upon application of MLT, this trend was alleviated; however, the activities of enzymatic antioxidants increased when plants were subjected to As stress in combination with MLT. Results obtained in the present study suggest that exogenous MLT could alleviate negative effects of As stress on tuberose plants stimulating of oxidative defense related antioxidants. These results are beneficial to improve ornamental tuberose cut flowers production in heavy metal polluted soils or irrigation water.

The damage caused by Cd toxicity to photosynthesis, cellular ultrastructure, antioxidant metabolism, and gene expression in young cacao plants are mitigated by high Mn doses in soil.

Manganese (Mn) is one of the essential mineral micronutrients most demanded by cacao. Cadmium (Cd) is highly toxic to plants and other living beings. There are indications that Mn can interact with Cd and mitigate its toxicity. The objective of this study was to evaluate the action of Mn on the toxic effect of Cd in young plants of the CCN 51 cacao genotype, subjected to different doses of Mn, Cd, and Mn+Cd in soil, through physiological, biochemical, molecular, and micromorphological and ultrastructural changes. High soil Mn doses favored the maintenance and performance of adequate photosynthetic processes in cacao. However, high doses of Cd and Mn+Cd in soil promoted damage to photosynthesis, alterations in oxidative metabolism, and the uptake, transport, and accumulation of Cd in roots and leaves. In addition, high Cd concentrations in roots and leaf tissues caused irreversible damage to the cell ultrastructure, compromising cell function and leading to programmed cell death. However, there was a mitigation of Cd toxicity when cacao was grown in soils with low Cd doses and in the presence of Mn. Thus, damage to the root and leaf tissues of cacao caused by Cd uptake from contaminated soils can be attenuated or mitigated by the presence of high Mn doses in soil.

Enhanced chemical and physical defense traits in a rice cultivar showing resistance to leaffolder infestation

The leaffolder (LF), Cnaphalocrocis medinalis, poses a significant threat to rice crops. The larvae feed on rice leaves, damaging both the epidermal and mesophyll tissues, and engage in leaf-folding behaviors to build shelters that can lead to significant yield losses. In this study, we discovered a rice cultivar, P213, that exhibits resistance to LF infestation. When compared to the susceptible cultivar XiuShui11 (XS11), the larvae on P213 exhibited reduced weight and took longer to build their silk-leaf shelters. Through a side-by-side analysis of phytohormones, metabolites and transcriptomes in the two cultivars, we found that jasmonate (JA)-induced defenses are not the main contributors to P213 resistance against LF. Rather, salicylic acid and flavonoids emerge as potential chemical defenses against this insect pest. Furthermore, the resistant cultivar P213 exhibited a greater density of micro hairs and long macro hairs, the latter of which were absent in the susceptible cultivar. The silicon contents in leaf tissues were also more prominent in the resistant cultivar, suggesting that the physical defenses against LF are enhanced in P213. These findings shed new light on the mechanisms of rice resistance to LF and provide a foundation for future research into the genetic basis of this resistance.

Uptake and Retention of Imidacloprid and Cyantraniliprole in Cotton for the Control of Bemisia tabaci (Hemiptera: Aleyrodidae)

Abstract Plant tissue bioassays are a standard approach for bioassaying insects such as the sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), an insect that specializes in systemic feeding on the phloem in leaves by using a piercing-sucking mouthpart apparatus. Systemic insecticides remain the most effective approach to whitefly management; however, little work has been done to quantify the amount of insecticide active ingredient that a species is exposed to when feeding. This study was conducted to estimate the imidacloprid and cyantraniliprole concentrations present in cotton (Gossypium hirsutum L.) leaves 24 h after a root drench for systemic toxicological bioassays. Insecticide active-ingredient quantification involved liquid chromatography–tandem mass spectrometry. Comparable concentration responses also were conducted to indicate the mortality of the sweetpotato whitefly at the tested concentrations. The results indicated significant active-ingredient retention with higher concentrations of insecticide treatments, which corresponded with higher sweetpotato whitefly mortality. Specifically, for imidacloprid and cyantraniliprole, the average slopes and intercepts of the log parts per billion of leaf tissue concentration to milligrams of active ingredient per liter of treatment solution were y = 4.08 x + 0.83 and y = 6.22 x + 0.47, respectively. These formulae estimate leaf tissue concentrations that can be linked to insect insecticide exposure in the leaves, with 50–73% of the overall variability explained. Significant correlations also were observed between the root drench concentrations, leaf tissue concentrations, and sweetpotato whitefly mortality.

Morphological traits and Zn content of several cassava genotypes in nutrient solution culture

Leaf morphological characters and nutrient content in leaf tissue can vary depending on plant genotype. The nutrient solution culture can produce leaves with good nutritional content. Therefore, this research aimed to evaluate and validate cassava putative mutants' morphological traits and Zn content using a nutrient solution culture system. This research was carried out from January to May 2022 at the greenhouse of Cikabayan Experimental Garden, IPB University, Bogor. This study used two cassava cultivars and ten mutant genotypes from the cassava research team of IPB University, resulting from mutation breeding by gamma irradiation. The plant characters observed in this study included the number of leaves, length and width of the leaflet, leaf colour, plant height, fresh and dry weight leaf, and analysis of Zn content. The data were analyzed using ANOVA at a significant level of α = 5%, followed by Tukey's further test. The results showed that the G2D1-422 genotype had a higher Zn content than the wild type (Ratim/G2) and the other genotypes. The high Zn genotypes (G2D1-422) and low Zn genotypes (Ratim (G2) had not significantly different in fresh and dry leaf weight. Meanwhile, the plant genotype did not affect other growth characteristics such as plant height, the number of leaves, and the length and width of the leaflets, and overall, the characters were similar between the observed genotypes.

Saltwater intrusion ecophysiological effects on Pseudophoenix sargentii, Roystonea regia, Sabal palmetto “Lisa,” and Thrinax radiata in South Florida

Climate change will alter natural areas on a global scale within the next century, especially in low-lying coastal areas where sea-level rise is predicted to severely degrade or destroy many ecosystems. As sea-level rise continues, it is expected that salinity due to saltwater intrusion will impact soil health and agricultural production, this is of even greater importance in areas such as South Florida where the surface and groundwater resources are hydrologically connected due to the shallow and highly permeable limestone soils. The chlorophyll concentrations in leaf tissue were chosen as the primary health indicator to assess whether this is a valuable factor to consider for plant health risk assessment and whether optical sensor technology such as the SPAD and NDVI, are valuable tools when understanding the impact seawater encroachment has on plant nitrogen uptake. Therefore, the aim of this study was to evaluate the effects of salt concentrations on plant growth and health of four palm species. The treatments were from pure reverse osmosis water, Fresh water, brackish water, seawater and hypersaline water (0, 0.5, 5, 10, 15, 25, and 50 ppt). Control treatment that received reverse osmosis filtrated water with a salinity concentration of 0 ppt had the highest health-indicator averages compared to treatment 50 ppt. As the salinity increased, all health indicators gradually declined or remained rather constant and declined as they approached the greater salinity concentrations. The growth parameters and chlorophyll content were reduced over time, particularly at higher salt concentrations for all palm species studied. The chlorophyll content by SPAD and the normalized difference vegetation index (NDVI) can be used as health indicators of the palm species studied, as it was observed in this study a decline in the chlorophyll content as there was an increase in salt concentrations. It is important to emphasize that leaf chlorosis and subsequent decline of palm species were observed in the treatment with higher salt concentration, thus highlighting the importance of chlorophyll content as an indicator of plant health. The species Roystonea regia was very susceptible to salinity, and the palm Sabal palmetto is more susceptible to salinity than the Thrinax radiata and Pseudophoenix sargentii palms.

Leaf age and light stress affect the ability to diagnose P status in field grown potatoes.

Phosphorus (P) deficiency is a global issue which can severely impact the yield of crops, including the P demanding and important food crop potato. Diagnosis of P status directly in the field can be used to adapt P fertilization strategies to the needs of the evolving crop during the growing season and is often estimated by analyzing P concentrations in leaf tissue. In this study, we investigate how diagnosis of P status in field grown potato plants is affected by leaf position and time of measurement in a randomized block experiment. The concentrations of many essential plant nutrients are highly dynamic, and large differences in nutrient concentrations were found in potato leaves depending on leaf age and time of sampling. During tuber initiation, P concentrations decreased in a steep gradient from the youngest leaves (0.8%) towards the oldest leaves (0.2%). The P concentrations in the youngest fully expanded leaf decreased by 25-33% within just 7 days, due to a high remobilization of P from source to sink tissue during crop development. 40 days later P concentrations in all leaves were near or below the established critical P concentration of 0.22%. The P concentration in leaf tissue thus depends on sampling time and leaf position on the plant, which in a practical setting might prevent a meaningful interpretation in terms of fertilizer recommendation. The chlorophyll a fluorescence parameter "P-predict", derived from the fluorescence transients, is an alternative to the classical chemical analysis of nutrient concentrations in leaf tissue. P-predict values serve as a proxy for the bioavailable P pool in the leaf and can be measured directly in the field using handheld technology. However, in conditions of high solar irradiation, the P-predict values of the most light-exposed leaf positions, i.e. the younger leaves, were found to be severely impacted by photoinhibition, preventing accurate characterization of the P status in potatoes. Shading the plants can reverse or prevent photoinhibition and restore the diagnostic capabilities of the P-predict approach.

Physiological and Biochemical Responses of Apple (Malus domestica Borkh.) to Biostimulants Application and Substrate Additives under Salinity Stress

The issue of high concentration of salt in soil is not restricted to coastal areas, but also expands to cultivated lands, complicating, or even intercepting, the growth of plants. The objective of this paper is to study the effect of zeolite, compost and effective microorganisms (EM), seaweed extract, and ceramic powder on MM106 apple (Malus domestica Borkh.) plants in normal and saline conditions. More specifically, the weight of the dry matter of the plants, physiological parameters, proline, carbohydrate, carotenoid, phenolic, and flavonoid concentrations in leaf tissues and antioxidant capacity were determined. At the end of the experiment, it was ascertained that the plants of the treatments which included zeolite or EM exhibited the highest dry matter weight of the leaves in normal (5.07 g and 4.68 g, respectively) and saline conditions (4.14 g and 3.02 g, respectively), while the leaf dry weight in the control treatment was 4.37 g in the absence and 2.34 g in the presence of NaCl. Furthermore, these treatments resulted in significantly higher proline concentration in plant leaves under salinity with values of 5.63 in the EM treatment, 2.44 in the zeolite treatment, and 0.75 μmol/g of leaf fresh weight in the control. At the same time, the application of ceramic powder in combination with effective microorganisms led to the highest rate of photosynthesis in salinity conditions (12.8 μmol CO2/m2s), while the seaweed extract spraying was associated with low stomatal conductance in all treatments (0.09–0.13 mol H2O/m2s). Overall, the application of effective microorganisms appeared to associate more with plant vigor in both normal and salinity conditions. In this context, the implementation of EM could improve the growth of potted plants, but it could also be used in orchards before and after their establishment.

Impacts of Elevated Ozone and Ozone Protectants on Plant Growth, Nutrients, Biochemical and Yield Properties of Turnip (Brassica Rapa L.)

ABSTRACT An experiment was conducted at Woodhouse farm, Horticultural Research Station, Ooty, during October 2017 to March 2018 to quantify the impact of elevated ozone and ozone protectant spray on plant growth, nutrients, biochemical and yield properties of turnip crop. The experiment was laid out in a factorial completely randomized block design and was replicated thrice. Elevated ozone exposure on turnip significantly reduced the plant height, tuber size, tuber weight, chlorophyll ‘a,’ chlorophyll ‘b’ and total chlorophyll content as well as the nutrient content of plant, viz., total nitrogen, total potassium, total manganese, iron, zinc and copper, also affected. Elevated ozone exposure significantly increased the antioxidant enzyme activity like catalase and peroxidase activity in addition to increment in total phosphorus content in leaf tissues. However, ozone protectants played a major role in nullifying the tropospheric ozone effect on growth and development, physiological traits and yield of turnip while tested with panchagavya performed better followed by neem oil and ascorbic acid.

New Insight into Short Time Exogenous Formaldehyde Application Mediated Changes in Chlorophytum comosum L. (Spider Plant) Cellular Metabolism.

Chlorophytum comosum L. plants are known to effectively absorb air pollutants, including formaldehyde (HCHO). Since the metabolic and defense responses of C. comosum to HCHO are poorly understood, in the present study, biochemical changes in C. comosum leaves induced by 48 h exposure to exogenous HCHO, applied as 20 mg m-3, were analyzed. The observed changes showed that HCHO treatment caused no visible harmful effects on C. comosum leaves and seemed to be effectively metabolized by this plant. HCHO application caused no changes in total chlorophyll (Chl) and Chl a content, increased Chl a/b ratio, and decreased Chl b and carotenoid content. HCHO treatment affected sugar metabolism, towards the utilization of sucrose and synthesis or accumulation of glucose, and decreased activities of aspartate and alanine aminotransferases, suggesting that these enzymes do not play any pivotal role in amino acid transformations during HCHO assimilation. The total phenolic content in leaf tissues did not change in comparison to the untreated plants. The obtained results suggest that HCHO affects nitrogen and carbohydrate metabolism, effectively influencing photosynthesis, shortly after plant exposure to this volatile compound. It may be suggested that the observed changes are related to early HCHO stress symptoms or an early step of the adaptation of cells to HCHO treatment. The presented results confirm for the first time the direct influence of short time HCHO exposure on the studied parameters in the C. comosum plant leaf tissues.

Relative Growth of Lettuce (Lactuca sativa) and Common Carp (Cyprinus carpio) in Aquaponics with Different Types of Fish Food

Aquaponics has the potential to contribute to food security in urban Nepal, where agricultural land near cities is rapidly being converted for other uses. This technology’s use is expanding in Nepal, but the relatively high cost of commercial fish food is a hindrance. As a result, some aquaponics operators are resorting to alternative, less expensive fish foods. Since the primary input of nutrients to the plants grown in aquaponics comes from the fish food, an evaluation of the impact of fish foods on plant and fish growth is needed to help operators evaluate the costs and benefits of commercial compared to alternative fish diets. This study evaluated the growth of lettuce and common carp, the most common species of plant and fish used in aquaponics in Nepal, with three fish diets (commercial fish food, commercial chicken food, and a homemade diet with mustard oil cake and rice bran) at a commercial aquaponics farm with nine identical systems allowing for three replicates of the three fish food treatments. There were no significant differences in the measurements of lettuce growth (stem length, root length, and stem mass) and few differences in nutrient concentrations in leaf tissue. The specific growth rate of the carp fingerlings was lowest for the fish in the systems fed with the homemade diet (0.21) compared to those fed commercial fish food or commercial chicken food (0.31 and 0.28, respectively). These findings suggest that aquaponics operators who have been buying the more expensive commercial fish food with fish meal as its protein source can save 50–95% of the related costs by using commercial chicken food or the homemade diet defined in this study. This could potentially encourage the expansion of aquaponics systems in Nepal.