Seedling Vigor Research Articles

Impact of Foliar Application of ZnO and Fe3O4 Nanoparticles on Seed Yield and Physio-Biochemical Parameters of Cucumber (Cucumis sativus L.) Seed under Open Field and Protected Environment vis a vis during Seed Germination.

Nutritionally rich cucumber seeds remain in demand in the agricultural, health and cosmetic sectors as they are essential for a successful crop stand establishment and seed-based products. However, the production of cucumber seeds is impeded by source limitation and nutrient deficiency. The foliar application of micronutrients can supplement this deficiency and overcome the physiological setback. An experiment was undertaken to compare the impacts of the foliar application of Fe and Zn, as nanoparticles and fertilizers, on the yield and seed quality of cucumber under open and protected environments. A foliar spray of nano-ZnO (ZnNPs) and nano-Fe3O4 (FeNPs) at 100, 200 and 300 mg L-1, as well as ZnSO4 and FeSO4 as fertilizer (0.5%), was conducted at the vegetative stage and pre- and post-flowering stages. The NPs had a greater efficacy in an open field than in the protected (naturally ventilated poly house) environment. The application of both NPs increased seed yield (51.7-52.2%), total chlorophyll content (15.9-17.3%) and concentration of Zn and Fe in the fruit and the seed, by 2.0-58.5% and 5.0-30.5%, respectively. A significant increase in starch, soluble proteins, soluble sugars and oil content was observed in the seeds from the NP treated plants. NP treatment also enhanced the germination-related parameters, such as percent germination (16.8-17.0%), rate of germination (18.0-22.2%) and seedling vigor (59.8-72.6%). The biochemical characterization showed a significant improvement in the seed water uptake and the activity of hydrolytic enzymes (amylase and protease) in the germinating seed. The involvement of reactive oxygen species (superoxide anion and hydrogen peroxide) and antioxidant enzymes (Superoxide dismutase, Catalase and Peroxidase) in the germination process was indicated by an increase in their activities in the seeds from NP treated plants. Hence, the study proposes the potential benefit of the foliar application of 300 mg L-1 ZnNPs and 200 mg L-1 FeNPs at crucial stages of plant growth to improve the yield and seed quality in cucumbers.

Insect Pollinator’s Role in Fruit Setting of Prosopis cineraria (L.) Druce

Insect Pollinator’s Role in Fruit Setting of Prosopis cineraria (L.) Druce

Assessment of Germination Percentage and Seedling Vigour in Selected Maize Genotypes in Wukari, Taraba State, Nigeria

Assessment of seedling vigour in six selected maize (Zea mays L.) genotypes was evaluated in the screen house of the Department of Crop Production and Protection, at the Teaching and Research Farm of the Federal University Wukari, Taraba State during the 2020 and 2021 cropping seasons. The experiment was laid out in a complete randomized design (CRD) and replicated thrice. Seed vigour indicators were number of sprouting, mean emergence time, germination percentage, seedling fresh weight (g), seedling dry weight (g), seedling root length (cm), seedling vigour index I and seedling vigour index II. The seed matrices measured were hundred seed weight (g), seed width (mm), seed length and seed thickness (mm). From the results obtained, the strong, positive and significant (1.00) relationship between the 100 seed weight and seedling germination percentage indicated that, maize germination is mostly determined by its size. Further, the most effective high vigour indicators are root length, seedling length, germination percentage, mean emergence time and number of sprouting at 4 days. However, M1155 recorded the highest seedling (72.33), with the highest corresponding germination percentage of 98%.

Single and combined effects of fertilization, ectomycorrhizal inoculation, and drought on container-grown Japanese larch seedlings

Climate change can intensify drought in many regions of the world and lead to more frequent drought events or altered cycles of soil water status. Therefore, it is important to enhance the tolerance to drought and thus health, vigor, and success of transplantation seedlings used in the forestry by modifying fertilization and promoting mycorrhization. Here, we sowed seeds of Japanese larch (Larix kaempferi) in 0.2-L containers with 0.5 g (low fertilization; LF) or 2 g (high fertilization; HF) of slow-release fertilizer early in the growing season. One month later, we irrigated seedlings with non-sterilized ectomycorrhizal inoculum (ECM) or sterilized solution (non-ECM), and after about 2 months, plants were either kept well watered (WW; 500 mL water/plant/week) or subjected to drought (DR; 50 mL water per plant/week) until the end of the growing season. HF largely stimulated plant growth and above- and belowground biomass production, effects that are of practical significance, but caused a small decrease in stomatal conductance (Gs390) and transpiration rate (E390), which in practice is insignificant. ECM treatment resulted in moderate inhibition of seedling growth and biomass and largely canceled out the enhancement of biomass and foliar K content by HF. DR caused a large decrease in CO2 assimilation, and enhanced stomatal closure and induced senescence. DR also largely depleted foliar Mg and enriched foliar K. Although DR caused a large decrease in foliar P content in LF, it moderately increased P in HF. Likewise, DR increased foliar K in HF but not in LF, and decreased foliar P in ECM plants but not in non-ECM plants. Conversely, ECM plants exhibited a large enrichment in foliar P under WW and had a lower water potential under DR when grown in LF. These results indicate that the drought tolerance and health and vigor of Japanese larch seedlings can be modified by soil fertility and soil microorganisms. This study provides a basis for new multifactorial research programs aimed at producing seedlings of superior quality for forestation under climate change.

Plant Growth and Yield Response to Salinity Stress of Rice Grown under the Application of Different Nitrogen Levels and Bacillus pumilus Strain TUAT-1

Rice is an important food crop, and its production is significantly affected by salt stress under the changing climate. Soil-inhabiting microbial inoculants as well as efficient nitrogen (N) nutrition may have ameliorative effects on rice growth and yield under salt stress. However, the effects of the interaction between N application and microbial inoculants on the growth and grain yield of rice under salt stress is not yet fully understood. This study aimed to clarify whether the use of the Bacillus pumilus strain TUAT-1 biofertilizer, along with the right amount of N fertilizer, would alleviate salt stress in lowland rice production. We applied the Bacillus pumilus strain TUAT-1 as a biofertilizer in combination with different rates of N fertilizer: control (0% N), 2.64 g (NH4)2SO4 per nursery tray (100% N: the farmer-recommended amount), and 3.96 g (NH4)2SO4 per nursery tray (150% N). Salinity (100 mM of NaCl) was applied at the heading stage of rice plants in pot culture in the greenhouse, and the growth and yield components were accessed at harvest. In the nursery phase, the application of the biofertilizer TUAT-1 significantly increased seedling vigor and the root development of 21-day-old seedlings. Salinity stress at the heading stage significantly reduced chlorophyll content, panicle number, straw biomass, and grain yield; however, either the application of N alone or in combination with TUAT-1 ameliorated the salinity-related reduction in grain yield and yield component parameters. Plants receiving a high amount of N fertilizer (150% N) showed similar straw biomass and grain yield with or without TUAT-1 inoculation, regardless of saline or non-saline conditions. In both saline and control conditions, straw biomass and grain yield were higher in the plants inoculated with TUAT-1 than in those without TUAT-1. Specifically, the combined application of TUAT-1 and the farmer-recommended N level (100% N) led to an increase of 8% in straw biomass and 15% in grain yield under saline stress when compared with their respective plants without TUAT-1. Straw biomass and grain yield were similar in the (un-inoculated) plants grown under normal conditions and TUAT-1 + 100% N under salinity treatments, because TUAT-1 enhanced root development, which may promote soil nutrient uptake. Our results indicated that combined nursery application of TUAT-1 biofertilizer and 100% N fertilizer rate has the potential to boost the capacity of this bacteria to increase seedling vigor, which subsequently ameliorated the salt-induced reduction in the grain and straw yield.

Seed seedlings development of different Eucalyptus and Corymbia species purposing forestry advancements for Cerrado biome

The production of quality seedlings has a direct impact on the productivity of a forestry establishment. Knowing the specifics of each specie and its adaptation to the edaphoclimatic conditions of a given region is essential for the success of a forest plantation. The production of seedlings of Eucalyptus spp. and Corymbia spp. presented in this work comes from the sexual propagation, by seeds. The study carried out the comparison between 13 species of Eucalyptus spp. and Corymbia spp., verifying the quality of the seed lots, via in vitro germination test and by sowing in tubes. The biometric measurements applied in this study were total seedling height, stem diameter and vigor, two measurements of seedlings were carried out in plastic bags and the data were transferred to the R software to be analyzed, applying analysis of variance (ANOVA) and means of variables. The germination percentage was higher in tubes than the results obtained in vitro, with emphasis on the results of the species Eucalyptus dunnii, Corymbia citriodora, Eucalyptus longirostrata and Corymbia maculata, which reached 100% germination in tubes and these are also the species that stood out in biometric measurements, with emphasis on the results of the species Eucalyptus dunnii, Corymbia citriodora and Eucalyptus longirostrata. The study aimed to generate viable, healthy and vigorous seedlings from seminal propagules of Eucalyptus spp. and Corymbia spp., to compose, at the end of the experiment, which has the potential to extend, beyond this study, the Eucalyptus Garden at Escola de Agronomia - EA/UFG), Goiania, GO, Brazil, collaborating with the practical classes that will be able to use the space to present to the students the features inherent to the species.

Biocontrol potential of Streptomyces sp. M4 and salvianolic acid B produced by it against Alternaria black leaf spot

The proposed study was designed to evaluate the biocontrol potential of Streptomyces sp. M4 and its bioactive metabolites (culture cells/cell free culture supernatant/EtOAc extract/salvianolic acid B) against Alternaria black leaf spot disease. The antifungal metabolite salvianolic acid B attacked A. brassicicola caused fungal abnormalities viz. loss of pigmentation, lysed spores, distorted hyphae and leakage of cellular contents were observed under bright field and scanning electron microscope. The bioactive metabolites in the culture supernatant were found to be thermostable (up to 70 °C), photostable and also stable under acidic and basic conditions. In in vitro experiment, treatment of fungal infected seeds with M4 antagonists (20% of culture supernatant/cells/EtOAc extract/salvianolic acid B) resulted in 82–96% seed germination, 60.71–86.20% healthy seedlings and 1470–2067 seedling vigour as compared to pathogen infected seeds. In vivo pot experiment, in which fungal spores (A. brassicicola) infected Raphanus sativus seeds were treated with Streptomyces sp. M4 culture cells/culture supernatant/EtOAc extract/salvianolic acid B (100 μg/ml), showed increase in various agronomic traits and decrease in disease incidence rate (4–16%) as compared to pathogen treated seeds. In vitro and in vivo studies unveiled that the Streptomyces sp. M4 and its bioactive metabolites could be used as potent biocontrol agents against A. brassicicola infected plants and therefore, to increase the resistance power of plants against pathogens.

Sustainable organic substrate production using millicompost in combination with different plant residues for the cultivation of Passiflora edulis seedlings

The use of sustainable organic substrates of recognized quality is essential in the production of seedlings of fruit species. In this context, the present study aimed to formulate different sustainable organic substrates based on millicompost combined with different proportions of locally available organic waste, such as coconut fiber ( Cocos nucifera ) powder, gliricidia ( Gliricidia sepium) and elephant grass shavings ( Pennisetum purpureum) for the production of Passiflora edulis seedlings. The organic substrates used were as follows: S1- millicompost; S2- commercial substrate and substrates formulated based on millicompost: S3%–25% millicompost + 25% gliricidia + 25% elephant grass + 25% coconut fiber; S4%–50% millicompost+ 50% elephant grass; (S5) 50% millicompost+ 50% gliricidia; (S6) 50% millicompost+ 50% coconut fiber. At 56 days of sowing, the following morphological parameters were evaluated: shoot dry mass (SDM); root dry mass (RDM); plant height (PH); number of leaves (NL); stalk diameter (SD); root volume (RV); leaf area in cm 2 (LA); seedling vigor (SV) and clod stability (CS). The nutrient contents (N, P, K, Ca and Mg) accumulated in the shoot dry mass of the seedlings were determined after this period. The organic substrates that provided seedlings with significantly higher parameters (P <0.05) of SDM, RDM, PH, NL, SD, RV, LA, SV and CS were as follows: S1> S6> S5. The other substrates (S2, S3 and S4) presented seedlings with morphological parameters similar to each other. In addition, there was a greater accumulation of P, K Ca and Mg (P <0.05) in the shoot dry mass of the seedlings developed on the substrates S1> S6> S5. The substrates S6 and S5 represent two new options of sustainable substrates, being effective in the production of yellow passion fruit seedlings with excellent vegetative growth rates. • Millipedes are able to transform agricultural and urban waste into organic compost. • The use of millicompost in the cultivation of Passiflora edulis seedlings was evaluated for the first time. • The millicompost is efficient and has produced healthy and vigorous seedlings. • Organic substrates based on millicompost with powdered coconut fiber or gliricidia are efficient. • New organic substrate options for passion fruit seedling producers are available.

Pre-sowing enrichment of Echinacea angustifolia seeds with macronutrients improved germination performance and early seedling growth via stimulating the metabolism of reserves

Seed enrichment with macronutrients such as N, K and P through nutrient seed-priming is a low-cost and low-risk technique to improve seed vigor and proper establishment of early seedlings. The objective of this study was to assess the potential of nutrient-enrichment of Echinacea angustifolia seeds, a high-valuable medicinal plant in pharmaceutical industry, with NK, KP or NKP through seed-priming with KNO3, KH2PO4 and a mixture of KNO3 and KH2PO4, respectively, on seed germination indices and early growth of seedlings, relative to non-enrichment treatments (non- and water-priming). The data showed that vigor of NK-, KP- or NKP-enriched seeds improved when compared with non-enriched seeds, while the highest seed vigor was manifested by NKP-enriched seeds. This finding was supported by higher final germination percentage, germination rate indices, coefficient uniformity of germination and seedling vigor index, and less mean germination time observed for macronutrient-enriched seeds, especially for NKP-enriched seeds. Other evidence to support enhanced vigor of macronutrient-enriched seeds was increased activity of total dehydrogenase (an indicator for accessing seed viability and vigor) in NK-, KP- and NKP-enriched seeds, with the highest activity in NKP-enriched seeds. In addition, the growth of early seedlings obtained from NK-, KP- and NKP-enriched seeds increased relative to that of the seedlings obtained from non-enriched seeds, with the highest early growth for the seedlings originating from NKP-enriched seeds. The activities of α-amylase and β-amylase were stimulated in NK-, KP- and NKP-enriched seeds, with the highest stimulation being observed in NKP-enriched seeds. This finding was consistent with the highest total reducing sugars and total soluble sugars in NKP-enriched seeds. Therefore, pre-sowing enrichment of the seeds with NKP can be suggested to improve seed vigor and vigorous establishment of early seedlings in nutrient-poor soils.

Fluoride induces morphological change in Fenugreek (Trigonella foenum-graecum L) during germination and early seedling

The goal of this study was to assess the toxicological effects of exposing popular variety of fenugreek [Trigonella foenum-graecum L.] to fluoride during the germination and early seedling stages. In January 2022, the experiment was carried out at Arunachal University of Studies, Namsai. Surface sterilized seeds of uniform size were set for germination in petri-plates over cotton beds, treated with fluoride solutions of varied strengths (0.0, 2.0, 4.0 and 6.0 mM), made from a stock solution of sodium fluoride (50.0mM). The results showed that fluoride might cause considerable phytotoxicity during germination and seedling growth. Fluoride administration resulted 13 to 43.10% suppression of germination from 2.0mM to 6.0mM. Similar results were also found in germination index, germination energy, relative germination rate and seedling vigor index which were significantly reduced by 43.1, 43.1, 34.0, and 84.0% in 150.0 mM, respectively. Fluoride also had significant detrimental impact on seedling length (71.78%) in the intact seven days with increasing doses of fluoride.

Fluoride induces morphological change in Fenugreek (Trigonella foenum-graecum L) during germination and early seedling

The goal of this study was to assess the toxicological effects of exposing popular variety of fenugreek [Trigonella foenum-graecum L.] to fluoride during the germination and early seedling stages. In January 2022, the experiment was carried out at Arunachal University of Studies, Namsai. Surface sterilized seeds of uniform size were set for germination in petri-plates over cotton beds, treated with fluoride solutions of varied strengths (0.0, 2.0, 4.0 and 6.0 mM), made from a stock solution of sodium fluoride (50.0mM). The results showed that fluoride might cause considerable phytotoxicity during germination and seedling growth. Fluoride administration resulted 13 to 43.10% suppression of germination from 2.0mM to 6.0mM. Similar results were also found in germination index, germination energy, relative germination rate and seedling vigor index which were significantly reduced by 43.1, 43.1, 34.0, and 84.0% in 150.0 mM, respectively. Fluoride also had significant detrimental impact on seedling length (71.78%) in the intact seven days with increasing doses of fluoride.

Effects of damping-off fungus on seed germination of amaranth (Amaranthus Hybridus)

Seed borne pathogens are microorganisms that can prevent seed germination and cause serious threats to seedling development in the field. The research was conducted on the effects of damping off fungus on seed germination of Amaranth (Amaranthus hybridus) collected from some Agricultural farmland in Lapai Local Government Area of Niger State, North central Nigeria. The isolation of fungal species from Amaranthus hybridus seeds of the infected plants having symptoms of damping off disease using agar plate method and was identified using the morphological characteristics features from mycological atlas. Isolation from the infected seeds revealed that Rhizoctonia solani were associated with the plants. Seed weight (mg) and seed germination (%) were determined using the international rules for seed testing and the physiological seed quality indices were determined; these are germination index (GI), germination rate index (GRI) and seedling vigor index were arranged in Randomized Complete Block Design (RCBD) all in triplicates. The result indicated that seeds from uninfected plants recorded seed weight (8.97mg) as compared with the infected seeds (5.21mg), there was significantly higher germination (98.67%) observed in uninfected seeds compared with seeds of Amaranthus plants that were infected (32.13%) with damping off fungus. Germination index was observed to be higher in seeds of uninfected plants (9.34) and lower in seeds of infected plants (4.34). The significant effects observed of the fungus on both seed and seedlings are highly virulence on the infected plants. The research revealed that a very good association between Rhizoctonia solani causing damping off disease and seed germination failure of Amaranthus hybridus plants. In the cultivation of Amaranthus hybridus, seed weight, and physiological seed quality attributes should be considered for an effective damping off disease suppression.

Exploring Zinc and Boron Chemo-Priming Effects on Low-Vigour Seed Germination and Seedling Establishment of Sunflower (Helianthus annuus L.)

Poor germination and suboptimal seedling growth constitute as prime factors in lowering the achene yield and seed oil content of sunflower (Helianthus annuus L.), while chemo-priming with micronutrients might serve as a biological viable strategy provided source and dose optimization are performed. A trial was executed to appraise the comparative impact of seed priming with different doses of micronutrients like boron (B) and zinc (Zn) on sunflower germination and seedling growth traits of sunflower. The experiment was comprised of six treatments of B (0, 0.2, 0.4, 0.8, 1.6, 3.20 ppm) and Zn (0, 4, 8, 12, 16 and 20 mM) each, while seed germination, root and seedling growth related traits were taken as experimental variables. The results revealed that all treatments remained ineffective regarding seed germination and seed vigour of sunflower, while B and Zn doses of 0.2 ppm and 12 mM respectively, enhanced seedling emergence rate and vigour. The Zn (8 mM) significantly improved root length along with their fresh and dry weights, while all doses of B imparted antagonistic effects on root attributes. Likewise, Zn (8 mM) remained superior for shoot length, fresh and dry weights, while higher doses of B remained contra-productive for shoot growth of sunflower.

Seed Morphometry and Different Pre-sowing Treatments on Seed Germination of Spondias pinnata Linn. under Nursery Condition

The present investigation was carried out during 2018–19 to evaluate the variation in seed dimension and most promising seed pre-treatments for accelerating germination of Spondias pinnata Linn. The various pre-sowing treatments were the Control (no treatment); soaking in cold water for 24 hours; soaking in cold water for 48 h; soaking in cold water for 72 h; soaking in 100 ppm thiourea for 24 h; soaking in 200 ppm thiourea for 24 h; soaking in 400 ppm thiourea for 24 h; soaking in 800ppm thiourea for 24 h; soaking in 1000 ppm thiourea for 24 h; soaking in 100 ppm KNO3 for 12 h; soaking in 200 ppm KNO3 for 12 h; soaking in 400 ppm KNO3 for 12 h; soaking in 800 ppm KNO3 for 12 h and soaking in 1000 ppm KNO3 for 12 h. The experiment was laid out in randomised block design with 13 pre-sowing treatments and the control with three replications of 100 seeds. The highest (54.33%) germination percentage was observed from cold-water for 48 hrs followed by thiourea 1000 ppm for 24 hrs (50.00%) and potassium nitrate 200 ppm for 12 hrs (48.67%). Parameters like germination value, mean germination time, root length, shoot length and seedling vigour index were significantly different among all the pre-treatments.

Heterologous expression of a lycophyte protein enhances angiosperm seedling vigor.

Seedling vigor is a key agronomic trait that determines juvenile plant performance. Angiosperm seeds develop inside fruits and are connected to the mother plant through vascular tissues. Their formation requires plant-specific genes, such as BREVIS RADIX (BRX) in Arabidopsis thaliana roots. BRX family proteins are found throughout the euphyllophytes but also occur in non-vascular bryophytes and non-seed lycophytes. They consist of four conserved domains, including the tandem BRX domains. We found that bryophyte or lycophyte BRX homologs can only partially substitute for Arabidopsis BRX (AtBRX) because they miss key features in the linker between the BRX domains. Intriguingly, however, expression of a BRX homolog from the lycophyte Selaginella moellendorffii (SmBRX) in an A. thaliana wild-type background confers robustly enhanced root growth vigor that persists throughout the life cycle. This effect can be traced to a substantial increase in seed and embryo size, is associated with enhanced vascular tissue proliferation, and can be reproduced with a modified, SmBRX-like variant of AtBRX. Our results thus suggest that BRX variants can boost seedling vigor and shed light on the activity of ancient, non-angiosperm BRX family proteins.

Quality assessment of jabuticaba seeds when subjected to different temperatures

Jabuticaba is a typically Brazilian fruit, which can be found from the extreme south to the extreme north of the country, it can be used for various purposes, its commercialization ranges from in natura, industrial, pharmaceutical and cosmetics. In view of the above, this work aims to evaluate the influence of the size of jabuticaba seeds of the rajada variety, its germination potential, total seedling size, root and shoot length and seedling emergence, using different treatments. The extraction of the seeds was carried out by manually kneading the fruits against a flat and firm surface of a bench, so that they broke and exposed their seeds, soon after the mucilage was removed manually as well. After pulping, disinfestation was carried out using 1% sodium hypochlorite for three minutes, then triple washing with distilled water and arranged on paper towels, where they remained for 48 hours in the shade to remove excess moisture, separated according to diameters. To seeds to carry out the germination tests and the emergence speed index, when submitted to different treatments. In which it can be concluded that the size of the seed increases the germination potential of jabuticaba seeds, where larger seeds originate more vigorous seedlings, and should preferably be used for seedling production. The best treatment is the refrigerated one with a temperature of 5°C, as it presented a greater amount of seedlings throughout the days.

Enhancement of Seed Germination and Seedling Vigour through Different Seed Priming Treatments in Blackgram (Vigna mungo L.)

Background: Blackgram (Vignam ungo L.) is one of the most important legume crops, grown all around the world. It is used as a vegetable, feed, food and fodder purpose. Blackgram has lower germination and production because of its hard outer covering. To improve germination and seedling vigour, priming alters the physiological state of the seed. This change may improve germination uniformity, increasing seed vigour or physiology. Primed seeds generate seedlings that germinate faster and more uniformed than unprimed seeds and these early seedlings are frequently more robust and resistant to biotic and abiotic stresses. This is a time-saving and low-cost strategy that farmers may employ to improve crop stand and productivity while reducing cost. Methods: The experiment was carried out in 2016-2017 at Department of Genetics and Plant Breeding, SHUATS, Prayagraj. Blackgram (var. PU-31) seeds were primed with Hydro, Halo, Osmo and Organic priming at 12 hours. Then, four replications of the Complete Randomized Block Design were used to test seeds for germination and vigour. Result: The experimental results indicated that seed primed with PEG6000@ 20% had the highest germination, seedling length and vigour indices, followed by CaCl2@ 1%, when compared to control and other treatments.

Growth and Competitiveness of ALS-Inhibiting Herbicide-Resistant Amaranthus retroflexus L.

The evolved acetolactate synthase (ALS) inhibiting herbicide-resistant redroot amaranth has been confirmed in China and caused a great loss in soybean production. This study was conducted to evaluate the growth and competitiveness of ALS-resistant (R) and ALS-susceptible (S) redroot amaranth biotypes. Seeds of both R and S biotypes were subjected to different temperature regimes. Data revealed that the germination percentage and seedling vigor of both biotypes did not differ largely from each other at 10/20 to 30/40 °C. Under noncompetitive conditions, there were no significant leaf number, plant height, or dry weight differences between the R and S biotypes. Moreover, replacement series experiment results indicated that the R and S biotypes have a similar competitive ability. This study shows that there are no significant differences in growth or competitiveness between the R and S redroot amaranth biotypes regarding the physiological characteristics evaluated. Therefore, the proportion and distribution of the R biotype will not be affected in the absence of the ALS-inhibiting herbicide. Some other effective management practices should be adopted to cope with this troublesome weed.

Thermal amplitude of the air influences the emergence and vigor of seedlings of sour passion fruit

The sour passion fruit is an allogamous species which presents high genetic variability. It is being propagated commercially via seeds. The propagation of species through seeds can be affected by several factors such as the thermal amplitude throughout the day during the germination and the genetic characteristics of the individual. The objective of this study was to evaluate the germination and vigor of seedlings of genotypes of sour passion fruit under different thermal amplitudes of the air. The experiment was conducted in a germination chamber. The factorial scheme was 5 × 3, referring to the five thermal amplitudes of the air (25.0; 22.5-27.5; 20.0-30.0; 17.5-32.5 and 15.0-35.0 ° C) and three genotypes of sour passion fruit (BRS SC1, BRS GA1 and FB-200) in a completely randomized design with six replicates of 25 seeds per plot. The variables analyzed were percentage of velocity index, mean time of emergence, total length, shoot and root and dry mass of seedlings. The thermal amplitude close to 20.0-30.0 °C favored the emergence and vigor of sour passion fruit genotypes. The germination process and the biometric growth of the passion fruit seedlings are adversely affected in high thermal air amplitudes

Influence of differential root and shoot growth rate on seedling vigour index in rice

Early seedling vigour is an important trait in direct seeded rice which determines the growth and yield. It is a complex trait and is found to be associated with germination and seedling growth. The rice genotypes, BPT 5204 and PB 1850-27 were screened for early seedling vigour traits and the data was recorded on germination percentage, root length, shoot length, seedling length, seedling fresh weight and seedling dry weight. The seedling vigour index I and seedling vigour index II were calculated for both the genotypes. It was observed that seedling vigour index I and II was found higher in PB 1850-27 as compared to BPT 5204. The principal component analysis was done to study differential root and shoot growth rate in F1 plants with parents. It was observed that growth rate in F1 seedlings was found higher than both the parents. The root growth in F1 plants resemble BPT 5204 during initial days of germination, while shoot growth pattern exhibited similarity only with PB 1850-27. The F2 population exhibited segregation for mean root and shoot length.