Decrease In Total Chlorophyll Content Research Articles

Response of Grafted Olive (Olea europaea L. Cv. Coratina) to Water Deficit Conditions

Drought is one of the most damaging abiotic stresses; water deficit problem is increasingly occurring due to global climate change and negatively affects crop growth and productivity. Grafting on tolerate rootstocks is a promise approach to mitigate negative impacts of drought stress and ensure production sustainability. The present study was carried out to investigate the effect of water deficit stress on Coratina olive plants grafted on the following cultivars as rootstocks (Coratina, Koroneiki, Manzanillo, Picual and Sorani). Three water levels based on soil field capacity (FC) (100, 50% and 25% of FC) were used for water deficit treatments. Water deficit decreased shoot growth, stem diameter, leaves number and area, shoot and root weight. Leaf analysis showed marked decrease in total chlorophyll content while proline, total sugars and phenolic content increased with increasing water deficit level. The studied grafting combination differed in their response to water deficit treatments; Coratina grafted on Sorani and Koroneiki recorded higher values of growth parameters and accumulated higher amount of osmolytes (proline and total sugars) and phenolic compared to other grafted olive plants.

Stress-related physiological responses and ultrastructural changes in Hypoxis hemerocallidea leaves exposed to cadmium and aluminium

Hypoxis hemerocallidea is a medicinal plant containing hypoxoside (a pharmacologically active phytosterol diglucoside). This study evaluated the elemental composition in leaves of H. hemerocallidea treated with cadmium (Cd) and aluminium (Al) using scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDX). The impact of Cd and Al on photosynthetic pigments and performance, antioxidant activities and ultrastructure were also assessed. Corms of H. hemerocallidea were micropropagated, rooted and then exposed to varying concentrations of Cd, Al, and Cd + Al for six weeks. The SEM/EDX analysis indicated a two-fold increase in carbon content across all treated plants compared to the control. No/little Cd was detected in the leaves compared to a progressive increase in Al concentration with increasing Al treatment levels. This indicted that Al is more readily translocated to the shoots compared to Cd. Plants treated with Cd exhibited a significant decrease in total chlorophyll content accompanied by reduced photosynthetic performance and lower relative electron transport rates. Cd and Al exposure led to higher carotenoid, superoxide dismutase and malondialdehyde levels, indicating oxidative stress. Cd-treated plants displayed increased amylase activity and decreased carbohydrates content. Ultrastructural alterations occurred with exposure to Cd and Al, including abnormal swelling or disintegration of chloroplasts and thylakoid degeneration. An increase in starch grains and a decrease in plastoglobuli were also noted. In conclusion, this investigation provides evidence that both Cd and higher concentrations of Al exert detrimental effects on the ultrastructure, metabolism and photosynthetic performance of H. hemerocallidea, contributing to reduced growth and biological activity when stressed.

Influence of Drought Stress and Foliar Application of Salicylic Acid on Early Vegetative Stage of Cacao

Cacao (Theobroma cacao L.) is noted to have a low tolerance to drought and is, therefore, not resilient to prolonged dry periods. The study sought to evaluate the morpho-anatomical and physiological responses of two clonal seedlings of cacao BR25 and K9 under drought stress and to explore the potential alleviating effects of salicylic acid (SA) at concentrations of 0.5 and 1.0 mM on the early vegetative stage. Eleven-month-old BR25 and K9 cacao were pre-treated with foliar application of 0.5 and 1.0-mM SA for 2 wk before the onset of drought conditions. Well-watered and drought seedlings with no pre-treatments served as the control. Water was withheld for 20 d, after which rewatering resumed for 3 mo. Results revealed that after 20 d of drought, both clonal varieties experienced a significant decline in relative water content (RWC) and increased ascorbate peroxidase (APX) and catalase activity. Changes in stem diameter were observed after a rewatering period of 3 mo. K9 exhibited a noticeable reduction in root and shoot dry weight and stomatal aperture after 20 d of drought, whereas BR25 showed a decrease in total chlorophyll content and chlorophylls a and b. Furthermore, the results of the study suggest that 0.5-mM SA has the potential to mitigate the drastic effects during drought in BR25 and K9 cacao by improving RWC, stomatal length, and width. On the other hand, 1.0- mM SA has the potential to alleviate the effects of drought experienced earlier on by improving root dry weight and APX activities of the seedlings.

Salt stress influences the proliferation of Fusarium solani and enhances the severity of wilt disease in potato

Soil salinity has emerged as a critical abiotic stress in potato production, whereas wilt disease, caused by Fusarium solani, is the significant biotic stress. An experiment was performed to decipher the occurrence of wilt incidence by F. solani FJ1 under the influence of salinity in both in vitroand pot culture conditions. High salt concentration negatively influenced root and shoot development in the variety “Kufri Jyoti” but positively affected the mycelial growth and sporulation behaviours of F. solani FJ1. There was abundant whitish mycelial growth with enhanced biomass and high sporulation (microconidia production) in F. solani FJ1 cultured on salt-supplemented media. Moreover, under high salinity conditions (EC 2–8 dS m−1), severe wilting and rotting of vascular bundles were observed in plants artificially inoculated with F. solani FJ1. The mortality rate of potato plants was significantly higher under individual and combined stresses as compared to control. The wilt index of individual and combined stressed plants was also substantially higher compared to the control. Additionally, compared to the control, there was a significant decrease in total chlorophyll content and membrane stability index of the leaves under combined stress. However, the total phenols were increased under stress conditions. The total sugar content of potato plants decreased in infected plants, but increased when exposed to salt stress or a combination of salt stress and pathogen infection. F. solani infection also increased the activity of peroxidase (POX) and decreased the activity of phenylalanine ammonia-lyase (PAL) and catalase (CAT). These results suggest that Fusarium wilt and dry rot will be a more severe disease for potato cultivation in saline soils.

Comparative Transcriptomics and Metabolomics Analyses of Avicennia marina and Kandelia obovata under Chilling Stress during Seedling Stage

One of the most productive ecosystems in the world, mangroves are susceptible to cold stress. However, there is currently insufficient knowledge of the adaptation mechanisms of mangrove plants in response to chilling stress. This study conducted a comparative analysis of transcriptomics and metabolomics to investigate the adaptive responses of Kandelia obovata (chilling-tolerant) and Avicennia marina (chilling-sensitive) to 5 °C. The transcriptomics results revealed that differentially expressed genes (DEGs) were mostly enriched in signal transduction, photosynthesis-related pathways, and phenylpropanoid biosynthesis. The expression pattern of genes involved in photosynthesis-related pathways in A. marina presented a downregulation of most DEGs, which correlated with the decrease in total chlorophyll content. In the susceptible A. marina, all DEGs encoding mitogen-activated protein kinase were upregulated. Phenylpropanoid-related genes were observed to be highly induced in K. obovata. Additionally, several metabolites, such as 4-aminobutyric acid, exhibited higher levels in K. obovata than in A. marina, suggesting that chilling-tolerant varieties regulated more metabolites in response to chilling. The investigation defined the inherent distinctions between K. obovata and A. marina in terms of signal transduction gene expression, as well as phenylpropanoid and flavonoid biosynthesis, during exposure to low temperatures.

Impact of Excess Magnesium Salt Supply on Rice Yield, Physiological Response, and Grain Mineral Content

Magnesium nutrition in plants has remained largely unexplored compared to other essential elements. Although the impact of magnesium deficiency on plants has been reported from numerous studies, the responses of plants to excess magnesium salt levels have received less attention. Using five different magnesium levels (0, 500, 1000, 1500, and 2000 ppm) and two magnesium sources (MgSO4 and MgCl2), this study evaluated the effect of excess magnesium salts on rice production and associated physiological processes on a hybrid rice cultivar ‘XP 753’. Rice morphological and physiological parameters, including plant growth, biomass, root morphological features, tissue and grain mineral concentrations, membrane injury (MI), chlorophyll, malondialdehyde (MDA) concentrations, proline concentrations, as well as gas exchange parameters, were evaluated. A dose-dependent reduction in above- and below-ground shoot and root morphological features was observed under the application of magnesium salts on the soil substrate. Analysis of physiological parameters demonstrated that an inhibition in plant growth, biomass, and yield was due to the decrease in total chlorophyll content, net photosynthesis rate, and membrane stability in rice. Furthermore, this study showed that the application of magnesium salts to soil interfered with the uptake and translocation of minerals and significantly increased reactive oxygen species (ROS), malondialdehyde (MDA), and proline levels, indicating the toxic effects of excess magnesium salts on rice plants.

Exogenous N-hexanoyl-l-homoserine lactone mitigates acid rain stress effects through modulation of structural and functional changes in Triticum aestivum leaf

Acid rain (AR) is a global environmental problem that causes a number of morphological, physiological and molecular changes in plants. N-acyl homoserine lactones, as bacterial quorum sensing signal molecules, mediate a number of physiological processes in plants. In this study, we have demonstrated for the first time the stress-protective role of AHL foliar treatment under conditions of abiotic stress - acid rain. The effects of simulated acid rain (SAR), treatment of plants with N-hexanoyl-l-homoserine lactone (C6-HSL) solution, and a combination of these two factors on the microstructure of the leaf surface, photosynthetic pigments, secondary metabolites, and lipoxygenase activity in winter wheat plants were analyzed. It was established that on the fourth day following treatment of 14-day-old plants with C6-HSL, the thickness of the outer cell wall of the leaf epidermis, together with the cuticle layer, increased by 15 %. SAR treatment resulted in a significant thinning of the cell wall (33 %), while pretreatment with C6-HSL followed by SAR reduced cell wall thickness by only 9 %. Under SAR, the cuticular wax layer was destroyed and there were unequal wax lamellae on the epidermal surface, while in C6-HSL treated plants only partial cracking of the cuticular wax layer, slight destruction of the wax lamellae, and formation of wax crusts took place. C6-HSL induced a significant increase in total chlorophyll content under non-SAR conditions, and significantly mitigated the decrease of total chlorophyll content caused by SAR. Lipoxygenase activity, the content of total phenols, flavonoids, and proline increased after treatment of plants with C6-HSL solution alone and in combination with SAR. This is the first report on the possibility of using C6-HSL as an ecological biostimulator under conditions of AR.

Stabilitas Ekstrak Pewarna Daun Singkong (Manihot esculenta C.) Pada Perlakuan pH Awal dan Suhu Penyimpanan

Cassava leaves are leaves that can be used as a source of natural dye. Cassava leaves have a fairly high chlorophyll content and can be extracted into green dye extract. This study aimed to determine how the stability of the cassava leaf dye extract at the initial pH treatment and storage temperature and to determine the initial pH and temperature that provide the best stability to the cassava leaf dye extract during storage. This experiment used a completely randomized design with two factors. The first factor is the initial pH which consists of pH 9, pH 10 and pH 11. The second factor is the storage temperature consisting of cold temperature (8±2ºC) and room temperature (28±2ºC). The data were analyzed by analysis of variance to determine the effect of treatment on the observed variables. The results showed the initial pH and temperature treatment during storage and their interactions affected the total chlorophyll content, chlorophyll a content, chlorophyll b content, antioxidant capacity, brightness level value (L*), redness level value (a*) and yellowness level value ( b*) cassava leaf coloring extract. Cassava leaf dye extract was most stable at initial pH 9 and cold temperature (8±2ºC) during storage. Storage of cassava leaf dye extract for 7 days caused a decrease in total chlorophyll content of 48.44%, chlorophyll a by 46.86%, chlorophyll b by 49.35%, antioxidant capacity by 30.87%, redness level value (a*) by 62.91%, but caused an increase in the value of the redness level (a*) of 62.91%, the value of the brightness level (L*) of 29.28% and the value of the yellowness level (b*) of 49.02% against the control.

Constant and Intermittent Contact with the Volatile Organic Compounds of Serendipita indica Alleviate Salt Stress In Vitro Ocimum basilicum L.

Serendipita indica is a plant growth-promoting fungus. It is a natural soil dweller that can colonize the roots of a wide range of plants, including cultivated crops. S. indica has been reported to improve plant nutrient uptake and increase stress tolerance when inoculated into the soil. The present study was undertaken to study the effect of volatile organic compounds (VOCs) of S. indica on salt-stressed Ocimum basilicum ‘Fin vert’ in vitro, either in a culture vessel with a semi-solid medium or via a modified temporary immersion bioreactor system (SETIS). For all salt concentrations, VOCs of S. indica significantly improved plant growth in both semi-solid medium and SETIS bioreactors. This resulted in heavier and taller plants, more shoots per plant, and longer roots. This was even observed for the control without salt. At 9 g/L NaCl, plants with Serendipita were able to give longer roots than those without (1.2 cm vs. 0.0 and 1.7 cm vs. 1.7 cm) in the semi-solid medium and SETIS, respectively. Nevertheless, the VOCs were not able to make the plant salt tolerant to this high concentration. The increase in total phenolic and flavonoid content and radical scavenging suggest that the antioxidant defense system is triggered by the S. indica VOCs. In the semi-solid system, without VOCs, 1 g/L NaCl led to an increase in total chlorophyll content (TCC) and a significant decrease in TCC was further measured only at 6 g/L NaCl or more. However, when VOCs were added, the bleaching effect of the salt was partially restored, even at 6 and 9 g/L NaCl. A significant decrease in TCC was also measured in the SETIS system at 6 g/L NaCl or more and treatment with VOC did not make any difference. An exception was 9 g/L, where the VOC-treated plants produced more than three times more chlorophyll than the non-treated plants. These findings will encourage the application of Serendipita indica for stress reduction. In addition, the proposed original adaptation of a temporary immersion system will be instrumental to investigate stress reduction associated with volatile compounds and better understand their mechanism of action.

Phytotoxicity of Tetracycline and Amoxicillin on Vigna radiata and its Remediation Potential in Hydroponic System

The current study aimed to evaluate the phytotoxicity of tetracycline and amoxicillin on Vigna radiata and its remediation potential in hydroponic system. Germinated seeds of Vig-na radiata were planted with varying concentra-tions of tetracycline and amoxicillin (150 – 500 mg L−1) in triplicates (n=3) for three weeks. Tox-icity biomarkers, i.e. changes in plant biomass, photosynthetic pigment, phenol, flavonoid con-tent and antioxidative enzymes were estimated after completion of 3 weeks. The results illus-trated that high tetracycline concentration (500 mg L-1) in hoagland media resulted decrease in total chlorophyll content (3.045- 2.252 mg total chlorophyll /g tissue) while in case of amoxicillin, chlorophyll content was increased (5.18 - 7.309 mg total chlorophyll /g tissue). Carotenoid, Total flavonoid and phenolic content, were also sig-nificantly (p < 0.05) reduced due to toxicity of these antibiotics. Antioxidant enzyme like cata-lase showed 7.22 % degradation in their activity with highest concentration (500 mg kg-1) of tet-racycline and 27.3 % degradation was found in case of amoxicillin. Glutathione peroxidase ac-tivity was also decreased in both of the cases. Subsequently, the Vigna radiata showed 63% remediation potential with tetracycline and 93 % in case of amoxicillin. Hence, overall results indicate that, the phytoremediation rate shown by Vigna radiata is very promising and these antibiotics also showed its toxicological impact on plants.

Electrically assisted ionic gelling encapsulation of enzymatically extracted zinc‐chlorophyll derivatives from stinging nettle (Urtica urens L.)

AbstractThis study evaluates the effect of four different encapsulation techniques. Zn‐chlorophyll derivatives obtained by enzymatic extraction with 26.80% yield compared to nonenzymatic extraction from stinging nettle were encapsulated with (i) ionic gelling, (ii) ionic gelling + chitosan coating, (iii) electrically assisted ionic gelling (iv) electrically assisted ionic gelling + chitosan coating methods. The decrease in total chlorophyll content at the end of the 8 weeks storage in the capsules according to the initial amount was found to be 17.32, 44.97, 4.18 and 26.52%, respectively. Depending on the total chlorophyll content, the decrease in a* value in the capsules according to the initial amount was found to be 30.00, 68.63, 8.16 and 53.04%, respectively. The capsules prepared by the electrical method provided the highest protection of chlorophyll during storage. Chitosan application as a second layer to capsules resulted in an increase in chlorophyll decay in both ionic gelling and electrically assisted ionic gelling methods (p &lt; 0.05). It has been determined that the application of chitosan in chlorophyll encapsulation is not appropriate due to the poor color and malodor effect.Practical applicationsNatural colorants are food additives that are widely used to increase the acceptance of products in the food industry. Nowadays, the demand of consumers for natural products has increased the studies on this subject and the search for solutions to problems. The most important problem of natural colorants is their low stability. The development of natural colorants with high stability requires different techniques such as encapsulation or innovations in the molecular structure. With the applied techniques, the stability of natural products can be increased as well as innovative forms of the products obtained can find market share in the industry.

Insights into role of STP13 in sugar driven signaling that leads to decrease in photosynthesis in dicot legume crop model (Phaseolus vulgaris L.) under Fe and Zn stress.

Mineral (Fe/Zn) stress significantly affects fundamental metabolic and physiological responses in plants that results in reduction of plant growth and development. Deficiency of these micronutrients leads to inhibition of photosynthesis by having impact on various crucial biological processes like protein synthesis, primary and secondary metabolism and carbohydrate partitioning between source and sink tissues. In the present study, common bean variety Shalimar French Bean-1 (SFB-1) plants were used as an experimental material and were grown under in vitro condition on four different MGRL media i.e. normal MGRL medium (Control), MGRL without Fe (0-Fe), MGRL without Zinc (0-Zn) and MGRL with excess Zn (300-Zn) for 21days under optimum conditions. Shoot and root tissues from all the treatments were harvested and further subjected to estimation of total chlorophyll, total sugar and extraction of total RNA for differential gene expression of sugar transporter 13 (STP13). We observed significant decrease in total chlorophyll content in samples harvested from mineral stress plants. However, the concentration of total sugar and fold expression of STP13 gene was significantly higher in shoots of Fe/Zn stressed and in roots of 300-Zn plants. We observed higher accumulation of sugar under stress condition that correlated with high expression of sugar transporter 13 (STP 13). Further, we observed decrease in the chlorophyll content under stress conditions. Based on these findings, we propose the role of sugar driven signaling in decreasing photosynthesis in case of common bean. The decrease in photosynthesis is confirmed by observing significant decrease in chlorophyll content in stressed plants.

CaGnT-III, an N-acetylglucosaminyltransferase gene from pepper, positively regulates plants tolerance to abiotic stresses by enhancing antioxidant ability

As a common post-translational modification pathway, glycosylation plays important roles in maintaining proteins’ inherent conformations and normal functions. The contribution of core N-glycans formed in endoplasmic reticulum (ER) to plant tolerance against salt stress has been well-studied; however, the knowledge about the involvement of complex N-glycans synthesized in Golgi apparatus is limited. Here, we report that a pepper N-acetylglucosaminyl-transferase III gene CaGnT-III, which takes part in the maturation of complex N-glycans, can respond to heat, salt, and drought stress. Furthermore, silencing of CaGnT-III compromises pepper tolerance and its overexpression enhances Arabidopsis tolerance, to the above abiotic stresses. Under stressed conditions, compared to those in the control with empty vector, in CaGnT-III silenced pepper seedlings, the increase of MDA (malondialdehyde) accumulation and the decrease of total chlorophyll content were aggravated, while the enhancement of proline content, CAT (catalase) and APX (ascorbate peroxidase) activities, and stress-related genes expression were weakened. On the contrary, overexpression of CaGnT-III in Arabidopsis presented the opposite results. Therefore, we speculate that CaGnT-III gene positively regulates the formation of plants tolerance to abiotic stress by enhancing antioxidant ability.

Effect of Arsenic Toxicity on Chlorophyll Content and Antioxidative Enzymes Activities in Rice Seedlings

Aims: Arsenic (As) contamination in rice is at alarming level as majority of rice growing regions in India are As contaminated. Present investigation is designed to study the better understanding of the physiological and biochemical mechanisms in the amount of chlorophyll change and antioxidative enzymes activity under arsenic stress on rice variety IET-4786 (Shatabdi).&#x0D; Study Design: Completely Randomized Design.&#x0D; Place and Duration of Study: The experiment was carried out in the departmental laboratory of Plant Physiology, Bidhan Chandra Krishi Viswavidyalaya (BCKV), Mohanpur, Nadia,West Bengal during the year 2017-18.&#x0D; Methodology: Two classes of inorganic arsenic- As(V) in the form of Sodium arsenate (Na2HAsO4.7H2O, M. W. = 321.01) and As(III) in the form of Sodium arsenite (NaAsO2, M.W. =129.91) were added to the modified Hoagland nutrient solution@ 2.5, 5.0, 7.5, 10.0, 12.5,15.0 mg L-1concentration. After 20 days of treatment, rice seedlings under arsenate/arsenite treatments were analyzed for change in total chlorophyll content and antioxidative enzymes activity such as superoxide dismutase (SOD: EC 1.15.1.1), catalase (CAT: EC 1.11.1.6), ascorbate peroxidase (APX: EC1.11.1.11) and peroxidase (POD: EC 1.11.1.7).&#x0D; Results: A noticeable decrease in total chlorophyll content was observed with arsenic treatments as compared to control. Various antioxidative enzymes showed significant variable response upon exposure to As(III) and As(V). SOD activities increased at low arsenic exposure up to 7.5 mg L-1 but decreased with further increase in arsenic treatments. APX and POD activities were increased with increase in arsenic concentrations while CAT activity displayed decreasing trend.&#x0D; Conclusion: The results are suggestive of differential metabolism of As(III) and As(V) in rice and could exert harmfulness in the early development stage of rice at inappropriate concentrations.

Performance of Hylocereus (Cactaceae) species and interspecific hybrids under high-temperature stress

High temperatures limit the successful cultivation of the Hylocereus species on a global basis. We aimed to investigate the degree of heat tolerance in three species, namely, the diploids Hylocereus undatus and H. monacanthus, and the tetraploid H. megalanthus, and nine of their interspecific-interploid hybrids. Rooted cuttings were exposed to heat stress (45/35 °C) or control conditions (25/20 °C) for eight days. Initially, the plants were screened for their tolerance to heat stress and ranked into four heat tolerance categories: good tolerance, moderate tolerance, low tolerance, or sensitive, according to the decrease in the maximum quantum efficiency of photosystem II (Fv/Fm) and visual stem damage. The physiological and biochemical performances of the parental species and of three hybrids representing three different heat-tolerance categories were further analyzed in depth. H. megalanthus (classified as heat sensitive) showed a 65% decrease in Fv/Fm and severe visual stem damage, along with a marked reduction in total chlorophyll content, a large increase in malondialdehyde, and inhibition of catalase activity. H. undatus and H. monacanthus, (classified as low-tolerance species) exhibited slight stem “liquification.” The good-tolerance hybrid Z-16 exhibited the best performance under heat stress (21% decrease in Fv/Fm) and the absence of stem damage, coupled with a small decrease in total chlorophyll content, a slight increase in malondialdehyde, high antioxidant activity, and proline accumulation progressing with time. Our findings revealed that most of the hybrids performed better than their parental species, indicating that our breeding programs can provide Hylocereus cultivars suitable for cultivation in heat-challenging regions.

Cadmium toxicity in African yam bean (Sphenostylis stenocarpa (HOCHST. EX A.RICH.) HARMS genotypes

The aim of the study was to investigate the growth responses of African yam bean (Sphenostylis sternocarpa (Hochst. ex A. Rich.) Harms (AYB) to cadmium pollution. Top garden soil (0 – 10 cm) was obtained as pooled and polluted with cadmium (as CdCl2) at the rate of 12 mg kg-1, which is equivalent to 3 times the ecotoxicological screening value of Cd. The polluted soils were made ready for use 3 days later. Nine selected AYB accessions (TSs-87, TSs-89, TSs-90, TSs-91, TSs-92, TSs-93, TSs-94, TSs-95, and TSs-96) were pre-soaked for 30 minutes and then sown in the polluted and unpolluted soils. Data collected were subjected to ANOVA, and means were separated at 95 % confidence interval. Results showed that incidence of cadmium pollution significantly delayed seedling emergence in all tested AYB accessions by at least one day (p &lt; 0.05). Despite exposure to Cd, TSs-96 attained 50 % emergence faster than other accessions. Although there were general reductions in yield due to exposure to Cd, TSs-92 showed the least percentage yield reduction (50 %), compared to 74 % yield reduction in TSs-93, thereby suggesting a comparatively better yield capacity compared to the other test accessions. Overall, decrease in total chlorophyll content seems to be the major reason of injury in Cd-exposed plants.

INTERAKSI ANTARA EKSTRAK AIR BAWANG MERAH (Allium cepa L) DENGAN AIR KELAPA (Cocos nucifera) DALAM MENUNDA SENESCENE POLONG KACANG KAPRI (Pisum sativum L.)

This study aims to determine whether a mixture of red onion water extract and coconut water can delay senescence of pea bean pods. The research was conducted in Botanical Laboratory, Department of Biology, Faculty of Mathematics and Natural Sciences, University of Lampung in October 2017. The research was arranged in 3x3 factorial design. Factor A is coconut water with concentration 0% v / v, 25% v / v, 50% v / v. Factor B is an onion water extract with a concentration of 0% v / v, 12.5% v / v, 25% v / v. The variables in this research are fresh weight, dry weight, relative water content, total chlorophyll content of peas pods. The quantitative parameters in this study were all the mean (μ) variable. Homogeneity variation was determined by Levene test at 5% real level. Tukey's variety and assay analysis was performed at a real 5% level. The results showed that onion water extract, coconut water, and its interaction had no significant effect on the fresh weight of beans, but the interaction between onion and coconut water extracts had a significant effect on fresh weight. Likewise, the treatment of water extract of onion and coconut water did not significantly affect the relative water content of the peanut pod, but the interaction both had a real effect on both. From the results of the study it was concluded that the addition of red onion water extract can not increase the ability of coconut water in delaying the process of senescence of pea pods indicated by the decrease of total chlorophyll content and dry weight.

Ecophysiological and phytochemical responses of Salvia sinaloensis Fern. to drought stress

Salvia sinaloensis Fern. (sage) is a medicinal plant containing plant secondary metabolites (PSMs) with antioxidant properties. The current study investigated the effects of drought stress on S. sinaloensis morphological and ecophysiological traits, and active constituent production. Sage plants were cultivated in controlled conditions for 34 days and exposed to full irrigation as control, half irrigation, or no irrigation. Changes in growth index (G.I.), dry biomass, leaf water potential (LWP), physiological parameters, active compounds, volatilome (BVOCs) and essential oils (EOs) were determined. Not irrigated plants showed a decrease in total chlorophyll content (~ − 14.7%) and growth (G.I., ~ − 59.4%) from day 18, and dry biomass at day 21 (− 56%), when the complete leaf withering occurred (LWP, − 1.10 MPa). Moderate drought stressed plants showed similar trends for chlorophyll content and growth but kept a constant LWP (− 0.35 MPa) and dry biomass throughout the experiment, as control plants. Carotenoids were not affected by water regimes. The photosynthetic apparatus tolerated mild to severe water deficits, without a complete stomatal closure. Plants under both stress conditions increased the percentage of phenols and flavonoids and showed altered BVOC and EO chemical profiles. Interestingly Camphor, the main EO oxygenated monoterpene, increased in moderate stressed plants while the sesquiterpene hydrocarbon Germacrene D decreased. The same trend was seen in the headspace under stress severity. The data evidenced a possible role of the active molecules in the response of S. sinaloensis plants to drought stress. Taking together, these findings point at S. sinaloensis as a potential drought adaptive species, which could be used in breeding strategies to obtain sages with high quality PSMs, saving irrigation water.

VARIATIONS OF PROXIMAL COMPOSITION IN PILEA MICROPHYLLA (L.) LIEBM DUE TO DESICCATION AND REHYDRATION IMPACTS

Water deficiency is the most significant abiotic stress factor for land plants. Most plants are unable to survive desiccation to the air dry state. There are however a few species from lower plant groups to flowering plants that tolerate desiccation known as resurrection plants. So, the present investigation was undertaken tostudy the biochemical changes in Pileamicrophylla against desiccation (1, 3, 5 and 7 days) and rehydration (30 min) stress. As an initial part of the study total sugar, protein and proline content were analyzed and showed a gradual decline during the stress periods. The SDS-PAGE analysis of protein indicated thedisapperance of certain bands in the desiccated and rehydrated samples (7D) when compared to the control indicating the denaturation of proteins during stress. Similarly, the appearance of new bands (15kDa on 3D and 20 and 17kDa on the 5D) were noticed suggesting the formation of stress related proteins to tide over desiccation. The amount of free amino acids increased in P. microphylla, in pace with desiccation periods. Constitutive increase in the level of proline (the stress amino acid) accumulation is seen when compared with the control i.e., 6 fold higher than that of the control, after exposed to desiccation for 5 D. Increase in proline level relating to exposure time of desiccation stress suggests its role as osmolyte. Similarly, a reduction in chlorophyll level and an increase in carotenoid were also observed during stress. Decrease of total chlorophyll content was observed with duration of desiccation. The decrease in chlorophyll a and b was recovered during rehydration up to 5 D. Further studies are warranted at molecular level in terms of stress proteins and genes involved in desiccation tolerance in this plant.

Effects of NaHCO&lt;sub&gt;3&lt;/sub&gt; Stress on the Growth and Physiological Indexes of Pumpkin Seedlings

Few studies have investigated the alkali-based salt resistance aspect of plants. Here, we used 2 pumpkin cultivars ('Cucurbita ficifolia Bouch.' and 'Chuandilong') to study the growth and physiological response mechanisms of pumpkin to different levels of NaHCO3 stress. After second true leaf development, pumpkin seedlings were treated with varying levels of NaHCO 3 stress (0, 30, 60 and 90 mmol/L) during sand culture. The chlorophyll content, electrolyte leakage, malondialdehyde (MDA) contents, proline contents, soluble sugar contents and superoxide dismutase (SOD) and peroxidase (POD) activities of both cultivars were investigated. Finally, the growth and physiological indexes of pumpkin seedlings under NaHCO3 stress were explored. The results showed that the chlorophyll a, chlorophyll b and total chlorophyll of both pumpkin seedlings increased with exposure to low NaHCO3 concentrations (0-30 mmol/L) and then decreased with exposure to 30-90 mmol/LNaHCO 3 and all reached their minimum values with exposure to 90 mmol/L NaHCO 3. Under the latter stress, the rate of decrease in total chlorophyll content of 'C. ficifolia Bouch.' was higher than that of 'Chuandilong'. However, electrolyte leakage, MDA content, proline content, soluble sugar content and SOD and POD activities increased with the escalation of NaHCO 3 concentration and peaked after exposure to 90 mmol/LNaHCO 3. The rates of increase in electrolyte leakage and MDA contents of 'C. ficifolia Bouch.' were higher than those of 'Chuandilong' at this NaHCO3 concentration. These results suggested that under greater NaHCO 3 stress, these pumpkin cultivars showed significant inhibition of growth, with 'C. ficifolia Bouch.' being more sensitive than 'Chuandilong' to NaHCO3 stress. Injury caused by NaHCO 3 stress was most likely mitigated by increasing the antioxidant activities of SOD and POD and accumulating proline and soluble sugar contents to facilitate osmotic adjustment.