Root Initiation Research Articles

Adventitious root cultures of Decalepis salicifolia for the production of 2-hydroxy-4-methoxybenzaldehyde, a vanillin isomer flavor metabolite.

Decalepis salicifolia (Bedd. ex. Hook.f.) Venter is a potential natural source of the vanillin isomer, 2-hydroxy-4-methoxybenzaldehyde (2H4MB), an aromatic compound. However, the utilization of the plant is hindered especially due to its critically endangered status and the root-specific accumulation of the compound. The use of in vitro culture techniques offers a sustainable means for the production of valuable metabolites. In this study, an efficient system was established for the production of 2H4MB in the adventitious root cultures of D. salicifolia. Leaf explants of in vitro grown plants produced on an average 4.33 ± 2.07 number of roots with root initiation frequency of 95.69 ± 3.74% in woody plant medium supplemented with 0.5 mg/L α-naphthalene acetic acid (NAA) and 1.0 mg/L kinetin (Kn). The adventitious root biomass accumulation of 10.61 ± 0.89 g fresh weight (FW) was obtained in woody plant liquid media containing 0.5 mg/L NAA and 0.3 mg/L indole-3-butyric acid (IBA) in 60 days of inoculation. Field-grown plants of the same age produced 0.30 ± 0.02 g FW, which was 35-fold lower than the adventitious root culture. The total production of 2H4MB in the same growth period was 4.9-fold higher in adventitious root culture (139.54 μg) as compared to field-grown plants (28.62 μg). Furthermore, sucrose concentration of 2% was favorable for biomass accumulation, whereas 5% was favorable for 2H4MB production. On the other hand, media pH 5.0 was suitable for biomass production and pH 7.0 was best suited for accumulation of 2H4MB. The adventitious roots also showed stable production of biomass and 2H4MB over 2 years. The established adventitious root culture system is suitable for further large-scale production of 2H4MB for flavor and fragrance industrial applications. KEY POINTS: • Biomass accumulation was higher in adventitious root cultures than in field-grown plants. • Manipulation of sucrose concentration and media pH led to increased 2H4MB production. • Adventitious roots showed stable biomass and 2H4MB production over 2 years.

Microbial Biomass Carbon, Activity of Soil Enzymes, Nutrient Availability, Root Growth, and Total Biomass Production in Wheat Cultivars under Variable Irrigation and Nutrient Management

Intensive mono-cropping without a balanced supply of nutrients and declining water resources are degrading soil health, and as a consequence, agriculture production is becoming unsustainable and causing environmental degradation. The field experiment was conducted during Rabi season to assess the effect of an irrigation schedule, nutrient management, and wheat (Triticum aestivum L.) varieties on soil microbial biomass carbon (SMBC) and soil enzymes activities. Two nutrient levels, recommended rate of chemical fertilizer (RDF) and 50% RDF + 50% recommended dose of nitrogen (RDN) through farmyard manure (FYM) designated as Integrated Nutrient Sources (INS), and three irrigations levels, one irrigation at crown root initiation (CRI), two irrigations at CRI and flowering stages, and five irrigations at all main stages of the crop (CRI, tillering, jointing, flowering, and grain filling) were allocated to main-plots while four varieties of wheat, HD 2967, WR 544, HD 2987, and HD 2932, were allocated to sub-plots. The results revealed that SMBC and activities of dehydrogenase, alkaline phosphatase enzymes, and acid phosphatase were higher under restricted irrigation (irrigation at CRI stage) than other irrigation schedules. SMBC, dehydrogenase, acid phosphatase, and alkaline phosphatase activities were 73.0 µg g soil−1, 86.0 µg TPF g soil−1d−1, 39.6 µg PNP g soil−1 h1, and 81.8 µg PNP g−1 soil h−1, respectively, with the use of INS that was higher than RDF. Root weight and root volume followed a similar pattern. Applying single irrigation at CRI left behind the maximum available nitrogen (166.4 kg ha−1) in soil compared to other irrigation schedules and it was highest (149.31 kg ha−1) with the use of INS. Moreover, total organic carbon (TOC) was 0.44 and 0.43% higher with irrigation at CRI stages and the use of INS, respectively. The INS with single irrigation at the CRI stage is important to improve the root growth, SMBC dehydrogenase, alkaline phosphatase, and acid phosphatase enzyme activity in the wheat production system.

Broad leaf weed management in wheat by pre-emergence and pre-mix post-emergence combinations of herbicides under different irrigation schedule

A 2-years study was conducted to assess the impact of irrigation schedule and weed management practices on broad leaf weed (BLW) flora and wheat dry matter production. Experiments were conducted during Rabi season of 2017-18 to 2018-19 at CSAUAT, Kanpur under split-plot design with four replication having four irrigation regimes were assigned to main plots and eight weed management practices were allocated to sub plots. Irrigations at crown root initiation (CRI) and active tillering stage (I1) significantly reduce the density and weight of BLW with highest WCE and crop resistance index (CRI) over other irrigation regimes. However, irrigation at CRI+ jointing+ booting+ flowering+ milking stage (I4) recorded highest weed effectiveness (WE) and dry matter yield (CDMY) followed by irrigation at CRI + active tillering + booting + flowering stage (I3). All the weed management treatments significantly reduced the density and weight of BLW resulted maximum crop dry matter yield over weedy check. Among herbicidal treatments, lowest density, fresh and dry weight of BLW, WE and the highest WCE, CRI, WPI and CDMY was recorded with the application of broadway (carfentrazone ethyl 20% + sulfosulfuron 25%WG) 100 g ha-1 at 35 DAS and it was statistically at par with clodinafop- propagyl 15% + metsulfuron 1% 400 g ha-1 at 35 DAS.

Chlorophyll Content in Leaves of Wheat as Influenced by Inorganic, Organic and Integrated Sources of Nutrient Application

Field experiments were conducted during winter season of 2018-19 and 2019-20 with three sources of nutrient viz., inorganic, organics (FYM, VC and biofertilizers) and their integration as main treatments and five levels [S1-0 (0-0-0 kg NPK ha-1), S2-100% (120-60-40 kg NPK ha-1), S3-150% (180-90-60 kg NPK ha-1), S4-200% (240-120-80 kg NPK ha-1) and S5-Soil Test based (STV) NPK i.e. 149-176-33 kg ha-1 in split plot design with three replications. The chlorophyll content (‘a’, ‘b’ and total) in leaves and Soil Plant Analyzer Development (SPAD) value were recorded at crown root initiation (CRI), tillering, jointing and milking stage of wheat. The pooled data of findings revealed that the treatment with inorganic sources showed significant increase in the SPAD readings (9.62, 15.54, 23.77 and 29.83), chlorophyll ‘a’ (0.76, 0.83, 1.47 and 0.63 mg g-1 leaf tissue), ‘b’ (0.44, 0.78, 0.87 and 0.57 mg g-1 leaf tissue) and total (1.19, 1.64, 2.25 and 1.14 mg g-1 leaf tissue) chlorophyll content in leaves over organic source at all the growth stages.
 All the levels of nutrient were significantly increased the chlorophyll content and SPAD value over control at all the stages except chlorophyll ‘a’ at jointing and milking stage. However, amongst the levels 150% and 200% NPK were found significantly superior to 100% NPK for SPAD value (8.32 and 8.71 at CRI and 12.56 and 12.19 at tillering), chlorophyll ‘a’ (0.73 and 0.70 mg g-1 leaf tissue at CRI), chlorophyll ‘b’ (0.46 and 0.45 mg g-1 leaf tissue at CRI, 0.68 and 0.71 mg g-1 leaf tissue at tillering and 0.53 and 0.59 mg g-1 leaf tissue at milking), respectively.
 The interaction results suggested that the 200% NPK with inorganic and integrated sources significantly superior to 100% NPK for chlorophyll ‘a’ content at jointing and milking stage. The application of 150% and 200% NPK with inorganic source were found significantly higher over the same level of NPK with integrated source of nutrient for total chlorophyll content and SPAD value at all the growth stages except 150% NPK for total chlorophyll at jointing and milking stage and SPAD value at milking stage. The correlation between SPAD value and chlorophyll ’a’, ‘b’, total were found significantly and positively at all growth stages. Coefficient of determination values between SPAD and chlorophyll content showed linear relationship at all the growth stages.

Integration of Cell Growth and Asymmetric Division during Lateral Root Initiation in Arabidopsis thaliana

Lateral root formation determines to a large extent the ability of plants to forage their environment and thus their growth. In Arabidopsis thaliana and other angiosperms, lateral root initiation requires radial cell expansion and several rounds of anticlinal cell divisions that give rise to a central core of small cells, which express different markers than the larger surrounding cells. These small central cells then switch their plane of divisions to periclinal and give rise to seemingly morphologically similar daughter cells that have different identities and establish the different cell types of the new root. Although the execution of these anticlinal and periclinal divisions is tightly regulated and essential for the correct development of the lateral root, we know little about their geometrical features. Here, we generate a four-dimensional reconstruction of the first stages of lateral root formation and analyze the geometric features of the anticlinal and periclinal divisions. We identify that the periclinal divisions of the small central cells are morphologically dissimilar and asymmetric. We show that mother cell volume is different when looking at anticlinal vs. periclinal divisions and the repeated anticlinal divisions do not lead to reduction in cell volume, although cells are shorter. Finally, we show that cells undergoing a periclinal division are characterized by a strong cell expansion. Our results indicate that cells integrate growth and division to precisely partition their volume upon division during the first two stages of lateral root formation.

Influence of Organic Manures on Drought Stress at Different Growth Stages of Wheat

A pot experiment was conducted in the net house of the Agronomy department, Sher-e-Bangla Agricultural University, Dhaka during the period from November, 2018 to March, 2019 to evaluate the suitable organic source to mitigate the drought stress impact on wheat. The experiment comprised two factors viz. factor A: Three levels of organic manures, i) O0 = Control (Without organic manure), ii) O1 = Cowdung (10 t/ha), iii) O2 = Poultry litter (5 t/ha), and factor B: four levels of drought i) D0 = Control (without drought), ii) D1 = Crown root initiation stage (at 20-29 DAS), iii) D2 = Booting stage (at 45-54 DAS), iv) D3 = Anthesis stage (at 55-64 DAS). The experiment was laid out in a completely randomized design (factorial) with three replications. Organic manure showed positive impact on yield and cowdung (O1) gave the highest grain yield (4.06 g plant-1). This may be attributed to the highest number of effective tillers plant-1 (3.21), spike length (9.53 cm), spikelet spike-1 (17.31), grains spikelet-1 (2.31) and 1000-grain weight (44.61 g) of wheat in this treatment. In respect of drought imposition treatments, grain yield was found higher in control treatment (without imposition of drought) which was statistically similar with drought imposition at booting stage treatment (D2). These two treatments also showed highest number of effective tillers plant-1, spikelets spike-1, grains spike-1 and 1000-grain weight. Regarding the interaction of organic manure and drought, cowdung without drought imposition (O1D0) and cowdung with drought imposition at booting stage (O1D2) were highest yielder among the other interactions which was attributed to higher 1000-seed weight, number of effective tillers plant-1, spikelets spike-1 and grains spike-1. Results revealed that application of organic manure could reduce the impact of drought on wheat irrespective of growth stages. However, application of cowdung (10 t ha-1) was found more effective to combat drought impact at booting stage of wheat compared to other growth stages.
 Bangladesh Agron. J. 2020, 23(2): 81-86

Elicitation of industrially promising vanillin type aromatic compound 2-hydroxy 4-methoxy benzaldehyde (MBAlD) yield in the in-vitro raised medicinal crop Hemidesmus indicus (L) R. Br. by methyl jasmonate and salicylic acid

Growth promoting and secondary metabolite enhancing roles of the elicitors, methyl jasmonate (MeJA) and salicylic acid (SA) were investigated in the popular medicinal crop Hemidesmus indicus (L) R. Br. or Indian Sarsaparilla grown in-vitro. In-planta elicitor treatment (MeJA; 25, 50, and 75 μM and SA; 0.75, 1.5, and 2 mg/mL) induced growth of nodular meristemoids, promoted overall growth and demonstrated enhanced bioactivity and accumulation of root specific alkaloid 2-hydroxy 4-methoxy benzaldehyde (MBAld). A fast and effective micropropagation protocol including both direct and indirect organogenesis and regeneration was standardized for H. indicus (HI-KOL). Murashige and Skoog (MS) media fortified with 6-benzylaminopurine (BAP) (1.5 mg/L) produced the highest (6.7) number of shoots/ explant and average shoot length was 11.7 cm. It was followed by thiodiazuron (TDZ) (1.5 mg/L) (avg. shoot/explant 6.5 and avg. shoot length 11.1 cm). The percentage of emergence of shoot initials from the light green-compact base callus was highest (100%) in MS media supplemented with TDZ (2 mg/L) followed by indole-3-butyric acid (IBA) or indole-3-acetic acid (IAA) (0.50 mg/L). Highest average callus diameter (3.7 cm) was noted in MS media fortified with TDZ (2.0 mg/L) + IBA (0.50 mg/L). For root initiation, IBA (1.5 mg/L) fortified MS medium demonstrated the best result (average root length 9.1 cm). Best responsive in-vitro raised plant materials also demonstrated significant total phenolics, flavonoid, tannin, and photosynthetic pigment contents when compared with other samples and in-vitro grown plantlets. Competitive antioxidant activity 1,1-diphenyl2-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays, activity of antioxidant enzymes [superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT)], and elicitor stimulated pancreatic lipase inhibitory activities were also noted. In addition, a rapid, validated, and sensitive densitometric protocol for high performance thin layer chromatography (HPTLC) quantification of MBAld was also standardized and it was noted that both MeJA and SA stimulated accumulation of MBAld in in-vitro samples but the effect was more prominent in MeJA treated plant derived root extracts with 75 μM MeJA treatment produced 3.41 ± 0.8 mg/g MBAld which was higher than the mother plant (MP) (3.30 ± 0.2 mg/g). HPTLC analyses also revealed phytochemical fidelity among the MPs and the treated and non-treated micropropagated plant samples.

The mechanism of auxin transport in lateral root spacing

The mechanism of auxin transport in lateral root spacing

Spectral Signature-Based Water Stress Characterization and Prediction of Wheat Yield under Varied Irrigation and Plant Bio-regulator Management Practices

Canopy reflectance based spectral indices help in effective irrigation scheduling of wheat for optimization of yield in water-scarce regions. A field experiment for two consecutive years (2013 to 2015) was conducted to evaluate the responses of wheat crop to exogenous application of plant bio-regulators (PBRs) in the water-scarce Deccan region of India (Baramati, Pune, Maharashtra). We predicted grain and biomass yields of wheat using water stress-sensitive spectral indices under varied water regimes. The water regimes were seven levels of irrigation water (equaling to 1.00, 0.85, 0.70, 0.55, 0.40, 0.25 and 0.10 times of cumulative open pan evaporation, CPE) and applied using a line-source sprinkler system). There were five PBRs, viz. thiourea, salicylic acid, potassium nitrate, gibberellin and ortho−silicic, with concentration 10 mM, 10 μM, 15 g L−1, 25 ppm and 8 ppm, respectively, applied at various growth stages, namely crown root initiation, flag leaf and seed milking stages. Water stress indices were computed from spectral reflectance pattern recorded at different crop growth stages using ASD FieldSpec-4 Spectroradiometer (350–2500 nm). The PBRs significantly influenced the canopy reflectance pattern and maintained superior values of water stress indices over the control (without PBRs) by stabilizing leaf pigments and water contents, controlling the stomatal opening and better water use. Among the five PBRs, thiourea and salicylic acid mitigated water stress better and improved overall grain yield (4.6–17.5%) and total biomass (3.6–15.3%). There was no significant (p < 0.05) variation in both yields (grains and biomass) up to IW: CPE 0.70, indicating that irrigation scheduling at 0.70 IW: CPE could be a better option rather than full irrigation in water-scarce areas. At flowering and milking stages, all spectral indices were correlated significantly with the wheat yields. Thus, these stages could be considered as more water-sensitive stages during entire wheat growth period. Regression models based on WI and NWI-2 accounted for 92% and 78% variation in the observed yields for grain and biomass, respectively, with minimum root-mean square error. Hence, to predict the grain and biomass yields of wheat, regression models based on WI and NWI-2 at milking stage can be used successfully.

Slow recovery from soil disturbance increases susceptibility of high elevation forests to landslides

Natural hazards such as shallow landslides are common phenomena that disturb soil and damage forests. Quantifying the recovery of forest vegetation after a hazard is important for determining the window of susceptibility to new disturbance events, especially at high elevations, where extreme weather events are frequent and the growing season is short. Plant roots can reduce the size of this window on unstable hillslopes, by adding mechanical reinforcement (cr) to soil and increasing its matric suction, termed here as hydrological reinforcement (ch). These data are used in landslide models to calculate the Factor of Safety (FoS) of a hillslope. We calculated temporal variations in cr and ch in naturally regenerated mixed, montane forests in the French Alps. In these closed-canopy forests, open-canopy gaps were present, with understory vegetation comprising herbs, forbs and shrubs. At three altitudes (1400, 1700 and 2000 m), we dug small trenches as proxies for shallow landslide events and calculated cr before soil disturbance in both open gaps and closed forests. Then, using monthly tree root initiation and mortality data measured in rhizotrons, we calculated monthly cr for four years after the disturbance. To compare results with cr, ch was estimated using matric suction data that were measured in trenches at 1400 m for >1 year. Temporal FoS was then calculated using an infinite slope stability model.Results showed that finer, short-lived roots contributed little to soil reinforcement compared to thicker, long-lived roots. After disturbance, mean cr (over the entire soil profile) never fully recovered to the initial value at any site, although >90% recovery was observed in open gaps at 1400 m. Mean cr was slow to recover in closed forests, especially at 2000 m, where only 19% recovery occurred after 41 months. The ch in closed forests was considerable during the summer months, but marked increases in soil water moisture resulted in lower FoS, especially during December to April, when soil was near saturation. As cr changed little throughout the year, it was a more reliable contributor to slope stability. Our results show therefore, that particular attention should be paid to high elevation forests after a disturbance. Also, during the process of recovery, the highly variable soil water dynamics in closed forest can result in seasonal hotspots of vulnerability. Therefore, when tree transpiration is low, our results highlight a need for careful monitoring on steep or unstable slopes, especially in disturbed closed-canopy forests.

Effect of media concentration and growth hormones on shoot regeneration and in vitro rooting of sugarcane varieties (Saccharum spp. )

The protocol for plantlet induction and regeneration through in vitro culture was standardized for the sugarcane variety Co 06022 with Co 86032. Genotype specific media combinations for establishment and rooting efficiency was identified and standardized. Multiple shoot regeneration was observed at different frequencies, using different concentration and growth regulator combination. In vitro propagation of Saccharum offers opportunities for increasing plant material for cultivation. Apical meristems were cultured on modified MS medium containing different concentrations of auxins. In Co 06022, the most effective concentration was combination of ½ MS medium supplemented with IBA (2.0 mg/l) which induced an average of 3.00±0.14 number of shoots per microshoot with 10.77±0.42 cm shoot length. Among the auxins used, NAA showed better response than IBA for profuse rooting in Co 06022. The number of roots formed was maximum (14.80±0.09) in MS with NAA (2mg/l) which had taken 10 days for root initiation with the root length of 6.45±0.07 cm. However, in Co 86032, the best performance was observed on ½ MS medium supplemented with IBA (2.0 mg/l) with more number of shoots (2.00 ± 0.19) and average shoot length of 12.30± 0.44 cm. Best rooting was observed in ½ MS medium supplemented with NAA (2.0 mg/l) and maximum number of roots were 11.60±0.12 which has taken 8 days for initiation of root primordia with average root length of 1.16±0.12 cm. Thus, it can be deduced that this protocol can be used successfully for in vitro rooting and acclimatization of these genotypes.

Dynamic cytokinin signalling landscapes during lateral root formation in Arabidopsis

By forming lateral roots, plants expand their root systems to improve anchorage and absorb more water and nutrients from the soil. Each phase of this developmental process in Arabidopsis is tightly regulated by dynamic and continuous signalling of the phytohormones cytokinin and auxin. While the roles of auxin in lateral root organogenesis and spatial accommodation by overlying cell layers have been well studied, insights on the importance of cytokinin is still somewhat limited. Cytokinin is a negative regulator of lateral root formation with versatile modes of action being activated at different root developmental zones. Here, we review the latest progress made towards our understanding of these spatially separated mechanisms of cytokinin-mediated signalling that shape lateral root initiation, outgrowth and emergence and highlight some of the enticing open questions.

Effect of seed hardening and irrigation on economics of wheat (Triticum aestivum L.) cultivation

The experiment was conducted to study the performance of various seed hardening chemicals in late sown variety of wheat (Triticum aestivum L.) at the Crop Research Farm, Department of Agronomy, Naini Agricultural Institute, Sam Higginbottom University of Agriculture, Technology and Sciences (SHUATS), Prayagraj (U.P.) The experiment comprise of 13 treatment within 3 replication laid out in a randomized block design to evaluate the performance of various seed hardening chemicals viz. Distilled water, KNO3 at 1000mg per liter, PEG at 15% and GA3 at 450 mg/ liter. The highest straw yield (45.15t), grain yield (3.52t) and harvest index (7.27) was observed in the treatment PEG at 15%+Three Irrigations at crown root initiation, jointing and anthesis stage. The highest cost of cultivation (₹50894.00), gross return (₹59678.00), net return (₹36801.00) and B:C ratio (1.723) is also observed inT9, respectively.

Elimination of phytoplasmas in brinjal by meristem-tip culture incombination with thermotherapy

The main aim of the study was to eliminate the phytoplasmas in brinjal using meristem-tip culture in combination with thermotherapy. Brinjal shoot tips were taken from field grown plants and subjected to different temperature/time treatments followed by meristem tip excision and culture in a callus inducing medium. The 45°C for 2 minutes showed the minimum number of days for callus induction and the maximum survival percentage of explants. MS medium with BAP 1 mgl−1 and kinetin 1 mgl−1 recorded the maximum shoot initiation percentage at all temperature treatments. The MS medium with BAP 2 mgl−1, kinetin 1 mgl−1 and NAA 0.5 mgl−1 recorded minimum number of days for multiple shoot formation and produced more shoots per callus clump. For root formation, half concentration in MS medium supplemented with IBA 0.5 mgl−1 and IAA 0.5 mgl−1 recorded lesser number of days for root initiation and produced more roots per shoot. Effective regeneration was recorded at 45°C for 2 minutes. To confirm the elimination of phytoplasmas, DNA was extracted from these plants and from little leaf diseased brinjal plants. The molecular detection was done through PCR and the phytoplasma infected plant sample produced the expected length amplification products while no amplification was observed in the in vitro grown plants.

Photosynthesis product allocation and yield in sweetpotato with different irrigation levels at mid-season

Soil water deficit is one of the important factors affecting the source–sink balance of sweetpotato at mid-season growth (storage root initiation period). However, water regulation at mid-season sweetpotato growth is often ignored. In this study, field trials were conducted to diagnose leaves in the middle of sweetpotato growth, and then three mid-season irrigation levels (CK: 0 m3/hm2; W1: 150 m3/hm2; W2: 300 m3/hm2) were established. The effects of different irrigation levels on photosynthetic physiological indexes, 13C transfer allocation, and yield of sweetpotato were studied. The results revealed that mid-season irrigation significantly increased the relative moisture content of sweetpotato leaves, maximum photochemical efficiency (Fv/Fm), and net photosynthetic rate (Pn) (P < 0.05), which effectively alleviated the effects of soil water deficit. The Pn values with irrigation treatments W1 and W2 were significantly higher than those with control (CK) treatment in all three study periods. Among these, the W2 treatment had the highest Pn at 70 d, an increase of 113.4% compared with CK in 2019 test, and W1 had the highest Pn at 110 d and 150 d (P < 0.05). The trend of stomatal conductance (Gs) was basically consistent with Pn. The transpiration rate (Tr) of W2 was the highest at 70 d, an increase of 59.8–69.7% compared with CK, but the Tr of W1 was the highest at 110 d and 150 d. The 13C total accumulation in the W1 treatment was the highest at 70 d, 110 d, and 150 d, when it was 21.9%, 20.4%, and 33.1% higher than that of the W2 treatment in 2019 test (P < 0.05), respectively. The 13C allocation rate of storage roots treated with W1 was the highest in all periods, reaching as high as 73.1–76.1% at 150 d (P < 0.05). At 70 d, the 13C allocation rate of fiber roots and stems was highest in the CK treatment, whereas the 13C allocation rate of leaves was highest in W2 (P < 0.05). At 110 d and 150 d, the 13C allocation rate of stems and leaves in CK was the highest (P < 0.05). The biomass of W2 was the highest at 70 d, but the root-to-shoot ratio and the dry weight of root became gradually lower than those of the CK and W1 treatments at the late season, when they were reduced by 28.4% and 32.2% compared to W1 at 150 d in 2019 test (P < 0.05). The yield of W1 was increased significantly by 33.3–34.9% compared with CK (P < 0.05), but W2 only had an increased production of 14.5–20.7% (P < 0.05) compared to CK (P < 0.05). The irrigation water utilization efficiency of W2 was 59.4–61.8% and 39.1–43.5% lower than those of the CK and W1 treatments (P < 0.05), respectively. Together, these results validate the field sweetpotato mid-season water management model, which is of great significance for guiding actual production of sweetpotato and increasing the potential of sweetpotato.

EFFECT OF DIFFERENT TYPES AND CONCENTRATION OF ROOTING HORMONES ON Momordica cochinensis (GAC FRUIT) ROOT VINE CUTTINGS

Momordica cochinchinensis (Gac fruit) grows as perennial climbers and dioecious plants, where it can be cultivated from seeds, root tubers, and root vine cuttings. Rooted vine cuttings are more reliable than seed propagation, which can be affected by dormancy and delay production. The application of auxin group of hormones such as Indole acetic acid (IAA), Indole-3- butyric acid (IBA), and Naphthaleneacetic acid (NAA) in certain concentrations shown good results in inducing root initiation faster and effective. However, experimental data and information on the plant growth hormone application on M. cochinchinensis vine cuttings propagation are not very extensive, especially in Malaysia. Thus, the objective of this study was to determine the effect of different concentrations of IAA, IBA, and NAA on M. cochinchinensis vine cutting propagation. The design of the experiment is a randomized complete block design in a factorial experiment, with five replications. The treatments comprised three types of plant growth hormone, IAA, IBA, and NAA with 0, 500, 1000, and 3000 ppm concentrations. Data recorded were surviving rate or percentage of rooting, root numbers per rooted cutting, means of root length, length of longest root, total root length per rooted cuttings, sprouting percentage, and sprouting length. The vine cutting treated with IBA and NAA 1000 ppm has shown a considerably positive effect in root formation and sprouting.

Adaptive roots of mangrove Avicennia marina: Structure and gene expressions analyses of pneumatophores

The Avicennia marina is a mangrove species widely distributed throughout the tropical and subtropical intertidal wetlands. To adapt to adverse tidal waves and hypoxia environments, A. marina has evolved a sophisticated root system to better secure itself on the muddy soil with downward-grown anchor roots and upward-grown aerial roots, called pneumatophores. However, the process behind the development of a negative-gravitropic pneumatophore is not understood. Paraffin sections reveal anatomical differences among the shoots, anchor roots, and gas exchanging pneumatophores, clearly reflecting their functional diversions. The pneumatophore, in particular, contains abundant aerenchyma tissues and a thin cap structure at the tip. Transcriptomic analyses of both anchor roots and pneumatophores were performed to elucidate gene expression dynamics during the formation of pneumatophores. The results show that the plant hormone auxin regulates multiple different root initiations. The auxin related gene IAA19 plays a key role in pneumatophore development while the interaction of ethylene and abscisic acid is important for aerenchyma formation. Moreover, the molecular mechanisms behind pneumatophore anti-gravitropic growth may be regulated by the reduced strength of the statolith formation signaling pathway. These results shed light on the mechanistic understanding of pneumatophore formation in mangrove plants.

Ammonium fertilization increases pearl millet yield by promoting early root growth, higher tillering, and water use during grain filling in a low P Sahelian soil

AbstractBackground: Adaptation of pearl millet [Pennisetum glaucum (L.) R. Br.] to low soil phosphorus (P) at early seedling stages and efficient P fertilizer application are crucial for its survival in the West African Sahel. While addition of to P in the microdose technique has been reported to stimulate early growth of pearl millet, there is little information regarding root length (RL) at different timings.Aims: Our study aimed at assessing the effects of added and to P on (1) pearl millet agronomic traits such as root and shoot growth and (2) the water use dynamics during the cropping cycle.Methods: Twenty‐four “RhizoTubes” filled with P‐deficient soil were used to grow pearl millet under three treatments: (T1) placed P addition alone at 0.4 g per seed hole, Pplaced, (T2) Pplaced + , and (T3) Pplaced + . At 2, 3, 4, and 5 weeks after sowing (WAS) we took non‐destructive measurements of RL. Water use (transpiration) was measured from 3.5 to 9 WAS.Results: At early growth, roots in the topsoil of T2 were longer than T3 and T1 roots (at 4 WAS: 129.3 cm for T2, 87.5 cm for T3, and 93.3 cm for T1, p &lt; 0.05). Total RL at 2 WAS correlated positively with seedling height and final grain yield. Fertilization with reduced the time to flowering and increased the number of tillers and grain yield, whereas addition of increased vegetative dry matter at harvest and water use efficiency.Conclusions: Our findings suggest that fertilization with plays a critical root stimulating role at early growth stages, seemingly by increasing lateral root initiation, which carries through to a larger water use during grain filling and higher grain yield.

Viability and Vigor of Bacaba Seed (Oenocarpus bacaba) in Different Substrates

The Bacaba (Oenocarpus bacaba) belongs to the Arecaceae family, is a palm tree native to the Amazon, in which it is distributed throughout the Amazon basin, mainly in the regions of Pará, Tocantins, Acre, and in southern Maranhão, having as habitat the high virgin forest. The production of quality seedlings depends on several factors, and the composition of substrates is a major factor, because seed germination, root initiation, and rooting are directly linked to the chemical, physical and biological characteristics of the substrate. The experiment was carried out at the Federal Institute of Education - IFTO, Sciences, and Technology of Tocantins, in the city of Gurupi - TO, between September 5, 2018, and December 30, 2018. For the realization of the same, Bacaba seeds (Oenocarpus bacaba) were used, which were purchased at the street fair in the municipality of Gurupi - TO. Root and shoot length, number of leaves, root and shoot dry mass, first emergency count and seedling emergence were evaluated. The substrates: Washed Sand, Commercial Substrate, Pinus Bark + Sawdust Powder + Commercial Substrate, and Worm Humus + Coconut Shell + Commercial Substrate + Sawdust Powder provided the highest values of viability and vigor in Bacaba seeds.

A Micropropagation Protocol for the Endangered Medicinal Tree Prunus africana (Hook f.) Kalkman: Genetic Fidelity and Physiological Parameter Assessment.

Prunus africana is an endangered medicinal plant and hence new propagation methods are urgently required to increase its populations. Unfortunately, propagation through seeds is challenging due to its long flowering cycle and recalcitrant seeds. We developed a protocol for micropropagation using nodal segment explants. A woody plant medium supplemented with vitamins, 15 g L−1 sucrose, and 1.0 mg L−1 6-benzylaminopurine (BAP) supported the optimum rate (100%) of axillary shoot initiation. Supplementation with 15 g L−1 sucrose and 1.5 mg L−1 indole-3-acetic acid (IAA) provided the optimum rate (75%) of root initiation. Rooted plantlets were successfully planted in sterilized horticultural soil containing perlite (2:1 v/v) and the survival rate was 98% following acclimatization. The photosynthetic rate assessed using FlourPen FP110 series showed that the ratio of variable fluorescence to maximum fluorescence mean value for in vitro regenerated P. africana (0.830 ± 0.0008) was similar to that of the maternal P. africana plant (0.825 ± 0.005), indicating similarity in their photosynthetic performance; a pivotal process for growth and development. The Fourier transform near-IR (FT-NIR) spectrometer analysis of the in vitro regenerated and the maternal P. africana plant samples exhibited homogeneity in the absorbance peaks at 8,273, 6,344, and 4,938–4,500 cm−1 associated with lipids, starch, and proteins. The genetic fidelity of regenerated plants was confirmed using the randomly amplified polymorphic DNA (RAPD) technique. Our protocol is suitable for use in large-scale P. africana to meet the increasing demands for it in the global market.