Chlorophyll Fluorescence Values Research Articles

The effects of polyester microfibres on the development and seed yield of white mustard (Sinapis alba L.)

Microplastics are found in agricultural soils worldwide; however, little is known about the impacts of this ubiquitous pollutant on the growth and development of crops. Microfibres are one of the dominant microplastic types found in agricultural soils. Sources of microfibres in the agricultural environment are multiple, including soil amendment applications, wastewater irrigation and atmospheric deposition, with agricultural soils subsequently acting as an accumulating sink for plastics. A key consideration in an agricultural setting is yield; the seed yield is critical, as this is the part with economic value. This study investigates the influence of polyester microfibres, a prevalent type of microplastic in agricultural soils, on the growth and seed yield of Sinapis alba (white mustard). Polyester microfibres were added to soil samples at concentrations of 0.1% and 1% w/w, simulating environmental exposure levels. The study evaluated flower production, seed yield, pod-to-seed ratio, and chlorophyll fluorescence as indicators of plant health and reproductive success. Results revealed significant changes in chlorophyll fluorescence values (Fv/Fm), reduced flower production control (74 ± 37 flowers in the control, 31 ± 27 in the 0.1 treatment and 44 ± 31 in the 1 % treatment), and changes in pod-to-seed ratio (3.5 ± 0.65 seeds per pod in the control, 2.76 ± 0.5 seeds per pod in the 0.1% treatment and 2.83 ± 0.81 seeds per pod in the 1% treatment) in response to polyester microfibre exposure. Polyester microfibres were demonstrated to act as a stressor to S. alba, changing the chlorophyll fluorescence values, reducing the flower number, and in turn, reducing the pod-to-seed ratio. This study provides evidence that microfibres could reduce seed yield but that further research is required to elucidate the mechanisms by which these changes are occurring.

Transcriptome analysis of soybean roots in response to boron deficiency

Boron (B) deficiency is detrimental to Glycine max (L.) Merr., which is one of the leading oil crops. In this study, physiological analysis of soybean seedlings under B deficiency and control after 12 h, 24 h, 72 h and 8 days was carried out, and the roots were subjected to transcriptome sequencing analysis. The results showed that under B deficiency, the plant height, SPAD and chlorophyll fluorescence value of soybean seedlings decreased significantly, indicating that B stress significantly inhibited plant growth and photosynthesis. RNA-seq revealed a total of 5126 DEGs (Differentially Expressed Genes), and nine DEGs co-existed at the four-time points, among which GLYMA_03G130600 regulates transcription factor ORG3, which is related to plant growth. GO analysis revealed a total of annotated 4018 DEGs, among which the terms plasma membrane, extracellular, enzyme activity, ion transport metabolic process and oxidoreductase activity were significantly enriched at the four time points, which might hinder the growth of soybean and accelerate senescence. KEGG analysis showed that at level 1, the DEGs were mainly enriched in photosynthesis-related, phenylpropanoid biosynthesis, nitrogen metabolism and plant hormone signal transduction. At level 2 of secondary metabolism, the DEGs were mainly enriched in energy metabolism and amino acid metabolism pathways, which indicates that B stresses mainly affect photosynthesis, hormone regulation and amino acid metabolism of soybean, thus affecting plant growth. The above results give deeper insight into the soybean response to B deficiency and lay the foundation for further studies of the molecular mechanism of soybean response to boron deficiency.

Effects of sea-salt stress on morphological and biochemical indices of Grand Nain (Musa spp.) banana variety

Abstract Banana is cultivated abundantly in seaside regions, which are highly prone to rises in sea level or where seawater mixes with groundwater. This study aimed to investigate the effect of sea-salt stress on banana seedlings. Three different saline solutions, irrigation water, and distilled water were prepared for treatments; 15.3 dS m-1, 20.4 dS m-1, 25.7 dS m-1, 3.22 dS m-1 (irrigation water), 0.0 dS m-1 (control), respectively. Although there was no statistical difference in plant length after the treatment, plant diameter difference was observed in seedlings subjected to salt stress for 30 days. The most damaged leaves (4.8) were determined at the highest sea-salt solution (25.7 dS m-1). Compared with the root length (RL) results of control, irrigation water, and 15.3 dS m-1 treatments, the mean of RL was significantly higher in the 25.7 dS m-1 treatment (40.0 cm). Except for the 20.40 dS m-1 treatment, the other treatments had values close to each other. Contrary to the total chlorophyll (TC) and chlorophyll fluorescence (CF) values determined in control plants, the highest TC content and CF were found in irrigation water treatment with 34.8 mg g-1 Fw and 46.0, respectively. The levels of malondialdehyde (MDA) and proline were significantly higher in the 25.7 dS m-1 treatment than in the other treatments. Results demonstrated that the root length of the Grand Nain cultivar increased although the sea-salt stress had negative effects on plant morphology and biochemical content, indicating that it could adapt to short-term salt stress.

Influence of salinity and temperature on the growth, productivity, photosynthetic activity and intracellular ROS of two marine microalgae and cyanobacteria

Global Climate Change could change physical parameters in oceans, such as salinity and temperature. The impact of such changes in phytoplankton has not been well stated yet. In this study the effect of combination of three levels of temperature (20, 23, and 26 °C), and three levels of salinity (33, 36, and 39) on growth of a mixture co-cultivation of three common species from phytoplankton (one cyanobacteria, Synechococcus sp., and two microalgae, Chaetoceros gracilis, and Rhodomonas baltica), is monitored by flow cytometry under controlled cultivation conditions in a 96 h study. Chlorophyll content, enzymes activities and oxidative stress were also measured. Results demonstrate that cultures of Synechococcus sp. Exhibited a high growth at the highest temperature chosen in this study (26 °C) combined with the three selected salinity levels 33, 36, and 39. Nevertheless, Chaetoceros gracilis grew very slowly with the combination of high temperature (39 °C) and all salinities, while Rhodomonas baltica did not grow at temperatures higher than 23 °C. Maximum dry biomass and ash-free dry weight for the microalgal mixture were reached at salinity of 39 and temperature of 20 °C, the but highest chlorophyll fluorescence values were found at 30 salinity and 20 °C, decreasing as salinity and temperature increased.

The Integrated Application of Phosphorous and Zinc Affects the Physiological Status, Yield and Quality of Canola Grown in Phosphorus-suffered Deficiency Saline Soil

Despite the soil could contain high amount of phosphorus (P), salinity reduce its availability for crop plants. Hence, farmers should practice several tactics to ameliorate P deficiency in soils. The current study aimed to assess the importance of zinc (Zn) supply for mitigating the deficiency of P for canola grown in saline soil. The effects of three Zn rates (0, 150 and 300 mg L−1, Zn0, Zn150 and Zn300, respectively) under three P rates (0, 36 and 72 kg P2O5 ha−1, P0, P36, and P72, respectively) on physiological status, yield and quality of canola were measured. Treatments were arranged in the strip plot design based on completely randomized blocks with three replicates. Findings exhibited that P36 recorded the highest values of membrane stability index in the 2nd season, while statistically leveled P72 for relative water content and chlorophyll fluorescence in both seasons. Zn300 exhibited potent effect on all canola physiological traits in both seasons. In both seasons, P36 × Zn300, P72 × Zn150 and P72 × Zn300 showed the maximum chlorophyll fluorescence and performance index values. Plots treated with P72 achieved 70.0% increase in canola seed yield, greater than the untreated ones. Seed yield obtained with Zn300 were higher than Zn0 and Zn150 by1.30 and 1.10 times in 2019/20 season and 1.23 and 1.05 times in 2020/21 season. The highest oil % was recorded with P0 × Zn150 and P72 × Zn0 in the 1st season and with P72 × Zn150 in the 2nd season.

X-ray, multispectral and chlorophyll fluorescence images: innovative methods for evaluating the physiological potential of rice seeds

Abstract: Image analysis techniques are expanding in agriculture and, for being fast, simple, and not destroying samples, they are interesting alternatives in the detection of immature rice seeds. Therefore, the aim of this study was to evaluate the quality of rice seeds using X-ray, multispectral and chlorophyll fluorescence image analysis techniques. Initially, with the seeds identified and numbered, radiographic images were obtained to determine the free space (area between the endosperm + embryo and the glumes). Subsequently, with the same seeds used in the X-ray, multispectral and chlorophyll fluorescence images were acquired, and then the computerized seedling analysis was performed with the SVIS® software. It was concluded that rice seeds that do not germinate or originate abnormal seedlings have free space equal to or greater than 18.68%, higher reflectance in the spectral bands with wavelength from 590 nm to 780 nm (41.46% to 64.21%, respectively) and in the band of 970 nm (75.65%), in addition to having chlorophyll fluorescence values equal to or greater than 40.58 and 112.92 at excitation/emission energies of 630/700 nm and 645/700 nm, respectively.

The Effect of Chitosan on Plant Physiology, Wound Response, and Fruit Quality of Tomato.

In agriculture, chitosan has become popular as a metabolic enhancer; however, no deep information has been obtained yet regarding its mechanisms on vegetative tissues. This work was conducted to test the impact of chitosan applied at different plant growth stages on plant development, physiology, and response to wounding as well as fruit shape and composition. Five concentrations of chitosan were tested on tomato. The most effective chitosan doses that increased leaf number, leaf area, plant biomass, and stomatal conductance were 0.75 and 1 mg mL-1. Chitosan (1 mg mL-1) applied as foliar spray increased the levels of jasmonoyl-isoleucine and abscisic acid in wounded roots. The application of this dose at vegetative and flowering stages increased chlorophyll fluorescence (Fv/Fm) values, whereas application at the fruit maturation stage reduced the Fv/Fm values. This decline was positively correlated with fruit shape and negatively correlated with the pH and the content of soluble sugars, lycopene, total flavonoids, and nitrogen in fruits. Moreover, the levels of primary metabolites derived from glycolysis, such as inositol phosphate, lactic acid, and ascorbic acid, increased in response to treatment of plants with 1 mg mL-1- chitosan. Thus, chitosan application affects various plant processes by influencing stomata aperture, cell division and expansion, fruit maturation, mineral assimilation, and defense responses.

Phytoextraction of toxic elements and chlorophyll fluorescence in the leaves of energy willow (Salix sp.), treated with wastewater solids and wood ash

Open-field small plot long-term experiment was set up during 2011 with willow (Salix triandra × S. viminalis ‘Inger’), grown as a short rotation coppice energy crop in Nyíregyháza, Hungary. The sandy loam Cambisol with neutral pH was treated three times (2011, 2013, and 2016) with 15 t ha–1 municipal sewage sludge compost (MSSC) and with 600 kg ha–1 (2011, 2013) or 300 kg ha–1 (2016) wood ash (WA). In 2018 the MSSC-treated plots were amended with 7.5 t ha–1 municipal sewage sediment (MSS), and 300 kg ha–1 WA. MSSC and WA or MSS and WA were also applied to the soil in combinations during all treatments. Control plots remained untreated since 2011. Repeated application of wastewater solids (MSSC, MSS) and wood ash (WA) significantly enhanced the amounts of As (up to +287%), Ba, Cd (up to +192%), Cu, Mn, Pb, and Zn in the topsoil of willows. The combined application of MSSC+MSS+WA resulted in significantly higher Mn and Zn and lower As Ba, Cd Cr, and Pb concentrations in topsoil than MSSC+MSS treatment of soil without WA. Nitrogen concentrations in leaves of treated plants were generally slightly lower or similar to control. All soil treatments significantly enhanced the uptake or accumulation of nutrient elements (Ca, K, Mg, P) and potentially toxic elements (As, Ba, Cd, Cr, Cu, Mn, Ni, Pb, and Zn) in the leaves of willows during 2018, 2019, and 2020. Significantly higher Mn or Zn concentrations were measured in MSSC+MSS+WA than in MSSC+MSS treatments. Significant amounts of Cd (up to 1.11 mg kg–1) or Zn (up to 183 mg kg–1) can be translocated (phytoextracted) from a soil amended with wastewater solids or wood ash to willow leaves. In 2018 the treatments decreased the chlorophyll fluorescence values, while in 2019 and 2020 the light adapted fluorescence yield (Y) values were higher in treated than in control plants.

Efficacy of Isoproturon and Pendimethalin against Resistant Biotypes of spp. in Wheat ( L.)

Persistence of weeds under irrigation conditions is inevitable and manual management practices are labour intensive and cumbersome. As far as wheat is concerned huge losses in yield, are incurred due to spp. Therefore, the present study was carried out Rumex to evaluate the efficacy of herbicides against spp. during the 2017-18 at Department of Agronomy, Chaudhary Charan Singh Rumex Rabi, Haryana Agricultural University, Hisar (Haryana). Isoproturon as post- emergence and pendimethalin as pre-emergence were taken as treatments and applied at three doses (0.5X, 1.0X and 2.0X) under pot study 'X' is the recommended dose of herbicide@ 1000g/ha for isoproturon and 1500g/ha for pendimethalin .Four populations of spp. named as HHH (HAU Hisar), UPH (Ujha, Panipat), JHH (Jind) Rumex and JJR (Jhajjar) collected from putative resistance affected farmer's field.UPH and JHH populations are highly resistant whereas JJR population is moderately resistant to sulphonylureas herbicides. HHH population is sensitive so used as standard check for comparison. Majority of biotypes showed sensitivity against isoproturon at recommended dose except UPH biotype. It provided 70-90 per cent control to all biotypes at double of recommended doses. Lower values of plant height, chlorophyll fluorescence, fresh and dry weight were observed in isoproturon treated plants. biotypes were highly sensitive to pendimethalin when applied as pre emergence. It provided complete Rumex control to all biotypes. The information collected from this study will facilitate proactive management of spp. through sequential Rumexapplication of pre and post emergence herbicides.

Rooting and growth characteristics of ‘Maehyang’ strawberry cutting transplants affected by different growing media including decomposed granite

This study was conducted to examine the effects of different rooting media that include decomposed granite on the rooting characteristics and growth of strawberry cutting transplants. The six rooting media that were used in the experiment included coir (CO), mixed media (MIX, coir:perlite = 8:2, v/v), perlite (PL), decomposed granite 1–3 mm (GS), decomposed granite 3–5 mm (GM), and decomposed granite 5–9 mm (GL). The cuttings of strawberries were transplanted on January 4, 2021. Humidification was carried out for 14 days. At 14 days after cutting, a rooting rate of 100% was confirmed in all media. However, cutting transplants in GM and GL, which were quite large in particle size, showed a low likelihood of survival. At 28 days after cutting, the fresh weights of shoot and root were significantly higher in CO, as compared to the others, but the dry weights showed no significant differences regardless of the growing media. The root growth of strawberry cutting transplants showed the highest values in GS at 14 days after cutting (and end of humidification). However, at 28 days after cutting, the transplants in the CO medium showed better root growth than those in the other media. Chlorophyll fluorescence values (Fv/Fm) were decreased at 28 days after cutting in the GM and GL media. In conclusion, we found that GS has potential for use as a strawberry rooting medium.

The Effects of Foliar Application of Phenoxy and Imidazoline Family Herbicides on the Limitation of Primary Photosynthetic Processes in Galega orientalis L.

Fodder galega (Galega orientalis) is a perennial, wintering plant with great potential for agricultural development. The species has a large yield potential and exceptional adaptability to various environmental conditions. The sensitivity of G. orientalis to herbicides, however, as well as the photosynthetic performance of the species, are generally unknown. Our study aimed to evaluate the effects of the application of selected phenoxy herbicides (MCPA, MCPB) and the imidazoline family herbicide (IMA) on the parameters of primary photosynthetic processes as understood through fast chlorophyll fluorescence kinetics (OJIP). The effect of cultivation temperature was also investigated in the plants grown at 5, 18 and 25 °C. Time courses of OJIP-derived parameters describing photosystem II functioning after foliar application revealed that the plants showed negative responses to the herbicides in the order MCPB–MCPA–IMA within 24 h after the application. The application of herbicides decreased the values of maximum chlorophyll fluorescence (FM) and increased minimum fluorescence (F0), which led to a reduction in the maximal efficiency of PSII (FV/FM). Applications of MCPA and MCPB decreased variable chlorophyll fluorescence at 2 ms (VJ), 30 ms (VI) and VP, as well as the performance index (PIABS), which is considered a vitality proxy. The application increased absorption flux (ABS/RC), trapped energy flux (TRo/RC) and dissipated energy flux (DIo/RC). The effects were more pronounced in plants grown at 18 and 25 °C. The study revealed that the OJIP-derived parameters sensitively reflected an early response of G. orientalis to the foliar application of herbicides. Negative responses of PSII were more apparent in MCPA- and MCPB- exposed plants than IMA-exposed plants.

Enhanced Drought Tolerance of Arabica Coffee (Coffea arabica L.) by Grafting Method

The objective of this study was to evaluate grafting method to improve the drought tolerance of Coffea arabica. Using C. arabica species as scions, and C. robusta as rootstock, the grafted plant was compared with the non-grafted plant (C. arabica) under water deficit condition. The result shown that growth parameters such as plant height, leaf length, and leaf width of the grafted coffee plants were higher than those of the non-grafted. The leaf area, fresh and dry weight of plants were highly reduced in non-grafted coffee plants. The leaf chlorophyll content (SPAD) and chlorophyll fluorescence (Fv/Fm) values of the grafted and non-grafted coffee plants decreased significantly with increasing duration under water deficit condition. The SPAD and Fv/Fm values of the two coffee types were also increased significantly with increasing duration after re-watering. Compared to the non-grafted plants, higher values of SPAD, Fv/Fm and relative water content in the leaf were observed in the grafted coffee plants. Moreover, lower values of relative ion leakage were observed in the grafted coffee plants after three days of water withholding and one month after re-watering. On the other hand, the grafted coffee plants showed enhanced drought tolerance by reducing the percentages of wilting plant under water deficit condition, and increasing the recovery percentages after re-watering.

Evaluating herbicide resistance in Rumex spp. and its management in wheat (Triticum aestivum)

Wheat (Triticum aestivum L.) crop grown with rice-wheat cropping system is infested with complex weed flora. Rumex spp. is the major broad-leaf weed of wheat crop wherein the poor efficacy of recommended herbicides and likelihood of herbicide resistance has been noticed. Hence, two herbicides - metsulfuron (X dose- 4g a.i/ha) and halauxifen + fluroxypyr (X dose- 240 g a.i/ha) applied at three doses (0.5X, X and 2.0X) were evaluated against four populations of Rumex spp. in a pot experiment carried out at screen house of college of Agriculture, CCS HAU, Hisar during rabi 2017-18. One unsprayed control was also kept for each population and herbicide for comparison. Results indicated that majority of the Rumex biotypes have attained resistance against metsulfuron and were not controlled even at double of the recommended dose. Higher values of plant height, chlorophyll fluorescence, fresh weight and dry weight and lower value of electrical conductivity was observed in the herbicidal treatments showing comparatively less efficacy against this weed. All Rumex biotypes were found highly sensitive to halauxifen + fluroxypyr at recommended dose and recorded 85-90% visual mortality. The application of halauxifen + fluroxypyr is the best alternative option to manage this weed in problematic areas.

Particulate Matter Removal of Three Woody Plant Species, Ardisia crenata, Ardisia japonica, and Maesa japonica

In this study, we investigated the physiological responses and particulate matter (PM) abatement and adsorption of three plants: Ardisia crenata, Ardisia japonica, and Maesa japonica, to determine their effectiveness as indoor air purification. When compared to control (without plants), PM was significantly and rapidly decreased by all three plants. The reduction in PM varied by species, with A. crenata being the most effective, followed closely by A. japonica, and finally M. japonica. M. japonica showed the highest rate of photosynthesis and transpiration, generating the greatest decrease in CO2 and a large increase in relative humidity. We hypothesize that the increased relative humidity in the chamber acted in a manner similar to a chemical flocculant, increasing the weight of PM via combination with airborne water particles and the creation of larger PM aggregates, resulting in a faster sedimentation rate. A. crenata had a stomatal size of ~20 μm or larger, suggesting that the PM reduction observed in this species was the result of direct absorption. In the continuous fine dust exposure experiments, chlorophyll fluorescence values of all three species were in the normal range. In conclusion, all three species were found to be suitable indoor landscaping plants, effective at reducing indoor PM.

An attempt to the nondestructive investigation of photo-induced potato postharvest quality degradation – Preliminary results

AbstractAmong improper harvest and/or postharvest storage conditions, the effect of direct sunlight plays an important role in quality degradation of potato resulting in the development of green surface color based on chlorophyll formation associated with the formation of poisonous chemicals – glycoalcaloids – known as α-chaconine and α-solanine. Yellow skinned and fleshed potatoes with or without visible initial marks of green surface color were stored at normal room temperature under direct natural (sun)light conditions for almost two months. The aim of this study was the preliminary investigation of the sunlight induced formation of chlorophyll related compounds in potato indirectly by the detection of chlorophyll development. This attempt was based on nondestructive determination of chlorophyll related spectral and fluorescence indices for both sunlight exposed and unexposed potato sides. For both potato groups the chlorophyll content related DA-index® and chlorophyll fluorescence characteristics (F0, Fm, Fv and Fv/Fm) increased during the storage period representing chlorophyll formation. In the case of Fm, Fv and Fv/Fm values, the yellow samples reached the values of the initial spotted green samples by the 7th–9th days. From this time, the chlorophyll fluorescence values changed only minimally. After storage day 34, in the case of both at day 0 yellow and green spotted potatoes, the sunny side's F0 value was lower than that of shaded side. Close relationship was found between the results of Walz monitoring-PAM (Pulse Amplitude-Modulated) chlorophyll fluorometer and the PSI (Photon Systems Instruments) chlorophyll fluorescence imaging device (e.g. Fv R2 = 0.7226). According to our preliminary results, the Vis/NIR DA-meter®, the monitoring-PAM and the chlorophyll fluorescence imaging fluorometers were found to be suitable nondestructive devices for further investigations concerning the postharvest chlorophyll formation based greening phenomena, which is associated with solanine development in potato.

Particulate Organic Matter Distributions in the Water Column of the Chukchi Sea During Late Summer

AbstractTwo oceanographic cruises were completed in September 2016 and August 2017 to investigate the distribution of particulate organic matter (POM) across the northeast Chukchi Shelf. Both periods were characterized by highly stratified conditions, with major contrasts in the distribution of regional water masses that impacted POM distributions. Overall, surface waters were characterized by low chlorophyll fluorescence (Chl Fl < 0.8 mg m−3) and particle beam attenuation (cp < 0.3 m−1) values, and low concentrations of particulate organic carbon (POC < 8 mmol m−3), chlorophyll and pheophytin (Chl + Pheo < 0.8 mg m−3), and suspended particulate matter (SPM ∼2 g m−3). Elevated Chl Fl and Chl + Pheo (∼2 mg m−3) values measured at mid‐depths below the pycnocline defined the subsurface chlorophyll maxima (SCM), which exhibited moderate POC (∼10 mmol m−3), cp (∼0.4 m−1) and SPM (∼3 g m−3). In contrast, deeper waters below the pycnocline were characterized by low Chl Fl and Chl + Pheo (∼0.7 mg m−3), high cp (>1.5 m−1) and SPM (>8 g m−3) and elevated POC (>10 mmol m−3). POM compositions from surface and SCM regions of the water column were consistent with contributions from active phytoplankton sources whereas samples from bottom waters were characterized by high Pheo/(Chl + Pheo) ratios (>0.4) indicative of altered phytoplankton detritus. Marked contrasts in POM were observed in both surface and middepth waters during both cruises. Increases in chlorophyll and POC consistent with enhanced productivity were measured in middepth waters during the September 2016 cruise following a period of downwelling‐favorable winds, and in surface waters during the August 2017 cruise following a period of upwelling‐favorable winds.

Silencing MdGH3-2/12 in apple reduces drought resistance by regulating AM colonization

Drought leads to reductions in plant growth and crop yields. Arbuscular mycorrhizal fungi (AMF), which form symbioses with the roots of the most important crop species, alleviate drought stress in plants. In the present work, we identified 14 GH3 genes in apple (Malus domestica) and provided evidence that MdGH3-2 and MdGH3-12 play important roles during AM symbiosis. The expression of both MdGH3-2 and MdGH3-12 was upregulated during mycorrhization, and the silencing of MdGH3-2/12 had a negative impact on AM colonization. MdGH3-2/12 silencing resulted in the downregulation of five genes involved in strigolactone synthesis, and there was a corresponding change in root strigolactone content. Furthermore, we observed lower root dry weights in RNAi lines under AM inoculation conditions. Mycorrhizal transgenic plants showed greater sensitivity to drought stress than WT, as indicated by their higher relative electrolytic leakage and lower relative water contents, osmotic adjustment ability, ROS scavenging ability, photosynthetic capacity, chlorophyll fluorescence values, and abscisic acid contents. Taken together, these data demonstrate that MdGH3-2/12 plays an important role in AM symbiosis and drought stress tolerance in apple.

Seed Germination, Seedling Growth and Photosynthetic Responses to Temperature in the Tropical Tree Moringa oleifera and Its Relative Desert, Moringa peregrina

MORINGA oleifera and Moringa peregrine are cultivated in many areas in Almadinah Almunawwarah, western part of Saudi Arabia. The aim of the present study is to examine the responses of seed germination, seedling growth and photosynthetic performance for two Moringa species to different temperature treatments; 15/12°C, 25/22°C and 35/32°C; day/night. The obtained results indicated that seeds of both species could germinate at a wide range of temperatures with optimum temperature for highest percentage of germination, at 25°C. The results showed that most parameters of growth and the photosynthetic performances of the two species were highest at 25°C. However, the chlorophyll contents of M. oleifera and most values of chlorophyll fluorescence for both species were similar across the three temperature treatments. Additionally, the outcomes of this study showed that Moringa can be cultivated in many different regions with different temperatures.

Relationships of Brassica Seed Physical Characteristics with Germination Performance and Plant Blindness

Brassica oleracea is an important crop species that at early growth stages may exhibit failure of the apical growing point, an abnormality called “blindness”. The occurrence of blindness is promoted by exposure to low temperatures during imbibition and germination, but the causes of sensitivity to such conditions are unknown. We combined three analytical seed technology instruments to explore seed physical properties that are highly correlated with quality parameters and might be used directly for grading or sorting seed lots into subpopulations varying in potential susceptibility to blindness. For image analysis, we used the VideometerLab instrument, which can scan 19 wavelengths from ultraviolet to infrared and utilize that information in any combination to potentially identify unique criteria related to seed quality. The iXeed CF Analyzer was utilized to obtain chlorophyll fluorescence values for individual seeds. Chlorophyll contents of many seeds can be used as an indicator of seed maturity, a major contributor to seed quality. Finally, oxygen consumption measurements of individual seeds as obtained with the Q2 instrument are highly correlated with their performance under a wide variety of conditions. Six Brassica seed lots differed in their susceptibility to induction of blindness or loss of viability due to 48 h hydrated incubation at 1.5 ∘C. Analysis of physical and respiratory parameters identified some measurements that were highly correlated with the occurrence of blindness. Higher chlorophyll content, as detected by the CF-Mobile and certain wavelengths in the Videometer, was associated with greater occurrence of blindness or death following the induction treatment, suggesting that more immature seeds may be susceptible to blindness. Further research is required, but methods to detect and sort such seeds based on physical characteristics appear to be feasible.

Eco-physiological Responses of Amaranthus cruentus L. to Deficit Irrigation under Different NPK 20:10:10 Fertilization Rates

The aim of this research was to investigate the responses of Amaranthus cruentus L. to deficit irrigation under fertilization, in a 2 by 3 factorial experiment with two levels of irrigation (1.5 litre/week and 0.75 litre/week) corresponding to 2600 and 1300 mm/year respectively and three levels of NPK 20:10:10 (0, 138, 275 kg ha-1). This experiment was conducted in a screen house in Cameroon, and lasted for 12 weeks after the nursery phase. Growth parameters and chlorophyll fluorescence were measured weekly for 8 weeks. Destructive sampling was done at 12 WAT to determine biomass partitioning, water use efficiency and the root/shoot ratio. Data were analyzed for variance and relationships in the MINITAB Version 17 statistical package. Within each irrigation level, plant mass decreased as fertilizer rates decreased, while root: Shoot ratio increased instead. Plant mass expressed higher values at the higher irrigation levels while root: Shoot ratio was lower compared to that at lower irrigation levels. This shows a strategy for resource re-allocation to roots under both water and nutrient deficit. Harvest index was statistically similar across irrigation and fertilizer levels. Within the higher irrigation levels, WUE of plants decreased with a decrease in fertilizer rates but not for plants subjected to deficit irrigation. While chlorophyll fluorescence values differed significantly across treatments, all values were below 0.8, indicative of stress. Factor analysis showed that growth of A. cruentus was highly fertilizer-dependent, while chlorophyll fluorescence was irrigation-dependent. This suggest that fertilizer application is essential in ameliorating the effects of deficit irrigation, and will be essential in the production of this crop under deficit irrigation.