Taproot Length Research Articles

Overexpression of the Panax ginseng MYB4 gene enhances stress tolerance in transgenic Arabidopsis thaliana

The myeloblastosis (MYB) transcription factors are essential for plant stress responses. They can enhance plant tolerance to abiotic stresses (e.g., drought, salinity, and cold) via improved physiological and biochemical responses including the accumulation of metabolites. In this study, we constructed a Panax ginseng MYB4 (PgMYB4) gene expression vector and established the stable transgenic Arabidopsis thaliana lines to study the effects of this gene on plant stress tolerance. The germination rate and seedling taproot length were greater for the PgMYB4-overexpressing plants than for the wild-type plants. Accordingly, the overexpression of PgMYB4 in Arabidopsis enhanced seedling tolerance to drought, salt, and cold conditions. Under drought stress, the relative chlorophyll content decreased less, the proline content increased more, and the water loss rate decreased more in the transgenic plants than in the wild type. The expressions of stress-related genes responsive to dehydration 19A, responsive to dehydration 22, responsive to desiccation 29A, cold-regulated 15A, cold-regulated 47, and pyrroline-5-carboxylate synthase 1 were significantly upregulated in the transgenic Arabidopsis plants. Under high salt stress, the kinesin 1 (KIN1) expression was significantly upregulated in the transgenic plants. In response to the low temperature stress, the dehydration-responsive element binding protein 2A and KIN1 expressions increased dramatically in the transgenic Arabidopsis plants. Thus, PgMYB4 positively regulated the stress tolerance gene networks, which promoted the expression of anti-stress effector genes. This gene may be useful for ginseng breeding programs aiming to develop new cultivars with enhanced stress tolerance.

Root Traits Related with Drought and Phosphorus Tolerance in Common Bean (Phaseolus vulgaris L.)

Roots are key organs for water and nutrient acquisition and transport. Therefore, root phenes that are associated with adaptation to low phosphorus (P) environments could enhance top-soil exploration, while deeper allocation is important for acquiring water and mobile nutrients. The understanding of interactions among root phenes can help in the development of common bean (Phaseolus vulgaris L.) genotypes adapted to drought and low fertility through genetic improvement. Two experiments (pot and field) were conducted at the Agricultural Research Institute of Mozambique to assess the contribution of root phenes to common bean shoot biomass and grain yield under combined stress (drought and low P). The pot study assessed eight genotypes, with four treatments combining water regimes (drought and non-stress) and phosphorus levels (200 and 25) mg P kg−1 soil. In the field study, 24 common bean genotypes were also grown in high and low phosphorus (40 kg P ha−1 and without P application) under irrigation and limited water. The grain yield from fields under drought and P stress were correlated with the pot data on root traits. The response of root phenes to drought and phosphorus stress appeared to be related to the deep and shallow root systems, respectively. Deep rooted genotypes produced more total root biomass and high taproot lateral branching density, which resulted in high total root length under drought and low P stress, while shallow rooted genotypes had low total root biomass and less taproot lateral branching. Increased shoot biomass and grain yield under drought and low P was associated with higher mean values of taproot lateral branching density and total taproot length. Genotypes SER 125, BFS 81, FBN12111-66 and MER 22 11-28 showed a greater score of tap root branching density in the pot study with the highest grain yield in the field under low P and drought stress. Therefore, these can be recommended for use in low phosphorus and drought stress environment or serve as parents for improving phosphorus use efficiency and drought tolerance in common bean.

Pre-evaluation response of rhizosphere hybridization in acid lime

Rhizosphere hybridization is a new concept to secure the plant growth-promoting microorganisms to produce better nursery plants. Taking into the objective of rhizosphere hybridization, the present investigation was conducted in the secondary nursery block of ICAR-Central Citrus Research Institute, Nagpur. As many ten treatments consisting of rhizosphere microbes in form of water extract of the rhizosphere of acid lime, neem, bamboo, banyan and microbial consortium were tested in acid lime seedlings (cv NRCC Acid lime-7) raised on a solarized but containerized soil completely randomized design with three replications during 2018-20. Results showed a significant response to different treatments on plant growth parameters. In our study, the effect of the combined rhizosphere of banyan (Ficus benghalensis), neem (Azadirachta indica) and bamboo (Dendrocalamus strictus) was significantly superior to the rest of the treatments in increasing the biometric (seedling height, seedling diameter and number of branches per seedling), number of leaves per seedling, root architecture (tap root length, tap root diameter and number of secondary roots per seedling) and microbial biomass (fungal count and bacterial count) response of acid lime seedling compared to control treatment. Rhizosphere soil treatment was found to be superior over rhizosphere water extract treatment. Among various rhizosphere water extract treatments, acid lime rhizosphere water extract performed better in biometric response of acid lime seedling. Microbial consortium was observed to be better in increasing the microbial biomass of the rhizosphere, which could probably translate its response at later stages but added an additional resilience to rhizosphere, thereby, potentially effective in reducing the mortality once planted in main field.

Effect of Wood-derived Biochar as Growth and Development Medium for Kiwifruit Seedlings

Application of biochar as a soil amendment has gained attention as a sustainable technology for environmental remediation. However, information on its use as a growing medium amendment in Bhutanese context is presently unavailable. Hence, this study assessed biochar’s physical and chemical properties as well as the response of kiwifruit seedlings to biochar-amended media. Kiwifruit seedlings were grown in different locally available organic growing media containing different quantities of wood biochar. Seven different media namely: treatment 1 (compost, 100%), treatment 2 (wood biochar + compost, 25%: 75%), treatment 3 (wood biochar + compost, 50%: 50%), treatment 4 (wood biochar + compost, 75%: 25%), treatment 5 (wood biochar, 100%), treatment 6 (wood biochar + rice husk, 50%: 50%); and treatment 7 (wood biochar + vermicompost, 50%: 50%) were used. Treatments containing biochar recorded higher pH, implying biochar addition in acidic soil reduces liming need. Kiwifruit seedlings responded significantly to the biochar-amended medium as compared with the unamended controls. This was reflected in the plant growth parameters: plant girth, plant height, taproot length and the number of lateral roots. A significant effect (P≤0.05) in seedling girth (6.60 mm), height (68.60 cm), taproot length (44.40 cm), and lateral roots (25 numbers) was observed in treatment 2 (amended with 25% wood biochar). Likewise, medium prepared with 100% wood biochar (treatment 5) resulted in a minimum effect on all parameters. Our study reveals that biochar amendment can be a method for generating carbon offsets, but at quantities exceeding 25% of the total medium, no significant effect on the overall growth of plants is achieved.

Genetic dissection of drought resistance based on root traits at the bud stage in common bean.

A whole-genome resequencing-derived SNP dataset used for genome-wide association analysis revealed 196 loci significantly associated with drought stress based on root traits. Candidate genes identified in the regions of these loci include homologs of known drought resistance genes in A. thaliana. Drought is the main abiotic constraint of the production of common bean. Improved adaptation to drought environments has become a main goal of crop breeding due to the increasing scarcity of water that will occur in the future. The overall objective of our study was to identify genomic regions associated with drought resistance based on root traits using genome-wide association analysis. A natural population of 438 common bean accessions was evaluated for root traits: root surface area, root average diameter, root volume, total root length, taproot length, lateral root number, root dry weight, lateral root length, special root weight/length, using seed germination pouches under drought conditions and in well-watered environments. The coefficient of variation ranged from 11.24% (root average diameter) to 38.19% (root dry weight) in the well-watered environment and from 9.61% (root average diameter) to 39.05% (lateral root length) under drought stress. A whole-genome resequencing-derived SNP dataset revealed 196 loci containing 230 candidate SNPs associated with drought resistance. Seventeen candidate SNPs were simultaneously associated with more than two traits. Forty-one loci were simultaneously associated with more than two traits, and eleven loci were colocated with loci previously reported to be related to drought resistance. Candidate genes of the associated loci included the ABA-responsive element-binding protein family, MYB, NAC, the protein kinase superfamily, etc. These results revealed promising alleles linked to drought resistance or root traits, providing insights into the genetic basis of drought resistance and roots, which will be useful for common bean improvement.

Drought tolerance selection of GT1 rubber seedlings with the addition of polyethylene glycol (PEG) 6000

Abstract. Pasaribu SA, Basyuni M, Purba E, Hasanah Y. 2021. Drought tolerance selection of GT1 rubber seedlings with the addition of polyethylene glycol (PEG) 6000. Biodiversitas 22: 394-400. Tolerance of the rootstock of rubber to drought stress is not optimal. The root system can therefore be used as an indicator of drought tolerance to inhibit the growth of the plant. A good root system of rubber rootstocks is thought to help the plants acquire greater resistance to drought stress. Polyethylene glycol 6000 osmotic solution controls the water potential in the growing medium. This study aimed to analyze the effect of PEG 6000 osmotic solution (0%; 7.5%; and 15% concentration) on rubber seedlings leading to the development of morphological characters and sensitivity index. GT1 (Gondang Tapen 1) rubber seeds to be used as planting material were collected from the seed source garden of PT Socfin Indonesia. The study was carried out from January to February 2019, using a non-factorial randomized block design. The morphological characters observed were tapped root length, shoot height, the increased rate of taproot length, shoot height increase rate, ratio of taproot length, and shoot height. Data were analyzed using analysis of variance, discriminant, and drought stress sensitivity index. The results showed that the addition of PEG 6000 in planting media in vitro significantly influenced the character of the rate of increase of taproot length. The sensitivity index of taproot increase rate and the ratio of taproot length and shoot height was moderate at 7.5% levely contrast, the addition of PEG 6000 in planting media in vitro did not significantly impact it. The present study suggested that the rate of increase of taproot length was a distinguishing character showing the initial tolerance level of the GT1 seedlings to drought.

<i>In vitro</i> Germination and Early Vegetative Growth of Five Tomato (<i>Solanum lycopersicum</i> L.) Varieties under Salt Stress Conditions

In Senegal, tomato (Solanum lycopersicum L.) cultivation is affected by salinity in many agro-ecological zones. The selection of salt tolerant varieties would be an alternative solution to enhance the production. Thus, germination and growth are studied under axenic conditions for five varieties of tomato subjected to increasing concentrations of NaCl [0, 35, 70 and 105 mM], and supplemented in an MS/2 medium for 30 days. The results reveal that salt negatively affects the evaluated parameters. The Rodeo and Lady Nema varieties have the lowest final germination rates (50%) unlike the Mongal variety (55%). These last two varieties have a decrease of 71.78% and 81.28% in the height of the stem, respectively, in the presence of NaCl at [105 mM] while that of the Rodeo variety is 70%. The Xewel variety has the greatest average number of leaves in the presence of [NaCl 35 mM] (4.95 leaves) and [NaCl 70 mM] (4.77 leaves). The Lady Nema variety records the longest taproot length (2.99 cm) unlike the Rodeo variety (2.25 cm) at [NaCl 105 mM]. The Ganila variety reveals the highest number of secondary roots at the concentrations of [0, 35 and 105 mM] of NaCl with, respectively, 44.12, 29.25, and 4.25 roots. The Lady Nema variety records the highest fresh weight of aerial (0.055 g) and root parts (0.014 g) and the lowest root dry weights (0.0023 g). These results allow to conclude that the Lady Nema and Mongal varieties seem more tolerant, Ganila and Xewel are moderately tolerant and Rodeo is more sensitive to the presence of salt.

Respon Pertumbuhan dan Hasil Tanaman Wortel (Daucus carota L.) di Dataran Rendah pada Berbagai Volume Media dan Dosis Ampas Padat Biogas

This study aimed to determine the growth responses and yield of carrot (Daucus carota L.) grown at the lowland at various rates of biogas solid waste and media volumes. The experiment was carried out at Mataram University experimental field in Narmada, West Lombok, NTB with an altitude of 136 m above sea level, from April to July 2019. The experiment was designed according a factorialy Randomized Completed Block Design (RCBD). The first factor consisted of 4 volumes of the media which i.e: 2000 cm3/20 x 20 cm, 4000 cm3/25 x 25 cm, 5000 cm3/30 x 25 cm and 7000 cm3/30 x 30 cm. The second factor consisted of 3 levels of biogas solid waste (bio-slurry) with i.e: 10 tons/ha, 15 tons/ha, and 20 tons/ha. These two factors were combined resulted in 12 treatment combinations. Each treatment was repeated so there was 36 experimental units each with replicate. The results showed that the rates of bio-slurry affected the rate of increase in carrot leaf length and did not significantly affect the other parameters or yield of carrot plants in the lowlands. Rates of 10 tons/ha and 20 tons/ha produced a higher leaf length than 15 tons / ha. The media volumes influenced the rate of increase in leaf length, rate of increase in the number of leaves, plant fresh weight, dry tap root weight and tap root length. The media volume of 5000 cm3 and 7000 cm3 resulted higher growth and yield of carrot plants in the lowlands rates of the media volume of 2000 cm3 and 4000 cm3. There was no interaction between the bio-slurry rates and the media volumes in influencing the growth and yield of carrot plants in the lowland

Effect of Fertigation and Mulching on Root Studies and Crop Growth Indices for Seed Production in Okra [Abelmoschus esculentus (L.) Moench

Background: Okra is an important vegetable crop in India, Method of fertilization also plays an important role in supplying the nutrient to the plants because, the efficacy of fertilizers applied in soil being low due to various losses and fixation, mainly in area of problematic soil. Water and fertilizers are the two important inputs which are used scientifically and judiciously through precision farming technologies to increase productivity, profitability and nutrient use efficiency in okra seed yield and quality. Methods: The experiments were conducted during kharif 2016 and kharif 2017 to study the effect of precision farming technologies including fertigation and black polythene mulching to know the crop growth, yield, quality of seeds and root studies in okra seeds var. Arka Anamika and at ICAR-IIHR Hesaraghatta, Bengaluru. The experiment was laid out in RBD with three replication and four treatments each with mulch and on mulch viz., 100:50:75 N:P2O5:K2O kg ha-1 100:50:100 N:P2O5:K2O kg ha-1 T3-150:75:112.5 N:P2O5:K2O kg ha-1 T4- 150:75:150 N:P2O5:K2O kg ha-1 compared with soil application treatments. Result: Application of water soluble fertilizer @ T4-150:75:150 NPK kg/ha through fertigation either mulch (14.05q/ha) or non mulch (11.83q/ha) recorded significantly higher seed yield than fertilizer through soil application (9.92 q/ha).Similarly significantly higher value of Absolute Growth Rate (AGR) Crop Growth Rate (CGR) and root character were observed in the NPK fertigation treatment with or without mulch than the soil application of fertilizers (NPK soil application @ 100:50:100kg per ha (T9) and NPK soil application @ 150:75:150kg per ha (T10). Significantly higher root parameter tap root length (21.03cm), average length of primary roots (64.63cm), number of primary roots (10.83 nos), fibrous roots arising from main stem (26 nos) and root dry weight (23.07 g/plant) were recorded in the T4-150:75:150 NPK kg ha-1 through fertigation (WSF) with mulch than the fertigation without mulch and fertilizer applied through soil.

Mycorrhizas promote P acquisition of tea plants through changes in root morphology and P transporter gene expression

Tea (Camellia sinensis (L.) O. Kuntze) is predominantly grown in acidic soils with severe limitations of P-nutrition. The present study evaluated the effects of an arbuscular mycorrhizal (AM) fungus, Claroideoglomus etunicatum, on root morphology, leaf and root P concentration, phosphatase activity in soils and roots, and the relative expression of root P transporter genes (PT1 and PT4) in Camellia sinensis ‘Fuding Dabaicha’ seedlings in sands under two levels of P viz., 0.5 μM (P0.5) and 50 μM (P50) through Hoagland solutions (pH 4.2) for 24 weeks. Under both P0.5 and P50 conditions, AM seedlings displayed a higher growth performance (shoot biomass, root biomass, and plant height), root morphology (total length, taproot length, 2nd- and 3rd-lateral root number, and volume), and root-hair length, but lower root-hair density than non-AM seedlings. Mycorrhizal inoculation significantly increased root P concentrations in P0.5 and P50 and leaf P concentrations in P0.5 over non-mycorrhizal treatment. The AM seedlings recorded considerably higher soil acid, neutral, and total phosphatase activity under P0.5 treatment, and soil neutral and total phosphatase activity under P50 treatment, compared with the non-AM seedlings. Root acid phosphatase activity was reduced due to mycorrhization at both of P0.5 and P50. AM fungal inoculation up-regulated the relative expression of root CsPT1, while down-regulated the CsPT4 expression in P0.5 and P50 treatments. It was concluded that AM fungal inoculation significantly promoted P acquisition capacity of tea plants, especially in roots through improving root growth and enhancing soil acid phosphatase activity and root CsPT1 expression.

The environment temperature affects post-germination growth and root system architecture of pea (Pisum sativum L) plants

Seeds of ten different pea genotypes were sown in styrofoam transplant trays filled with vermiculite and kept in two different growth chambers, respectively at air temperatures of 10 °C and 15 °C. In both chambers the relative humidity was maintained at 90%, PPFD 180 μmol m−2 s−1and the photoperiod 12 h. At DAS 15 and 31, ten plant of each treatment were selected randomly, dissected and separated into roots and shoots. Root system was scanned and acquired root images were analyzed. Subsequently, all plant organs were dried (65 °C, 48 h) and weighed separately. Significant genetic variation was identified regarding root traits. Rather than with the drought resistance and N foraging capability the genetic variation was associated with P foraging capability of the root system. Despite significant genotype differences, root traits were remarkably affected by environment temperature. The suboptimum temperature reduced growth and delayed root development processes. The decrease of temperature from 15 °C to 10 °C was followed by a significant decrease in the dry matter of plant, but the ratio of root dry matter to plant dry matter was significantly increased. The total root length was also significantly decreased, almost totally due to a significant decrease in the lateral root length. Only slight effects were found regarding tap root length. Water and nutrient uptake capabilities of pea plants were enhanced under optimum temperature conditions, mostly due to increased lateral root density and extended root branching zone deeper into the soil. Either the differences in lateral root (LR) density or the length of branching zone seems to be related with the effects of temperature to the length of development time from LR initiation to LR emergence.

Effect of Different Size of Container on Growth and Quality of Seedlings of <i>Gmelina arborea</i> Roxb.

The study was carried out to find the effect of container size on the growth and quality of seedlings of Gmelina arborea . The seedlings raised in 17 × 13 cm poly bags showed better plant height, collar diameter and tap root length at all intervals, maximum leaf number at 100 and 140 DAS and were optimum for comparative biomass (fresh and dry) and seedling quality parameters followed by 300 cc root trainers in which the maximum number of lateral roots were recorded. The sturdiness and seedling quality have direct and positive relationship with container size and results revealed that container size had significant effect for most of the growth parameters.

Effect of growing media and GA3 on seed germination, growth and survival of Acid lime (Citrus aurantifolia Swingle) var. Kagzi seedling

A field experiment was carried out at Fruit Research Station Imalia, Department of Horticulture, College of Agriculture, JNKVV Jabalpur to assess the effect of growing media and GA3 on seed germination, growth and survival of Acid lime (Citrus aurantifolia Swingle) var. Kagzi. The treatments comprised five levels of seeds soaking in GA3 solutions and four different growing media were arranged thrice in Randomised Block Design. It was observed that the seed soaked with 150 ppm concentration of GA3 and growing media comprising soil + slurry enrich with Azotobacter significantly improve the parameters with regard to day taken to initiate germination, to attained 50% germination, germination at 30 days after sowing, height of shoot, stem girth, number of leaves, total length of seedling, fresh weight of shoots, dry weight of shoots, fresh weight of roots, dry weight of roots, length of taproot, number of secondary roots, seedling vigour index I, seedling vigour index II, survival percentage of seedling. The higher value of physiological parameter were also recorded with seed soaked with 150 ppm concentration of GA3 and growing media comprising soil + slurry enrich with Azotobacter individually.

Effect of Growing medium, Fertilization and Biostimulant treatments on Growth and Flowering of Potted Gerbera (Gerbera jamesonii cv. Jaguar Yellow)

The current study was aimed to investigate the effect of different fertilization and biostimulant treatments on growth and flowering of Gerbera (Gerbera iamesonii cv. Jaguar Yellow) plant under unheated plastic greenhouse conditions. This study was carried out for two successive seasons of 2016/2017 and 2017/2018 at the farm of the Arid lands Agriculture graduated studies and Research Institute (ALARI), Shobra Elkheima area, Qalyobia governorate, Egypt. The experiment were laid out in a completely randomized design (CRD) with 3 replications, and the end results have been subjected to analysis of variance (ANOVA). Freshly extracted gerbera seedling have been planted into pots filled with peatmoss + sand (1:1), peatmoss + sand + vermicompost (1:1:1), peatmoss + sand + compost (1:1:1) with or without 250ml of Azotobacter + Azospirllum mixture, as biostimulant, and slow-release NPK (4.2g) or fast-release NPK (2.5g) fertilizers to each plant, to determine the effect of fertilizer, biostimulant and growing medium types on the production of potted gerbera. Growth and flowering characteristics were measured. Results indicated that medium combination of sand + vermicompost + peatmoss (1:1:1) with biostimulant, regardless of the fertilizer type, gave significantly increased results in all measurements, compared to all other combinations. Plants grown in medium supplemented with biostimulant and fast-release fertilizer, gave flowers with good qualities While the medium combination sand + vermicompost + peatmoss (1:1:1) with biostimulant in combination with either one of NPK mineral fertilizers (fast-release fertilizer and slow release fertilizer) gave significantly increased results in most parameters, shown in higher total vegetarian and quality when combined with slow release fertilizer than fast-release fertilizer. Under this treatment, plant length was (28.2 cm), number of leaves per plant was (24.8), stem diameter was (3.7 mm), fresh weight (47.9 g), seedings dry weight (12.5g), length of the longest tap root was (19.8 cm), diameter of tap root (2.9 mm), number of secondary roots (40.7), root/shoot ratio (2.57), Leaf greenness SPAD 59, and the highest number of daughter plants (5.3/plant). These records were all significantly higher than other treatments

Effects of lime and coffee husk compost on growth of coffee seedlings on acidic soil of Haru in Western Ethiopia

A pot experiment was conducted to determine the effects of lime, coffee husk compost and their combinations on growth response of coffee ( Coffea arabica L.) seedlings at Haru Research Sub-Center nursery site in West Ethiopia in 2016/17. The experiment was laid out in a factorial experiment arranged in Randomized Complete Block Design with three replications. The treatments included four levels of lime (0, 2, 4 and 6 g/2.5k g soil (pot)) and coffee husk compost (0, 6.25, 12.5 and 18.75 g/2.5 kg soil (pot)). The relevant shoot and root growth parameters data were collected and subjected to Analysis of Variance using SAS package and treatment means were compared at 0.05 probability using Duncan’s Multiple Range Test. The results revealed that lime and coffee husk compost rates significantly (p ≤ 0.01) affected the shoot and root growth of coffee seedlings. The highest growth performance of coffee seedlings (plant height, stem girth, leaf number and area, tap and lateral root length, lateral root number, root volume, stem, leaf and root dry matter) were obtained from the application of 18.75 g/pot coffee husk compost and combined lime and coffee husk compost at the modest levels of 4g/pot lime and 12.5 g/pot coffee husk compost with a non-significant variation. From the study, it can be concluded that application of 18.75 g/pot coffee husk compost or combining 12.5 g/pot of coffee husk compost and 4 g/pot of agricultural lime could be a promising alternative amendment for acid soil management and production of vigorous coffee seedlings in Haru areas. But, further investigations should be continued under field conditions across locations and seasons to evaluate the effects of liming and coffee husk composts in ameliorating soil acidity, and improving growth, yield and quality of coffee varieties and establish their profitable levels for sustainable soil fertility management and production of Wollega coffee in west Ethiopia.

A Novel Graft between Pac Choi (Brassica rapa var. chinensis) and Daikon Radish (Raphanus sativus var. longipinnatus)

Vegetable grafting has primarily been used in the commercial production of high-value crops in the Solanaceae and Cucurbitaceae families. In this study, we explored the feasibility of making a novel graft between pac choi (Brassica rapa L. var. chinensis) and daikon radish (Raphanus sativus L. var. longipinnatus) to create a plant with harvestable pac choi leafy vegetable above-ground, and a daikon radish taproot below-ground. ‘Mei Qing Choi’ pac choi (scion) was grafted onto ‘Bora King’ daikon radish (rootstock). Grafted pac choi–daikon radish plants did not show a decrease in SPAD value, canopy size, leaf number, leaf area, or above-ground weight compared with self-grafted pac choi plants. However, taproot formation was reduced in grafted pac choi–daikon radish plants, as shown by decreased taproot length, diameter, fresh weight, and dry weight compared with non- and self-grafted daikon radish plants. Surprisingly, grafting with radish increased the photosynthetic rate of the pac choi. This pilot study demonstrated the potential of creating a new pac choi–daikon radish vegetable product to help save growing space and minimize waste at consumption, as pac choi roots are not eaten and radish leaves are usually discarded. The inter-generic grafting between B. rapa var. chinensis and R. sativus var. longipinnatus could also provide a unique model system to help elucidate scion-rootstock synergy and above- and below-ground sink competition in horticultural crops.

Bacillus amyloliquefaciens PDR1 from root of karst adaptive plant enhances Arabidopsis thaliana resistance to alkaline stress through modulation of plasma membrane H+-ATPase activity

Exploration of native microbes is a feasible way to develop microbial agents for ecological restoration. This study was aimed to explore the impact of Bacillus amyloliquefaciens PDR1 from karst adaptive plant on the activity of root plasma membrane H+-ATPase in Arabidopsis thaliana. A. thaliana was cultured in presence or absence of B. amyloliquefaciens PDR1 and its effects on the growth were evaluated by measuring the taproot length and dry weight. The rhizosphere acidification capacity was detected by a pH indicator, a pH meter and non-invasive micro-test techniques (NMT). The nutrient uptake was performed using appropriate methods. A combination of transcriptome sequencing and real-time quantitative polymerase chain reaction (qRT-PCR) was used to measure the expression of functional genes that regulate the plasma membrane H+-ATPase activity in A. thaliana roots. Functional analysis was performed to understand how B. amyloliquefaciens regulates biological processes and metabolic pathways to strengthen A. thaliana resistance to alkaline stress. Here, we show that volatile organic compounds (VOCs) from B. amyloliquefaciens PDR1 promoted the growth and development of A. thaliana, enhanced the plasma membrane H+-ATPase activity, and affected ion absorption in Arabidopsis roots. Moreover, B. amyloliquefaciens PDR1 VOCs did not affect the expression of the gene coding for plasma membrane H+-ATPase, but affected the expression of genes regulating the activity of plasma membrane H+-ATPase. Our findings illuminate the mechanism by which B. amyloliquefaciens regulates the growth and alkaline stress resistance of A. thaliana, and lay a foundation for wide and efficient application for agricultural production and ecological protection.

Functional polymorphism among members of abscisic acid receptor family (ZmPYL) in maize

Pyrabactin resistance 1-like proteins (PYLs) are direct receptors of abscisic acid (ABA). For the redundant and polymorphic functions, some members of the PYL family interact with components of other signaling pathways. Here, 253 positive colonies from a maize cDNA library were screened as interacting proteins with the members of ZmPYL family. After sequencing and function annotation, 17 of 28 interaction combinations were verified by yeast two-hybrid (Y2H). The germination potential, taproot length and proline content of a quartet mutant of Arabidopsis PYL genes were significantly deceased comparing to the wild type (WT) under alkaline stress (pH 8.5) and 100 µmol L−1 methyl jasmonate (MeJA) induction. The malondialdehyde (MDA) content was significantly increased. After germinating in darkness, the characteristics of dark morphogenesis of the quartet mutant seedlings were more obvious than those of the WT. The differential expression of the related genes of photomorphogenesis in the mutant was much more than that in the WT. Three light and two JA responsive cis-affecting elements were identified during the promoter sequences of the AtPYL1 and AtPYL2 genes. These results suggested that functional polymorphism has evolved among the members of ZmPYL family. In response to developmental and environmental stimuli, they not only function as direct ABA receptors but also interact with components of other signaling pathways mediated JA, brassinosteroid (BR), auxin, etc., and even directly regulate downstream stress-related proteins. These signaling pathways can interact at various crosstalk points and different levels of gene expression within a sophisticated network.

Influence of Seed Size on Seedling Emergence, Growth and Yield of Potted Groundnut (Arachis hypogea L.)

Pot experiments were conducted at the Faculty of Agriculture, Kogi State University, Anyigba, Kogi State in the Southern Guinea savannah ecological zone of Nigeria to evaluate the influence of seed size on plant performance with reference to seedling emergence, seedling growth, development and yield components and yield of groundnut (Arachis hypogea). The treatment consisted of three different seed sizes: small, medium and large seeds apportioned to a Randomized Complete Block Design (RCBD) with ten replications. For seed size, the seeds were initially graded into small, medium and large seeds based on visual assessment for length and diameter and from each group 100-seed weight was determined thus 100-seed weight became the parameter for measuring seed size as used in this experiment. The analyzed data showed no significant effect of seed size on groundnut canopy height, leaf number, leaf area, stem girth, days to first flower, number of pods / plant, pod weight, and shelling percentage, but significantly influenced mean days to seedling emergence, days to 50 percent flowering, 100-seed weight and taproot length. The significant effect of seed size on days to seedling emergence, days to 50 percent flowering, 100-seed weight and taproot length could significantly influence farmers’ opinion in the choice of seeds used in planting a field; as this could determine crop maturity, grain yield/ha while length of tap root could affect depth of root forage for nutrients and water, thus crop survival. Despite the non-significant effect of the treatment (seed size) on most parameters investigated, generally crop performance increased with seed size and vice versa, thus sowing of larger seeds is recommended for better groundnut performance.

Root Foraging Capacity in Bambara Groundnut (Vigna Subterranea (L.) Verdc.) Core Parental Lines Depends on the Root System Architecture during the Pre-Flowering Stage.

Characterizing the morphological variability in root system architecture (RSA) during the sensitive pre-flowering growth stage is important for crop performance. To assess this variation, eight bambara groundnut single genotypes derived from landraces of contrasting geographic origin were selected for root system architecture and rooting distribution studies. Plants were grown in a polyvinyl chloride (PVC) column system under controlled water and nutrient availability in a rainout shelter. Days to 50% plant emergence was characterized during the first two weeks after sowing, while taproot length (TRL), root length (RL), root length density (RLD), branching number (BN), branching density (BD) and intensity (BI), surface area (SA), root volume (RV), root diameter (RDia), root dry weight (RDW), shoot dry weight (SDW), and shoot height (SH) were determined at the end of the experiment, i.e., 35 days after emergence. Genotypes S19-3 and DipC1 sourced from drier regions of sub-Saharan Africa generally had longer taproots and greater root length distribution in deeper (60 to 90 cm) soil depths. In contrast, bambara groundnut genotypes from wetter regions (i.e., Gresik, Lunt, and IITA-686) in Southeast Asia and West Africa exhibited relatively shallow and highly branched root growth closer to the soil surface. Genotypes at the pre-flowering growth stage showed differential root foraging patterns and branching habits with two extremes, i.e., deep-cheap rooting in the genotypes sourced from dry regions and a shallow-costly rooting system in genotypes adapted to higher rainfall areas with shallow soils. We propose specific bambara groundnut genotype as donors in root trait driven breeding programs to improve water capture and use efficiency.