Multifarious Indigenous Diazotrophic Rhizobacteria of Rice (Oryza sativa L.) Rhizosphere and Their Effect on Plant Growth Promotion

A diverse group of rhizobacteria persists in the rhizospheric soil, on the surface of roots, or in association with rice plants. These bacteria colonize plant root systems, enhance plant growth and crop yield. Indigenous rhizobacteria are known to promote soil health, grain production quality and serve as sustainable bioinoculant. The present study was aimed to isolate, identify and characterize indigenous plant growth promoting (PGP) diazotrophic bacteria associated with the rhizosphere of rice fields from different areas of Jammu and Kashmir, India. A total of 15 bacteria were isolated and evaluated for various PGP traits, antagonistic activity against phytopathogens, production of hydrolytic enzymes and biofilm formation under in-vitro conditions. The majority of the isolated bacteria were Gram-negative. Out of 15 bacterial isolates, nine isolates produced IAA (12.24 ± 2.86 to 250.3 ± 1.15 μg/ml), 6 isolates exhibited phosphate solubilization activity (36.69 ± 1.63 to 312.4 ± 1.15 μg/ml), 7 isolates exhibited rock phosphate solubilization while 5 isolates solubilized zinc (10–18 mm), 7 isolates showed siderophore production, 8 isolates exhibited HCN production, 6 isolates exhibited aminocyclopropane-1-carboxylate (ACC) deaminase activity, 13 isolates exhibited cellulase activity, nine isolates exhibited amylase and lipase activity and six isolates exhibited chitinase activity. In addition, 5 isolates showed amplification with the nifH gene and showed a significant amount of nitrogenase activity in a range of 0.127–4.39 μmol C2H4/mg protein/h. Five isolates viz., IHK-1, IHK-3, IHK-13, IHK-15 and IHK-25 exhibited most PGP attributes and successfully limited the mycelial growth of Rhizoctonia solani and Fusarium oxysporum in-vitro. All the five bacterial isolates were identified based on morphological, biochemical and 16S rDNA gene sequencing study, as Stenotrophomonas maltophilia, Enterobacter sp., Bacillus sp., Ochrobactrum haematophilum and Pseudomonas aeruginosa. Rice plants developed from seeds inoculated with these PGP strains individually had considerably higher germination percentage, seed vigor index and total dry biomass when compared to control. These findings strongly imply that the PGP diazotrophic bacteria identified in this work could be employed as plant growth stimulators in rice.

Stability of Transgene Inheritance in Progeny of Field-Grown Pear Trees over a 7-Year Period

Breeding woody plants is a very time-consuming process, and genetic engineering tools have been used to shorten the juvenile phase. In addition, transgenic trees for commercial cultivation can also be used in classical breeding, but the segregation of transgenes in the progeny of perennial plants, as well as the possible appearance of unintended changes, have been poorly investigated. We studied the inheritance of the uidA gene in the progeny of field-grown transgenic pear trees for 7 years and the physical and physiological parameters of transgenic seeds. A total of 13 transgenic lines were analyzed, and the uidA gene segregated 1:1 in the progeny of 9 lines and 3:1 in the progeny of 4 lines, which is consistent with Mendelian inheritance for one and two transgene loci, respectively. Rare and random deviations from the Mendelian ratio were observed only for lines with one locus. Transgenic seeds’ mass, size, and shape varied slightly, despite significant fluctuations in weather conditions during cultivation. Expression of the uidA gene in the progeny was stable. Our study showed that the transgene inheritance in the progeny of pear trees under field conditions occurs according to Mendelian ratio, does not depend on the environment, and the seed vigor of transgenic seeds does not change.

A Physiological behavior and tolerance of Lactuca sativa to lead nitrate and silver nitrate heavy metals

This study goal to evaluate the effects of different concentrations of lead (Pb) and silver (Ag) on germination, initial growth and anatomical alterations of Lactuca sativa L. Plants use various mechanisms to reduce the impacts caused by anthropic action, such as xenobiotic elements of soils and water contaminated by heavy metals. These metals were supplied as lead nitrate and silver nitrate and the following treatments were established: control for both metals, maximum dose of heavy metals, for arable soils, allowed by the National Council of the Environment (Ag = 25 mg. Kg-1, Pb = 180 mg. Kg-1), double (Ag = 50 mg. Kg-1, Pb = 360 mg. Kg-1) and triple (Ag = 75 mg. Kg-1, Pb = 540 mg. Kg -1) of this dosage. Vigor and germination tests of the seeds and possible anatomical changes in the leaves and roots of lettuce plants were performed. The species showed a high capacity to germinate under Pb and Ag stress, and the germination was never completely inhibited; however, the germination decreased with increasing Pb concentrations, but not under Ag stress. The use of increasing doses of metals reduced seed vigor and increased chlorophyll content. An increase in biomass was also observed in plants from treatments submitted to Pb. The phytotoxic effects of metals were more pronounced at 15 days after sowing. Anatomically, L. sativa was influenced by metal concentrations, and had a reduction of up to 79.9% in root epidermis thickness at the highest Pb concentration, although some structures did not suffer significant changes. The results suggest that L. sativa presents tolerance to high concentrations of heavy metals, showing possible mechanisms to overcome the stress caused by these metals. In this research lettuce possibly used the mechanism of exclusion of metals retaining Pb and Ag in the roots preserving the photosynthetic apparatus in the aerial part of the plants. In general, the chemical element Pb was more toxic than Ag, in these experimental conditions.

Mobilization of seed storage proteins is crucial to high vigor in common bean seeds

ABSTRACT: Seed germination is a complex process controlled by many factors, in which physical and biochemical mechanisms are involved and the mobilization of reserves is crucial for this process to occur. Although, seed reserve mobilization is usually thought to be a post-germination process, seed reserve proteins mobilization occurs during germination. This study quantified seed proteins of bean genotypes during different hydration times, in order to understand the process of protein mobilization and whether there is relationship of this biochemical component with seed vigor. This study was conducted using seeds with different levels of vigor, genotypes with highest (13, 42, 55 and 81) and lowest (07, 23, 44, 50, IPR-88-Uirapurú and Iapar 81) physiological quality. High vigor genotypes showed greater efficiency in hydrolysis and mobilization of protein component, because they presented low globulins content in cotyledons at radicle protrusion in relation to low vigor genotypes (07, 23 and 50). The protein alpha-amylase inhibitor, observed in all genotypes, is involved with the longer time needed for radicle protrusion, according to the band intensity difference in genotypes 07, 44 and Iapar 81.

Pengaruh priming terhadap vigor benih kedelai (Glycine max (L.) Merril.) yang dikecambahkan pada media dengan cekaman alumunium

Kandungan aluminium yang tinggi pada tanah Ultisol merupakan salah satu masalah utama dalam budidaya tanaman kedelai mulai dari fase perkecambahan hingga pertumbuhan tanaman. Perlakuan priming pada benih diyakini mampu memperbaiki perkecambahan pada lingkungan yang kurang menguntungkan. Penelitian dilakukan untuk mengetahui pengaruh priming pada perkecambahan benih kedelai yang dikecambahkan dalam media masam dan mengandung aluminium. Penelitian disusun dalam Rancangan Acak Lengkap (RAL) pola faktorial. Faktor pertama adalah jenis priming : tanpa priming, H2O (air), KNO3 1%, KNO3 2%, GA3 50 ppm, GA3 100 ppm, dan PEG 6000 7,5%. Faktor kedua adalah varietas kedelai yaitu: Anjasmoro, Burangrang, dan Grobogan. Data dianalisis sidik ragamnya dan dilanjutkan dengan uji Beda Nyata Jujur (BNJ) 5% menggunakan program statistika R Studio. Hasil penelitian menunjukkan priming PEG 7,5% dan varietas Burangrang secara mandiri merupakan perlakuan terbaik untuk meningkatkan vigor benih kedelai berdasarkan variabel waktu muncul kecambah, kecepatan perkecambahan, dan panjang hipokotil. Implikasi penelitian ini adalah PEG 7,5% dapat digunakan untuk perbaikan perkecambahan pada tanah masam dengan kandungan aluminium yang relatif tinggi. High aluminium content in Ultisol is the main problem in soybean cultivation from germination to planting growth phases.Priming treatment is believed to improve seed germination in a poor-growing environment. This study aimed to determine the effect of priming of soybean seeds germinated under acid medium and aluminium stress. The experimental design used was Completely Randomized Design (CRD) with factorial pattern. The first factor was priming type : no priming, H2O (water), 1% KNO3, 2% KNO3, 50 ppm GA3, 100 ppm GA3, and 7.5% PEG 6000. The second factor was soybean variety : Anjasmoro, Burangrang, and Grobogan. The data obtained were analyzed using the R Studio statistic program with a 5% HSD test. The study resulted that each PEG 7.5% priming and Burangrang variety independently was the best in increasing soybean seed vigor based on sprout time emergence, germination speed and hypocotyl length. This research implicates that PEG 7.5% can be used to improve seed germination on acid soils with high aluminium content.

Application of WOA–SVR in Seed Vigor of High-Voltage Electric Field Treatment on Aged Cotton (Gossypium spp.) Seeds

When seeds are treated with a high-voltage electric field (HVEF) to improve seed vigor, due to the large differences in the biological electromagnetic effects on different types of seeds, the methods of variance analysis and regression analysis based on data statistics are generally used to construct the optimal electric field dose prediction model; however, the generalization performance of the prediction model tends to be poor. To solve this problem, the electric intensity, frequency and treatment time were taken as the input variables for hybrid support vector regression (SVR) analysis to establish the prediction model of the seed comprehensive germination index. The whale optimization algorithm (WOA) was used to optimize the kernel parameters of the SVR. The optimized hybrid WOA–SVR model predicted the optimal comprehensive germination index of aged cotton (Gossypium spp.) seeds to be 329, the optimal HVEF dosage was 3.64 kV/cm × 99 s, and the frequency was 1.4 Hz. The aged cotton seeds were treated with the optimal HVEF and the germination test was carried out. Compared with the check (CK), the comprehensive germination index of seeds increased by 48%. The research results provided a new method and new idea for the optimal design of parameters for seed treatment with HVEF.

SEED PRIMING AND EXOGENOUS APPLICATION OF SALICYLIC ACID ENHANCE GROWTH AND PRODUCTIVITY OF OKRA (Abelmoschus esculentus L.) BY REGULATING PHOTOSYNTHETIC ATTRIBUTES

Low and uneven germination is a serious problem for the successful production of okra seedlings. Priming of seeds as well as supplementation of different plant growth regulators exhibited better response in successful seedling production which eventually results in higher yield. Therefore, the present study was conducted to evaluate the effects of seed priming and exogenous application of salicylic acid (SA) on okra seed germination and plant development. The okra seeds were primed by 1 mM and 2 mM of SA for 60 minutes whereas the seeds were washed several times with distilled water for the control treatment. Similar doses of SA have been exogenously sprayed to the 12 days okra seedlings for 4 days. The results of the study revealed that seed priming with SA enhanced germination percentage (GP), increased coleoptile length and weight, shoot and root length, and seed vigor index (SVI). Similarly, exogenous application of 1 mM SA increased relative water content (RWC), contents of chlorophyll a, chlorophyll b, total chlorophyll while a higher dose of SA (2 mM) degraded the leaf pigments. Supplementation of SA altered photosynthetic attributes, net photosynthetic (Pn) and transpiration rate (Tr), stomatal conductance (Gs), and water use efficiency (WUE). Moreover, SA treatment reduced the time duration of flower bud initiation and days to first flowering and enhanced the yield per plant. The results of this study indicated that seed priming and exogenous application of SA enhanced germination and okra productivity by regulating RWC and photosynthetic attributes where 1 mM SA is more effective compared to 2 mM SA.

EFFECT OF ELECTROSTATIC FIELD ON SOYBEAN SEED GERMINATION PARAMETARS

The aim of this study was to examine the influence of electrostatic fields on seed vigor, mean rate of germination and coefficient of velocity of germination of five soybean genotypes. Testing was conducted at the Novi Sad Institute of Field and Vegetable Crops on the seeds of five soybean varieties: Sava, NS 2024, NS 1347, NS 3127, and NS Blackstar. The seeds were exposed to different values of direct current (DC) of the following voltage: 0 V (control), 3 V, 6 V and 9 V, to which the seeds were exposed for 0 min (control), 1 min and 3 min. After exposing the seeds to the electric field, the vigour index (VI), mean rate of germination (MGR) and coefficient of velocity of germination (CVG). The results show that the effect of the electrostatic field on seed vigour, mean rate of germination and coefficient of velocity of germination depends on the genotype, voltage and exposure time. The application of DC can be a suitable method for improving vigour index (VI), mean rate of germination (MGR) and coefficient of velocity of germination (CVG). In addition, the results indicate that it is necessary to adjust the DC treatment (voltage and duration of exposure of seeds) to a particular genotype, since inadequate treatments may deteriorate the quality of seeds. Keywords: electrostatic field, vigor index, MGR, CVG, soybean

Seed priming with Salicylic Acid (SA) and Hydrogen Peroxide (H2O2) Improve Germination and Seedling Growth of Wheat (Triticum aestivum) under Salt Stress

Aim: Salinity is a major barrier to successful crop production. Seed priming and exogenous application of different signaling molecules can efficiently confer salinity tolerance. Wheat is a major cereal crop in the world and salinity drastically reduces the wheat seedling growth and yield. Therefore, the present study was conducted to explore the potentiality of different signaling molecules such as salicylic acid (SA) and H2O2 to alleviate the salinity-induced growth inhibition of wheat. Place and Duration of the Study: The study was conducted in the Department of Seed Science and Technology, Bangladesh Agricultural University, from September-October, 2021. Methodology: The wheat (cv. BARI-Gom 24) seeds were soaked in normal tap water (hydro-priming), 1 mM SA, 2 mM SA, 0.1 mM H2O2, and 0.15 mM H2O2 solutions for 30 minutes. The untreated seeds were used as control. Eventually, primed seeds were exposed to 150 mM NaCl in Petri dishes during germination. Primed and non-primed seedlings were grown for 15 days under 150 mM NaCl stress condition. Results: The result revealed that salt stress significantly reduced germination percentage (GP), germination index (GI), seed vigor index (SVI), shoot and root length. The results also exhibited that photosynthetic pigments, total chlorophyll, carotenoids, lycopene, and beta-carotene contents were significantly reduced by salt stress. Seed priming with SA and H2O2 and hydro-priming promoted the germination percentage, seedling growth (including shoot and root length), SVI, and photosynthetic pigments. Conclusion: Pretreatment with 1 mM SA and 0.1 mM H2O2 was observed to be relatively more efficient in conferring salinity tolerance of wheat compared with other treating conditions. Overall, this study suggests that wheat seed priming with SA and H2O2 and hydro-priming can improve salinity tolerance. Aim: Salinity is a major barrier to successful crop production. Seed priming and exogenous application of different signaling molecules can efficiently confer salinity tolerance. Wheat is a major cereal crop in the world and salinity drastically reduces the wheat seedling growth and yield. Therefore, the present study was conducted to explore the potentiality of different signaling molecules such as salicylic acid (SA) and H2O2 to alleviate the salinity-induced growth inhibition of wheat. Place and Duration of the Study: The study was conducted in the Department of Seed Science and Technology, Bangladesh Agricultural University, from September-October, 2021. Methodology: The wheat (cv. BARI-Gom 24) seeds were soaked in normal tap water (hydro-priming), 1 mM SA, 2 mM SA, 0.1 mM H2O2, and 0.15 mM H2O2 solutions for 30 minutes. The untreated seeds were used as control. Eventually, primed seeds were exposed to 150 mM NaCl in Petri dishes during germination. Primed and non-primed seedlings were grown for 15 days under 150 mM NaCl stress condition. Results: The result revealed that salt stress significantly reduced germination percentage (GP), germination index (GI), seed vigor index (SVI), shoot and root length. The results also exhibited that photosynthetic pigments, total chlorophyll, carotenoids, lycopene, and beta-carotene contents were significantly reduced by salt stress. Seed priming with SA and H2O2 and hydro-priming promoted the germination percentage, seedling growth (including shoot and root length), SVI, and photosynthetic pigments. Conclusion: Pretreatment with 1 mM SA and 0.1 mM H2O2 was observed to be relatively more efficient in conferring salinity tolerance of wheat compared with other treating conditions. Overall, this study suggests that wheat seed priming with SA and H2O2 and hydro-priming can improve salinity tolerance.