Assessment of the Effect of Cutting Length on Sprout and Growth of Pterocarpus santalinoides L’hérit. Ex Dc

Aims: This study evaluated the effect of cutting lengths on sprouts and seedling growth of P. santalinoides. Study Design: The experiment was laid out in a Completely Randomised Design (CRD). Place and Duration of Study: The study was carried out at the Department of Forestry and Wildlife Management Nursery, University of Port Harcourt, Rivers State, Nigeria, between April 2019 and March 2020. Methodology: Ten (10) cuttings per cutting length were planted in a polybag filled with forest topsoil. The treatments are; 13, 20, 25 and 33 cm cutting lengths. Five seedlings per treatment were randomly selected and dried for biomass. Emergence of sprouts, number of leaves and branches, survival rate, number of cuttings that sprouted, sprout length, root length and biomass were determined and subjected to analysis of variance. Results: Sprouts emergence occurred earliest in 25 cm cuttings (7 days) and latest in 13 and 20 cm cuttings (12 days). There were significant differences (P ≤ 0.05) in leaf number at month 1, number of branches at months 1, 3, 5 and 9, cutting length at month 2 and root to shoot ratio and non-significant differences (P > 0.05) in leaf number at months 3,5,7,9 and 11, number of branches at months 7 and 11, number of sprouts, cutting length at month 12, root length, shoot biomass, root biomass and total fresh and dry weight. Twenty five (25) cm long cutting enhanced sprout parameters while 33 cm long cutting enhanced root parameters. Conclusion: The result showed that 25 and 33 cm long cuttings are most suitable cutting lengths and are therefore recommended for growth of the species.

In vitro assessment of elevated soil iron on germinability and germination characteristics of Sorghum bicolor (L.) Moench after chemo-priming

The commercial importance of Sorghum (Sorghum bicolor (L.) Moench) has attracted breeders to increase its seed yield using various breeding approach. Adverse soil factors however hampered progress made in crop development, especially micronutrient toxicity. Plant growth stimulators (PGS) have a significant role in enhancing growth parameters in Sorghum. In the present study, seeds were primed in 50, 150, and 250 ppm of each of gibberellic acid, indole acetic acid, and ascorbic acid respectively for 1 hr before sowing in Petri dishesmoistened with 10 ml of the iron-rich solution obtained as filtrate from a mix of distilled water and ferruginous soil (1:1 v/w). Results showed that although germination percentage in ferruginous medium was significantly reduced, there was enhancement in germination percentagewhen the seeds were primed in gibberellic acid (GA). Germinability in the iron-rich medium was 31.2 hrs; this was significantly reduced to 19.6 to 21.1hrs when these seeds were primed with growth stimulators.Although, shoot length was significantly reduced in plants exposed to ferruginous solutions, the root parameters were however enhanced. They were no significant changes in the total number of root branches regardless of ferrugenic status or use of growth stimulating agents. The utilization of growth stimulators as priming agents is called for to reduce stress impacts imposed by ferruginous soils during germination.

Seed Source Effects on Germination, Growth, and Yield of Carrots Under Natural Farming

Natural farming is a type of low-input sustainable agricultural system that is characterized by the avoidance of the use of any animal materials. Production of self-produced seeds by farmers is recommended under natural farming environments, with an expectation of improved crop growth and yield. However, there have been no scientific studies that investigated the performance of self-produced seeds under natural farming. This study investigated the germination rate, growth, and yield of carrots (Daucus carota L.) from different seed sources under natural farming. The main experimental factor was the cultivation method: CT – control; CF – conventional farming; NF1 – natural farming with tillage and compost input; and NF2 – natural farming without tillage and compost, and the subfactor was the seed source: OPN – open-pollinated seeds self-produced under natural farming; OPC – open-pollinated seeds produced under conventional farming; and HB – hybrid seeds. The germination rate of OPN seeds was higher than that of other seeds. In addition, root fresh weight and other root parameters of OPN were as high as for HB seeds. This suggests that using self-produced seeds by farmers improves crop performance in a natural farming system.

Effect of Phytohormones on rooting behaviour in air layers of Phoebe cooperiana, an economically important tree species of Arunachal Pradesh, India

This study reports the response of air layers of Phoebe cooperiana (Common name: Tapil) to different concentrations of rooting hormones in mid hills of Arunachal Pradesh. Ten trees between the ages of 7 and 10 were selected at Boleng village of Siang district, Arunachal Pradesh, India for the experiment. Eight treatments comprising of IBA and NAA at concentrations of 1000ppm, 2000ppm and 3000ppm each, Rootex hormone for semi-hardwood and control were applied to a total of 240 layers during April 2020. After 60 days, rooting percentage, mean number of roots and length of the longest root were recorded. Significant variation (p<0.05) among treatments was observed for all root parameters. Among treatments, the highest rooting percentage and mean a number of roots were obtained in layers treated with NAA 3000ppm (80% and 21.33 respectively). The length of the longest root was the highest in layers treated with NBA 2000ppm (4.23cm). The highest survival percentage of layers two months after transplanting was observed in those treated with NAA 3000ppm (54.16%) and the least in control (23.07%). The technique offers an easy and cheap method of propagation for farmers as well as for government and private agencies to enhance seedling production of the species.

Elevated carbon dioxide and temperature effects on rooting behaviour of grape cuttings

An experiment was laid out to study the impact of eCO2 (550ppm), eT (+3ºC) and their interaction (eCO2+eT) on rooting behaviour of cuttings of three grape varieties- Thompson Seedless, Bangalore Blue, and Dogridge in FATE and OTC facilities. Observations were recorded at 50 and 80 days after planting (DAP) and root growth data was recorded and analysed using WinRHIZO root scanner and its software. Analysis revealed that, among the selected grape varieties, Thompson Seedless cuttings has shown highest number of roots, root volume and dry biomass under eCO2 and eCO2+ eT conditions, while total root length and root length density were highest with Bangalore Blue. Under eT condition, Bangalore Blue showed highest number of roots, total root length and root length density, while root volume and dry biomass was highest with Thompson Seedless. The per se values of root parameters under all conditions and their response to eCO2 was lowest with Dogridge. Though eT condition reduced all the root parameters, their performance improved under eCO2+ eT indicating the presence of higher concentration of CO2 reduced the ill effects of high temperature. Overall, eCO2 and eCO2+eT conditions improved root parameters of grape varieties, while eT reduced them as compared to their performance under ambient condition and varietal variation is significant.

Growth, Physiological, and Photosynthetic Responses of Xanthoceras sorbifolium Bunge Seedlings Under Various Degrees of Salinity

Xanthoceras sorbifolium Bunge is priced for its medical and energetic values. The species also plays a key role in stabilizing ecologically fragile areas exposed to excess soil salinity. In this study, the effects of salinity on the growth, physiological, and photosynthetic parameters of X. sorbifolium Bunge were investigated. The X. sorbifolium seedlings were subjected to five salt treatments: 0 (control, CK), 70, 140, 210, and 280 mM of sodium chloride (NaCl) solutions. NaCl caused a decrease in plant height, specific leaf area, biomass, and root parameters. Leaf wilting and shedding and changes in root morphology, such as root length, root surface area, and root tips were observed. This study found that X. sorbifolium is tolerant to high salinity. Compared with the CK group, even if the concentration of NaCl was higher than 210 mM, the increase of the relative conductivity was also slow, while intercellular CO2 concentration had a similar trend. Moreover, NaCl stress caused an increase in the malondialdehyde (MDA), soluble proteins, and proline. Among the enzymes in the plant, the catalase (CAT) activity increases first and decreased with the increase in the intensity of NaCl stress, but the salt treatment had no significant effect on superoxide dismutase (SOD) activity. The peroxidase (POD) showed an increasing trend under salt stress. It was found that the photosynthesis of X. sorbifolium was notably impacted by saline stress. NaCl toxicity induced a noticeable influence on leaf net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO2 concentration (Ci), transpiration rate (E), and water use efficiency (Wue). As salt concentration increased, the content of chlorophyll decreased. It can be found that a low concentration of NaCl induced the increase of photosynthetic capacity but a high-intensity exposure to stress resulted in the reduction of photosynthetic efficiency and SOD activity, which had a positive correlation. In summary, salt-induced ionic stress primarily controlled root morphology, osmotic adjustment, and enzyme activities of salt-treated X. sorbifolium leaves, whereas the low salt load could, in fact, promote the growth of roots.

Contrasting ability of deep and shallow rooting rice genotypes to grow through plough pans containing simulated biopores and cracks

Aims Cracks and biopores in compacted soil such as plough pans could aid deep rooting, mitigating constraints to seasonal upland use of paddy fields for rice production. This research investigated how soil macropores through a simulated plough pan affects root growth of contrasting deep and shallow rooting rice genotypes. Methods Deep rooting Black Gora and shallow rooting IR64 rice varieties were grown in packed cores of unsaturated soil in a controlled greenhouse. Simulated biopores and cracks (macropores) were inserted through the plough pan to form treatments with no macropores, biopores, cracks, and combined cracks and biopores. Different root parameters such as root length density (RLD), root volume, root diameter, number of root tips and branches were measured. The number of roots was calculated manually, including the number of roots growing through macropores in the plough pan layer. Results Plough pans with macropores had 25–32% more roots than with no macropores. RLD was 55% greater in the plough pan layer if cracks were present compared to biopores. Conversely, RLD was 26% less in subsoil if the plough pan had cracks compared to biopores. Different root parameters were greatly influenced by the presence of macropores in the plough pan, and deep-rooted Black Gora produced 81% greater RLD, 30% more root numbers and 103% more branching than the shallow rooted rice genotype IR64 within the plough pan layer. Conclusions Macropores greatly improve rice root growth through plough pans for a deep rooting but not a shallow rooting rice variety. Whereas cracks produce a greater number of roots in the plough pan, biopores result in greater root branching and root numbers deeper in subsoil.

Enhanced Iron Uptake in Plants by Volatile Emissions of Rahnella aquatilis JZ-GX1

Iron deficiency in soil has crucially restricted agricultural and forestry production. Volatile organic compounds (VOCs) produced by beneficial microorganisms have been proven to play an important role in inducing abiotic stress tolerance in plants. We investigated the effects of VOCs released by the rhizobacterium Rahnella aquatilis JZ-GX1 on the growth and root parameters of Arabidopsis thaliana under iron deficiency. The effect of the rhizobacterial VOCs on the gene expression in iron uptake and hormone signaling pathways were detected by RT-qPCR. Finally, the VOCs of the JZ-GX1 strain that could promote plant growth under iron deficiency stress were screened. The results showed that the JZ-GX1 strain could induce A. thaliana tolerance to iron deficiency stress by promoting the development of lateral roots and root hairs and increasing the activities of H+ ATPase and Fe3+ reductase. In addition, the AHA2, FRO2, and IRT1 genes of A. thaliana exposed to JZ-GX1-emitted VOCs were upregulated 25-, 1. 81-, and 1.35-fold, respectively, and expression of the abscisic acid (ABA) synthesis gene NCED3 was upregulated on both the 3rd and 5th days. Organic compounds were analyzed in the headspace of JZ-GX1 cultures, 2-undecanone and 3-methyl-1-butanol were found to promote Medicago sativa and A. thaliana growth under iron-limited conditions. These results demonstrated that the VOCs of R. aquatilis JZ-GX1 have good potential in promoting iron absorption in plants.

Bayesian inference of root architectural model parameters from synthetic field data

Background and aims Characterizing root system architectures of field-grown crops is challenging as root systems are hidden in the soil. We investigate the possibility of estimating root architecture model parameters from soil core data in a Bayesian framework. Methods In a synthetic experiment, we simulated wheat root systems in a virtual field plot with the stochastic CRootBox model. We virtually sampled soil cores from this plot to create synthetic measurement data. We used the Markov chain Monte Carlo (MCMC) DREAM(ZS) sampler to estimate the most sensitive root system architecture parameters. To deal with the CRootBox model stochasticity and limited computational resources, we essentially added a stochastic component to the likelihood function, thereby turning the MCMC sampling into a form of approximate Bayesian computation (ABC). Results A few zero-order root parameters: maximum length, elongation rate, insertion angles, and numbers of zero-order roots, with narrow posterior distributions centered around true parameter values were identifiable from soil core data. Yet other zero-order and higher-order root parameters were not identifiable showing a sizeable posterior uncertainty. Conclusions Bayesian inference of root architecture parameters from root density profiles is an effective method to extract information about sensitive parameters hidden in these profiles. Equally important, this method also identifies which information about root architecture is lost when root architecture is aggregated in root density profiles.