Cherimoya (Annona cherimola Mill.) has an exceptional flavor and aroma, which makes it a fruit with great potential. However, little is known about its propagation by seeds. According to the scientific literature, the germination of cherimoya seeds is affected much more by external conditions than by internal conditions. Germination of cherimoya variety ‘Concha Lisa’ were tested for germination at constant temperatures of 25, 30, 40°C, and at room temperature, varying from 20-25°C, coupled with total darkness. Seeds were sown in Petri dishes (0.8% agar water), for 25 days of incubation. The kinetics of germination was determined according to five closely related parameters, viz. final germination percentage (FGP), mean germination time (MGT), coefficient of velocity of germination (CVG), time to 50% germination (T50) and seedling length (SL). The temperature of 30°C was found optimally suitable with 70.8% FGP, 17.5 days MGT and 3.91 cm SL, while the room temperature of 20-25°C slightly improved germination with only 25% FGP. Furthermore, significant decrease in FGP and SL was observed at 25°C and 40°C of temperature in comparison to 30°C. The analysis also revealed that cherimoya seed germination, day 10-15 after seed sowing is suitable for final counts. An overview on the emergence of cherimoya seedlings, during a 12-week period in pots is presented.
Shrubs and trees of the genus Ziziphus are a good example of naturally occurring multipurpose plant species with great potential in arid regions. This study was conducted to investigate the effect of cold stratification on seed germination and seedling growth of Ziziphus lotus (L.) Lam. Seeds were subjected to 0, 45, 90 and 120 days of cold stratification at 5°C. We also examined fruit, kernel and seed morphology. For each treatment period, four replicates of 50 seeds were incubated in plastic containers between two layers of moist sand at 15% and under greenhouse conditions for 15-day period. At the end of the experiment, the final germination percentage (FGP), shoot length and root length were assessed. The results clearly indicated that increasing duration of cold stratification improved seed germination. The most effective stratification period was 120 days where Z. lotus recorded 83% of FGP and 16.5 cm of total seedling length. Cold stratification treatments significantly increased shoot height, root length, as well as seedling total length. 120 days stratification treatment resulted in the highest shoot and root length (6.80 cm and 9.75 cm, respectively). An overview on the emergence of Z. lotus seedlings during a 15-day period was also illustrated.
Field experiments were conducted to investigate the response of common bean (Phaseolus vulgaris L.) to nitrogen fertilizer. The main factor included the fertilizer (Granular Urea 46% N), was made up of two levels: no fertilization (0 kg/plot: control) and fertilization (0.4 kg/plot), while the secondary factor was the variety (three varieties of common bean: Djedida, Nelson and Jalila). The experimental design was a randomized complete block design with split plot arrangement and replicated four times. The effect of fertilization was evaluated during two development stages (flowering and fruiting) for each variety and this on the total dry biomass, the length of the aerial and root parts, as well as on the number of secondary roots. On the other hand, the combined effect of fertilization and variety was studied on some yield parameters per plant, such as the number of flowers, pods, seeds and the harvest index. In addition, the number of nodules at the end of seed maturation was evaluated. The results indicated that the nitrogen fertilizer application significantly reduced the root length, the number of nodules and secondary roots in most of the common bean varieties. However, fertilizer application significantly increased dry matter in both flowering and fruiting stages, for the three studied varieties. Pod number per plant and seed yield was increased by the application of N fertilizer, depending on varieties and the parameters being measured. Djedida and Jalila varieties gave the best yield and can therefore be recommended to farmers. According to our results, the percentage of improvement by N fertilization on one parameter or another does not exceed an average of 20%, compared to the control. Indeed, the effect of fertilization is positive and seems to increase the harvest index by 18% in Djedida and by 20% in Jalila, compared to non-fertilized plants. Unfertilized plants of the variety Nelson showed the highest ability to nodulate.
The tree of heaven Ailanthus altissima (Mill.) Swingle is a multipurpose tree in forestry. However, it is considered an invasive and dangerous plant for native species, and in particular for national parks, where many studies have recorded their involvement in the disturbance of the already developed floral diversity. Assessing the impact of certain abiotic conditions on this species may identify the expected areas to be colonized by its seed propagation. Germination of tree of heaven were tested for germination at constant temperatures of 25, 30, 40°C, and at room temperature varying from 25-30°C coupled with total darkness. Seeds were sown in Petri dishes (0.8% agar water) for 6 days of incubation. The kinetic of germination was determined according to five closely related parameters viz. final germination percentage (FGP), mean germination time (MGT), coefficient of velocity of germination (CVG), time to 50% germination (T50) and seedling length (SL). For the saline condition, the seeds underwent various NaCl concentrations from 0, 50, 100 or 200 mM. For each treatment, there were four replicates with 50 seeds incubated in a plastic container between two layers of moist sand at 15% of the appropriate treatment and then placed in a culture chamber at 27°C (± 2°C) for 30-day period. The effect of temperature was not significant on the MGT, CVG and T50. However, it was significant (p< 0.0001) on FGP and SL. The maximum germination of 94% was obtained at a temperature of 30°C and the lowest FGP of 40% was obtained at 25°C. For the salinity effect, the FGP of 75% in the control was much higher compared to the seeds treated at 50 mM NaCl with only 17.2% of FGP. Germination was completely inhibited from 100 mM NaCl. A. altissima can be classified as sensitive to salt stress during seed germination and seedling emergence. The salinity effect then joined the temperature to monitor nature's A. altissima seed propagation
The Dragon tree, Dracaena draco (L.) L., is an extremely threatened species. Its natural regeneration is disturbed and population appears to decrease rapidly. To design appropriate germination and seedling establishment protocols for a species conservation and restoration program, we studied the effects of pre-soaking, substrate and light availability treatment on seed germination for 15-day period. The condition for light availability corresponded to the sowing depth (at surface or at 2 cm depth). Germination occurred better in the dark when seeds were sown at 2 cm depth. Our results showed that D. draco seeds sown in the sand under dark condition and after 24 hours pre-soaking in warm water germinated better and recorded 82.5% of final germination percentage (FGP). However, seedlings grew better in potting soil and recorded 54 mm of length. The maximum FGP of 51.3% was recorded under light condition. These results indicate that sowing depth and light availability could be a limiting factor for D. draco seed germination in natural condition. Furthermore, the establishment of D. draco seedlings (shoot and root length) during an 8-week period in pots was also assessed and illustrated. More research on seed ecophysiology is required to understand the mechanisms controlling seed germination of D. draco in arid and semi-arid conditions viz. salinity and drought.
The genus Callistemon belongs to the family Myrtaceae and comprises 34 species. They are woody aromatic trees or shrubs that are widely distributed in the wet tropics. According to the scientific literature, research on seed germination of this genus was rarely carried out. The germination requirements of Callistemon citrinus and Callistemon linearis were studied under controlled conditions in the laboratory. Seeds of both species were tested for germination at constant temperatures of 25°C, 30°C, 40°C, and at room temperature (23 ± 2°C) coupled with total darkness. Seeds were sown in Petri dishes (0.8% agar water) for 25 days of incubation. The kinetics of germination was determined according to four closely related parameters viz. final germination percentage (FGP), mean germination time (MGT), coefficient of velocity of germination (CVG) and time to 50% germination (T50). The room temperature of 23 ± 2 °C was found optimally suitable for both species, with 80% FGP and 11.1 days MGT for C. citrinus, and only 21.7% FGP and 12.4 days MGT were recorded for C. linearis. Furthermore, significant decrease in FGP was observed in both species at 25°C, 30°C and 40°C of temperature. The analysis also revealed that day 12-15 after seed sowing is suitable for final counts. Due of its very low FGP, seeds of C. linearis need an additional study to determine their viability.
The ability to reuse treated wastewater (TWW) would be of significant benefit to agriculture whilst at the same time providing a valuable water resource. This study concerned the effects of three various levels of treated wastewater (0%, 50% and 100% TWW) on seed germination and plant development of three different varieties of tomato (Lycopersicon esculentum) (viz. Toufan, Heinz and Bouzina). Irrigation with TWW persisted 15 days for the germination stage and 120 days for the growth and development stage. A control plot irrigated with a pure water (groundwater) was also set up in order to compare the seeds and the plants response to different concentrations of irrigation water. The final germination was expressed as a percentage of the total number of seeds in each treatment. This study has demonstrated that treated wastewater improves the germination in Heinz variety and had no effect on both Toufan and Bouzina varieties whether it is pure or diluted by half. For the growth stage, the statistical analysis showed that the Toufan variety has tolerated successfully the TWW irrigation with its high and moderate concentrations, and this by analysing all the morphophysiological parameters studied in this work (leaves numbers, stem and root length and dry biomass, relative water content and rate water loss).
Saline soils contain multiple types of salt, each of them may exert a different effect on seed germination and seedling growth. The aim of this study is to assess the effects of five types of salt on the seed germination and radicle establishment of common bean (Phaseolus vulgaris L. var. Djedida). The experiment was set out as a factorial experiment based on completely randomized design with four replications of ten seeds for the seed germination and twelve replicates for the seedling growth. We used five kinds of salts (NaCl, Na2SO4, CaCl2, CaCO3 and KCl) with concentrations of 0, 100, 200 and 300 mM. Seeds were incubated in Petri dishes at 25°C, in the dark, for 10 days. The results of analysis of variance indicated that the effects of salt types and concentrations, and their interaction effect were significant in all measured traits (P< 0.01). However, no significance effect was found on secondary roots number and seedlings dry biomass with CaCO3 treatment solution. According to the results, the inhibitory effects of the five salt types differed significantly. Indeed, germination of common bean seeds by various salts were in the order of NaCl > KCl > CaCO3 > Na2SO4 > CaCl2. However, the taproot length, the number of secondary roots and the seedlings dry weight by various salts were in the order of CaCO3 > KCl > NaCl > CaCl2 > Na2SO4. The effect of salt concentration was also obvious. The reduction in dry biomass of cotyledons is proportional to germination rates and to the development of seedlings in dry biomass and in size. Seeds of P. vulgaris var. Djedida were able to germinate under all concentrations of the various types of salt. The lowest final germination percentage (FGP) was obtained under 300 mM of all salts recording the following values: CaCO3 - 60%, NaCl - 60%, KCl - 52.5%, Na2SO4 - 50% and CaCl2 - 27.5%. During germination stage, the radicle emergence would be controlled by the environment osmolarity, while the later growth of the seedling would be limited by the reserve mobilization.
Soil salinity is one of the main abiotic constraints limiting plant growth. This paper focuses on the concept of internal adaptation in relation to salt tolerance during the vegetative phase. Under saline conditions, we evaluated some anatomical changes in stems (area, perimeter, cortex thickness, stele area, stele perimeter, pith area) and roots (thickness, cortex thickness and stele thickness) of two acacia species (A. karroo and A. saligna). Plants of 90 days old were cultured at various concentrations of NaCl (0, 200, 400 and 600 mM) for 21 days. The experiment was laid out in completely randomized design with four replications. For microscopic analysis, the stem tissues were cross-sectioned and the root were profile viewing. Results showed that salt caused remarkable changes in some anatomical-related parameters. Microscopic studies showed that every acacia species had made its own anatomical changes in stem and root by increasing/decreasing organ area, such as cortex thickness, stele thickness and pith area compared to control. In conclusion, under saline regimes, both species adapted specific characteristics of the roots and stems for better survival under saline environments.
A butterfly species, Danaus chrysippus (Linnaeus, 1758) (Lepidoptera Nymphalidae), also known as African Queen, is recorded for the first time in the arid region of Aïn Naga (Biskra, Algeria). Adults of D. chrysippus were recorded in a survey from October 2018 to February 2019 on their host plant Pergularia tomentosa (Milkweed) (Asclepiadaceae). Additional data on the life cycle and behavior of this species are given.
This paper describes the potential probiotic properties of a lactic acid bacterium. The evolution from a spontaneous fermentation to a directed one is realized with selected lactic starters which give many dairy products processing various organoleptic characters. The integration of new lactic acid bacteria strains isolated from diverse ecosystems is now used to increase the duration of bio-preservation of dairy products. Moreover, some lactic acid bacteria probiotic activity is exploited to produce functional food. The aim of this study is to research of the possible probiotic and technological potential with some preventive and therapeutic characteristics of some Lactobacillus species isolated from Algerian Raw Goat Milk. The selected isolate was identified to species level as Lactobacillus plantarum (58) using API 50CH Kits. Microbiological and biotechnological techniques were used to fulfill this work. Results obtained have shown that Lactobacillus plantarum (58) can resist to acidic, basic and enzymatic stresses. So, the former strain can be considered as a probiotic. Moreover, the inhibition activity of the Lactobacillus plantarum (58) against pathogens strains (Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25921, Bacillus cereus, Pseudomonas aeruginosa, Vibrio cholerae, Listeria ivanovii ATCC 19119 and Salmonella enterica) is clearly obtained by testing these strains with the direct method. Finally, Raw Goat Milk can be defined as an ecosystem that promotes the development of a microflora with probiotic characteristics.
The present work demonstrates the effects of moist cold stratification on seed dormancy breaking in Hawthorn (Crataegus monogyna Jacq.). We also examined the fruit and seed morphology. Mature and ripe fruits were collected, the pulp removed and the seeds (stones) left in the sun to dry for three days. Four temperature regimes viz. 4°C, 6.5°C (natural conditions where the fruits were harvested), 10°C and 20°C were used for stimulating seed germination under total darkness. For each treatment, there were four replicates with 50 seeds incubated in a plastic container between two layers of moist sand at 15%. At the end of the experiment, non-germinating seeds were tested for viability using Tetrazolium chloride (TZ). After 4 months, the final germination (FGP) was expressed as a percentage of the total number of seeds in each treatment. The fruits of Hawthorn were 14.9 ± 0.73 mm long and 15.1 ± 0.84 mm in diameter and weigh 2.05 ± 0.28 g. The seeds were 8.29 ± 0.43 mm long and 6.75 ± 0.39 mm in diameter and weigh (0.25 ± 0.04) g. The thousand-fruit weight was 2,000 g and of the thousand-seeds weight was 280 g. The statistical analysis indicated significant effect (p < 0.0001) of treatment on seed germination. Dormancy in this species was broken most effectively by cold stratification at 4°C and under natural conditions with 76% and 67.5% of FGP, respectively. Most of the nongerminated seeds of C. monogyna were viable (dormant) as judged by TZ.
Drought and salinity act simultaneously in tolerance and acclimatization under saline conditions. Therefore, plants subjected to these types of stress should have developed specific structural adaptations at the early stages of development. The solution to these environmental problems is to look for species that are relatively water-efficient and resistant to recurrent episodes of various abiotic stresses such as salt stress. In this study, the salinity tolerance index, ionic homeostasis and osmoprotection were evaluated in A. karroo and A. saligna plants of 90 days old and cultured at various concentrations of NaCl for 21 days. Results showed that salt caused remarkable changes in some growth-related parameters (dry biomass) represented by the salinity tolerance index (STI). Na+, Ca2+, and RatioNa+/K+ content in the leaves increased with salinity levels, while K+ contents were significantly reduced compared to the control in both acacia species. Levels of proline, total free amino acids and reducing sugars have been accumulated considerably in the leaves. A. karroo was more salt-tolerant than A. saligna. Our results showed that the adaptability of a species to salinity is closely related to ion selectivity and biomass production. The seedlings also accumulated significantly a set of important osmolytes in leaves under salt stress, showing a marked increase in secondary metabolite accumulation. This adaptation proved very specific to each species for better survival in saline environments.
Seeds of many tree-species possess a hard seed coat which is impervious to water. These seeds often take a long time to germinate, resulting in heterogeneity and a delay in seedlings development which is an inconvenience for reforestation success. The aim of the present work was to determine the possibilities to improve the germination of five leguminous trees of the genus Acacia that have been recorded in the arid and the desert region of Algeria using sulphuric acid. A duration of 30 min of immersion in sulphuric acid improved the seed germination up to 97.5% and 99% for A. albida and A. laeta, respectively. Increasing the time of immersion (from 30 to 90 min) improved the germination percentages for A. ehrenbergiana and A. seyal seeds to 92.5% and 93.7%, respectively. Increasing this duration to 120 min had a positive effect on A. tortilis seed germination, improving the final germination rate up to 97%. Understanding of seed Germination Requirements is very important for regeneration and successful tree establishment in forest nurseries as well as for direct plantation in arid and semi-arid lands.
Astragalus armatus Willd. subsp. armatus is an endemic shrub of the Northern Africa. Its cultivation and domestication are very limited because of difficulty with seed germination and establishment. In this study, we investigated some plant morphological characteristics in real time and in situ (leaves, fruit and seeds) of different ecotypes of A. armatus, collected from two sites in Algeria (Arid Steppe of Aïn Naga and Condorcet Moutain), which elevation and climate data are very different. Moreover, the role played by the seed coat in seed dormancy of these two different populations was tested by the effects of the pretreatment and its duration on the performance of seed germination, by considering the final germination percentage (FGP) and the mean germination time (MGT). These parameters are estimated for 10 days in Petri dishes and stored in darkness at (25°C). Pre-sowing treatments included immersion in concentrated sulphuric acid for 30, 60 and 90 min, and immersion in hot water (100°C) for 10 min. Statistical analysis showed that the treatment and the ecotypes effects on both FGP and MGT were highly significant (P< 0.0001). Untreated seeds of both ecotypes of A. armatus failed to germinate (except for a few of Condorcet Mountain ecotypes). For both populations, the most effective treatment was immersion in sulphuric acid for 60 minutes for the ecotype of Arid Steppe of Aïn Naga, and only 30 min for Condorcet Mountain. An excellent germinative strength is characterized by a higher FGP and a reduced MGT. The morphological characteristic and seed germination could be attributed to intraspecific variations resulting from the natural selection of the same species.
Breaking physical dormancy in some forest seeds is a challenge for scientists and forest managers to obtain a homogeneous germination for larger seed samples. The role played by the seed coat in seed dormancy of six trees with great interest in agroforestry (Robinia pseudoacacia, Leucaena leucocephala, Erythrostemon gilliesii, Styphnolobium japonicum, Acacia dealbata and Brachychiton populneus) was tested by the effects of the pretreatment and its duration on the performance of seed germination, by considering the final germination percentage (FGP) and the mean germination time (MGT). These parameters are estimated at various times of incubation (5, 10 and 15 days) in Petri dishes and stored in darkness at (25 ± 2°C). The pretreatment consists of an immersion of seeds in concentrated sulphuric acid during 30, 60 and 90 minutes. Sowing without pretreatment (control) revealed no germination induction for B. populneus and A. dealbata, except for R. pseudoacacia, L. leucocephala and S. japonica where the germination does not exceed 12% for all the experience duration. Generally, pretreatments were very useful to improve seed germination. The time of immersion into sulphuric acid significantly affected (P < 0.0001) the FGP and the MGT in all studied species. A duration of 30 minutes of soaking was adequate to give a very high rate of germination for L. leucocephala, E. gilliesii, S. japonica and A. dealbata with respective FGP of 100%, 95%, 100% and 82,5%. However, an extended duration of pretreatment of 60 minutes was necessary for a maximal germination for R. pseudoacacia and B. populneus with FGP of 85% and 100%, respectively. A prolonged duration of 90 minutes of presowing was very fatal for L. leucocephala, A. dealbata and B. populneus. An excellent germinative strength is characterized by a higher FGP and a reduced MGT.
Morphological studies (Total length from apical margin of clypeus to apex of elytra, width, body area and wing length) were carried out on the fourth larval instar, pupa and adult (male and female) of Henosepilachna elaterii (Rossi, 1794) (Coleoptera Coccinellidae) sampled from a Cucurbitaceae plant (Citrullus colocynthis Schrad.), which grow around the dam “Fountains of Gazelles” in Biskra (Algeria). The fourth instar larva and pupa measured 8.55 ± 0.20 mm and 2.56 ± 0.26 mm; 7.38 ± 0.36 mm and 4.81 ± 0.36 mm; length and width respectively. Adult beetles feeding on fresh leaves were hemi-spherical in shape and red ferruginous in color with 12 black spots on the elytra. Females measured 6.97 ± 0.25 mm in length and 5.37 ± 0.34 mm in width, while males were 6.17 ± 0.31 mm in length and 4.80 ± 0.37 mm in width. Duncan’s multiple range tests allowed us to classify specimens in increasing order of area as follows: 4th instar larvae 20.29 ± 0.15 mm2, adult male 26.41 ± 2.52 mm2, pupa 28.14±0.31 mm2 and adult female 31.73 ± 1.84 mm2. Moreover, the female wing was longer with a value of 10.07 ± 0.54 mm compared to the male, which recorded 8.72 ± 0.60 mm in length. Both adults and larva were serious pests of Citrullus colocynthis which resulted in skeletonisation of leaves.
The geographical distribution of the genus Acacia Mill. (Fabales Mimosaceae) in Algeria was determined after the prospect, localization and description of the various species populations overall Algerian territory. Twenty-four regions were prospected, based on relative species abundance. Among the ten-species found in Algeria, only A. karroo and A. saligna can be found in the whole country. However, there are some concentrations in certain northern regions. Acacia decurrens was only found in the Northeast, with high concentrations at the National Park of El Kala. Five of them are recorded in the southwest (A. albida, A. ehrenbergiana, A. nilotica, A. seyal and A. tortilis). Acacia farnesiana is indicated in the Northeast and the Northwest. Acacia laeta individuals were very rare. According to the climatic data during the years 2000-2016, the following species adapted to the annual pluviometry, that is lower than 100 mm: A. albida, A. ehrenbergiana, A. laeta, A. nilotica, A. seyal and A. tortilis. Three species (A. karroo, A. farnesiana and A. saligna) are in zones with an annual pluviometry between 250 and 500 mm). Acacia decurrens is located in a zone in which the annual precipitation exceeds 1000 mm. This study shows the distribution of the Acacia species in Algeria.
Acacia karroo is a leguminous tree listed in most of the Algerian territory. It is a salt-tolerant species and a multipurpose tree in agroforestry. However, the defence mechanisms underlying salt tolerance of this species are still unknown. In this study, the effects of salt stress on various morpho-physiological and biochemical traits of A. karroo were investigated. Three-months-old plants were submitted to increasing salt concentrations (0, 200, 400 and 600 mM NaCl), for a period of 21 days. Stem length was not significantly affected by salinity. Increasing salinity reduced the length of root. Number of leaves was maintained constant at 200 and 400 mM NaCl but was reduced slightly at 600 mM NaCl. Also, an increase in crown diameter by 30% under mild and high salt stress was observed. Furthermore, salt tolerance index was not affected at all salinity levels. The leaf mass area was not affected by saline conditions. Salt treatments did not produce a notable change in the relative water content of leaves, indicating a relatively high resistance as well to dehydration, which will certainly contribute to some degree of salt tolerance in A. karroo. Relative water loss from excised leaves was significantly higher at 200 mM and similar at high concentration of NaCl as compared to control. The result of variance analysis for the major effect of salinity showed that salt stress significantly decreased the content of photosynthetic pigment in leaves at higher concentrations of NaCl. However, at 200 mM of NaCl, an enhancement of chlorophyll b, total chlorophylls and carotenoids content was observed. At the same level, chlorophyll a presented a constant content compared with control. In conclusion, although plants suffered from salt stress, as shown by the degradation of photosynthetic, they continued their vegetative growth and maintained their internal water potential under salinity conditions. Therefore, A. karroo is a potential halophytic species to be cultivated in saline lands and make it favourable for agroforestry practices.
Acacia karroo Hayne is the most important woody invader of grassland in South Africa, and is one of the fastest-growing acacias, and produces high density wood. This study aims to compare the germinative behaviour of A. karroo seeds collected from two ecotypes geographically and climatically different (Coastal and Steppic area) in salt stress. The seeds were exposed to saline stress conditions by increasing concentrations of sodium chloride (NaCl) varying from 0 to 50, 100, 150, 200, 250, 300, 400 and 600 mM. Germination was estimated by the daily rates and the final germinated seed rate during a period of 21 days in Petri dishes at 25˚C (5 replicates of 20 seeds). The emergence of seedlings was appreciated by their overall length. The results revealed the existence of a significant variation (p < 0.001) between the two seed
sources. Indeed, those collected from an arid ecotype were most tolerant at higher sodium chloride concentrations. The response to salinity stress varied in time with NaCl concentration and seeds origin which could be attributed to intraspecific variations resulting from the natural selection of the same species.
Under 400 mM of NaCl, 20% of germination was obtained from the coastal seeds against 66% from the steppic seeds. The repeated measures analysis of variance also revealed a significant effect of factors “Concentrations of NaCl, ecotypes, time of germination and their correlation” on the kinetics of germination.