Larger Root Length Research Articles

Root traits of soybeans exposed to polyethylene films, polypropylene fragments, and biosolids

Biosolid use imports microplastics into the rhizosphere where they may interfere with root-soil-microbial interactions and cause morphological adaptations in crop root systems. Few studies have examined the response of crop roots to microplastics at documented soil concentrations, and many studies collect root traits using destructive techniques. Hence, there is little information on when and how microplastics effect the physical structure of root systems. Using the rhizobox method, soybeans (Glycine max) were grown in soil amended with biosolid microplastic mimics (polyethylene film or polypropylene fragments at 2,000 and 15,000 particles/kg dry soil) or biosolids and imaged weekly until maturity (11 weeks) using a custom scanner system. Plant biomass increased in the polyethylene treatments and decreased in the high concentration polypropylene treatment. Relative to the Control, polyethylene treatments had larger root length, reduced root diameters, reached maturity faster, had deeper root systems, and had a greater number of lateral roots. In contrast, polypropylene treatments had a mixed response, with high concentrations eliciting a lower root length, fewer laterals, and a more vertical root orientation. Segmented linear regression revealed that root growth in the Control and Biosolid treatments continued through the course of the experiment, while the microplastic treatments reached maturity up to two weeks earlier. Imagery revealed that microplastics elicited deeper rooting depth within the first week and differences in all root traits were evident by the development of the first trifoliate leaflets. Microplastic effects on root traits at early life stages suggest soil physiological drivers, while increased branching frequency and lower lateral elongation are suggestive of changes in soil nitrogen availability. The minimal difference in root traits in the biosolid treatment may be attributable to differences in microplastic properties or counteractive effects by other biosolid constituents.

Использование регулятора роста растений янтарной кислоты при укоренении одревесневших черенков сортов и форм груши

As a result of the conducted research, it was found that when treated with succinic acid, the plant growth regulator, the greatest rooting result was observed in the varieties of pear Svetlyanka (k), Memory Yakovleva, Yakovlevskaya, Chudelnitsa. This indicator ranged from 75.1 to 77.8%. Without the use of a plant growth regulator (from 60.0 to 65.7%), the pear varieties Svetlyanka (k), Memory Yakovleva, Yakovlevskaya, Chudelnitsa had the greatest rootability. According to Table 2, the highest height of increments (from 15.0 to 15.6 cm) when treated with plant growth regulator succinic acid were characterized by pear varieties Svetlyanka (k), Memory Yakovleva, Yakovlevskaya, Chudelnitsa. The largest diameter of the conditional root neck when using the plant growth regulator succinic acid was characterized by the varieties of pear Svetlyanka (k), Memory Yakovleva, Yakovlevskaya, Chudesnitsa. This figure was 1.4 cm. The largest number of roots (from 8.0 to 8.6 pcs.) when treated with plant growth regulator succinic acid were the varieties of pear Svetlyanka (k), Memory Yakovleva, Yakovlevskaya, Chudelnitsa. When using the plant growth regulator succinic acid, the pear varieties Svetlyanka (k), Memory Yakovleva, Yakovlevskaya, Chudesnitsa had the highest root length (from 11.0 to 11.6 cm). Without the use of a plant growth regulator, the highest growth height (from 13.0 to 13.8 cm) was characterized by the varieties of pear Svetlyanka (k), Memory Yakovleva, Yakovlevskaya, Chudelnitsa. The largest diameter of the conditional root neck without treatment with a plant growth regulator was possessed by the pear varieties Svetlyanka (k), Memory Yakovleva, Yakovlevskaya, Chudelnitsa. This figure was 1.2 cm. Without the use of a plant growth regulator, the varieties Grushisvetlyanka (k), Memory Yakovleva, Yakovlevskaya, Chudesnitsa had the largest number of roots (from 6.0 to 6.5 pcs.). The largest root length (from 8.0 to 8.7 cm) without the use of a plant growth regulator was characterized by pear varieties Svetlyanka (k), Memory Yakovleva, Yakovlevskaya, Chudelnitsa.

The Application Timing of a Cytokinin B-Mo-based Product Affects the Characteristics of Rooted Cuttings and Nonstructural Carbohydrates of Coleus (Plectranthus scutellarioides cv. Wild Lime) during Adventitious Root Development

A large group of horticulture species are propagated vegetatively through shoot-tip cuttings harvested from stock plants and planted to form adventitious roots. Adventitious rooting leads to establishing a carbohydrate sink in the region of root regeneration that is highly dependent on energy and carbon skeletons. We hypothesized that the timing of exogenous applications of cytokinin (CK) and boron (B)–molybdenum (Mo)-based products during adventitious root development can affect the flow of sugars from leaves to sinks, carbon allocation to the adventitious roots, and the quality of rooted cuttings. During this project, we aimed to determine if the application time of a CK/B-Mo-based product during the adventitious root development of unrooted cuttings would impact the source-to-sink relationship and, hence, affect plug growth and quality. A sink-strengthening commercial product based on cytokinin, B, and Mo was applied at four plug development stages plus a negative control as follows: T1, plants without product (control); T2, sticking stage (starting 24 hours after the sticking); T3, callus formation stage; T4, root development stage; and T5, toning stage. The root and shoot lengths and dry matter, number of leaves, leaf chlorophyll content, root-to-shoot ratio (based on dry matter), and nonstructural carbohydrate contents were measured. The timing of the application of the product impacted the root development, quality of the cuttings, and nonstructural carbohydrate content. Product application during the adventitious root dedifferentiation and induction phases (T2) resulted in the shortest root and shoot lengths, lowest dry matter accumulation, lowest nonstructural carbohydrate contents, and some phytotoxicity. Application during the initiation phase (T3) resulted in greater root length, total dry matter, and total soluble sugar contents compared with the control. Application during the expression phase (T4) resulted in the largest root length and mass and the highest sucrose contents. Applying the product when the roots had grown and reached all the edges of the growing media (T5) did not have any benefits compared with the control. This study provides new insights into the application timing of exogenous CKs, B, and Mo to generate a well-toned rooted coleus cutting and potential explanations in relation to nonstructural carbohydrate metabolism.

Improvement of Seed Germination and Seedling Growth of Faba Bean (Vicia Faba L.) through Seed Priming

In a lab experiment using seed priming, the faba bean (Vicia faba L.) seed germination and seedling development were studied. Twenty different priming techniques were utilized in the study, each comprising varying concentrations of NaOCI, CaCl2, KNO3, Manitol, PEG, KCL, H2O and a control group that received no priming. Four replications of a completely randomized design (CRD) were used in the experiment. Among the three priming treatments, there were substantial differences in the seedling growth metrics and germination rate. When 500 ppm NaOCl was used as a treatment, the highest seed germination percentage (96%) was attained. Although 100 ppm PEG had the greatest germination index (42.92), 10000 ppm NaOCl had the quickest mean germination time (8.27). Additionally, at a concentration of 1500 ppm NaOCl, the greatest seedling vigor index (29.79) and maximum germination coefficient (12.28) were likewise obtained. With H2O treatment, the maximum shoot length (21.09 cm) was observed for seedling growth parameters. The largest root length was produced by a 10000 ppm KNO3 treatment (11.19 cm). With 20000 ppm KNO3, the maximum root dry weight was achieved (88.50 mg), whereas H2O produced the highest shoot dry weight (51.0 mg). Additionally, it was discovered that a treatment with 10000 ppm KNO3 had the best root-shoot ratio (0.72). The research thus supports the possible use of seed priming as a method to improve faba bean seed germination and seedling growth. NaOCl and KNO3 seemed to work best for faba bean seed germination and seedling growth.

ВОЗДЕЙСТВИЕ РЕГУЛЯТОРА РОСТА РАСТЕНИЙ КОРНЕВИНА НА УКОРЕНЯЕМОСТЬ СОРТОВ И ФОРМ ГРУШИ В УСЛОВИЯХ ИСКУССТВЕННОГО ТУМАНА

Pear is a seed crop that grows and is consumed all over the world, grows on trees and is harvested in the Northern Hemisphere from late summer to October. Plant growth regulators are such chemicals that are capable of various green and lignified cuttings to increase the root system, they are also able to increase yields. Kornevin is an effective plant growth regulator (phytohormone). It is a biological product that stimulates root formation. The drug has a mild effect, is not phytotoxic, eliminates overdoses. It has a long-lasting prolonged effect. Green pear cuttings K-1, K-2, OHF 333, Piro II had the greatest rootability when using the plant growth regulator kornevin (30.0 mg/l) (from 85.0 to 87.7%). Without the use of plant growth regulators, the forms K-1, K-2, OHF 333, Piro II had high rooting rates of green pear cuttings (from 70.5 to 75.9%). The highest growth height when using the plant growth regulator kornevin (30.0 mg/l) was possessed by the rootstock forms of the Caucasian pear, 4-26, 4-39, K-1, K-2, OHF 333, Piro II, this indicator varied from 12.5 to 14.0 cm. The largest diameter of the conditional root neck (from 1.3 to 1.6 cm) had the forms of pears Caucasian, 4-26, 4-39, K-1, K-2, OHF 333, Piro II and varieties ‘Pervomayskaya’, ‘Yakovlevskaya’, ‘Avgustovskaya Rosa’, ‘Irista’, ‘Chudesnitsa’, ‘Fevral'skiy Suvenir’. The largest number of roots (from 7.5 to 8.5 pcs.) were demonstrated by the forms of the Caucasian pear, 4-26, 4-39, K-1, K-2, OHF 333, Piro II. The largest root length (from 9.0 to 9.8 cm) was possessed by the rootstocks of the Caucasian pear, 4-26, 4-39, K-1, K-2, OHF 333, Piro II and varieties ‘Nika’, ‘Avgustovskaya Rosa’, ‘Irista’, ‘Fevral'skiy Suvenir’. Without the use of plant growth regulators, the largest plant height (from 10.0 to 12.0 cm) was possessed by the forms of Caucasian pear, 4-26, 4-39, K-1, K-2, OHF 333, Piro II. The largest number of roots (from 5.0 to 6.6 pcs.) had pear shapes 4-39, K-2, OHF 333, Piro II and varieties ‘Svetlyanka (k)’, ‘Nika’, ‘Pervomayskaya’. The largest root length without the use of plant growth regulators was characterized by the forms of the Caucasian pear, 4-26, 4-39, K-1, K-2, OHF 333, Piro II and varieties ‘Nika’, ‘Fevral'skiy Suvenir’, this indicator varied from 7.0 to 7.8 cm.

INFLUENCE OF DIFFERENT PREPARATIONS ON SOWING QUALITY OF SPRING WHEAT SEEDS

The article is devoted to the study of the effect of pre-sowing treatment with various preparations on germination, growth and development of spring wheat. Spring wheat seeds were pre-soaked for 24 hours in Biohumus liquid organomineral fertilizer and Chlorella Suspension growth stimulator, presowing treatment was also carried out with agromineral fertilizers - zeolite from the Tatarsko-Shatrashanskiy deposit and tripoli from Kaluga region. The experiments were conducted in laboratory conditions in vessels and rolls. An increase of germination energy and seed germination was noted in rolls, when seeds were soaked in biohumus and treated with zeolite - 45 and 22% higher than in the control. The maximum values of plant height were observed in the variant with zeolite - 9% higher than the control. The number of roots increased by 22%, their length in the variant with biohumus was, on average, 20% more than the control values. The coleoptile length was at the same level in all variants. The maximum germination in vessels was obtained in the variant with soaking seeds in chlorella suspension - 92%, which is 9.52% more than the control variant. The maximum plant height was observed in the variant with biohumus - 7% more than the control, the largest root length - in the variant with seed treatment with tripoli - 6% more than the control, and the largest number of roots in the variant with chlorella suspension and zeolite - 9% more than in the control variant.

Wheat cultivars with small root length density in the topsoil increased post-anthesis water use and grain yield in the semi-arid region on the Loess Plateau

Large distribution of roots in topsoil layers allow more uptake of soil water and nutrients during the vegetative growth, but it may be disadvantageous if soil water deficit develops during the reproductive stage. The relationship between the distribution of roots in topsoil (0–0.4 m) and soil water use, dry matter and nitrogen (N) accumulations, and grain yield was examined in winter wheat (Triticum aestivum L.) with contrasting root size in the topsoil. Two old landraces (CW134 and JM47, larger root length and biomass in the topsoil) and two modern wheat cultivars (CH58 and LH7, smaller root system size in the topsoil), were grown in the field during two seasons (2016–2017 and 2017–2018) under rainfed and irrigation conditions in the semi-arid farmland on the Loess Plateau. Root biomass and root length density (RLD) in topsoil (0–0.4 m) was significantly higher in the old landraces than in the modern cultivars (P < 0.05) under rainfed and irrigation in both seasons (no such difference in subsoil, 0.4–1.0 m). The modern cultivars had significantly higher grain yield, grain N concentration, water-use efficiency (WUE), and 1000-grain weight (P < 0.05). Seasonal water use was similar among all cultivars, but post-anthesis water use was higher in the modern cultivars, particularly under rainfed conditions in both seasons. Root biomass and RLD in the topsoil was positively correlated with pre-anthesis water use, but negatively correlated with after anthesis water use. Post-anthesis water use was closely related to post-anthesis dry matter, N accumulation, yield and WUE under rainfed conditions. To conclude, large distribution of roots in the topsoil had non-advantage for wheat grown under rainfed conditions. The small distribution of roots in the topsoil (characteristics of modern wheat cultivars) enhanced post-anthesis water use, increased post-anthesis dry matter and N accumulation, and hence attained higher grain yield and grain N when grown in the semi-arid environment.

MINI-CUTTINGS TECHNIQUE FOR VEGETATIVE PROPAGATION OF Dalbergia nigra

The usual propagation method for Dalbergia nigra is via seedings; however, the seasonal supply has a variable quantity of seeds which limits the continuous production of seedlings. Therefore, the objective of this study was to establish a vegetative propagation protocol via mini-cuttings technique for D. nigra from juvenile shoots obtained from seedlings. The experimental design was completely randomized in a 2 x 2 x 4 factorial scheme, with two geographical origins: two controlled release fertilizer doses (4.0 and 8.0 g.dm-³) and four indole-3-butyric acid (IBA) concentrations (0; 2,000; 4,000; and 6,000 mg.Kg-1), with four replications. The mini-cuttings were removed from the tubes after 60 days of propagation in the greenhouse, and the substrate was completely removed by washing in running water to observe the roots. The survival percentage, rooting, rooting speed and variables related to mini-cuttings vigor (largest root length (RL, cm.plant-1), number of roots (NR), surface area (SA, mm2), root volume (RV, mm³) and root dry mass (RDM, g.plant-1) were measured. The results indicated that D. nigra has an aptitude for vegetative propagation by mini-cuttings with survival values and rooting greater than 70%. Geographical origins present a different set of responses for survival, rooting and vigor of mini-cuttings. Stock plant nutrition influences mini-cuttings root growth. IBA concentrations did not promote an effect on the mini-cuttings rooting percentage; however, exogenous auxin at the dose of 6,000 mg.Kg-1 provided mini-cuttings with greater vigor in their radical system. Nonetheless, further research is suggested to define the feasibility of using this regulator in the vegetative propagation of this species.

The relationship between root system development and vernalization under contrasting irrigation in bread wheat lines with the introgressions from a synthetic hexaploid

The properties of the root system are especially important under drought, which is currently the most significant climate threat worldwide. The aim of this work was to investigate the relationship between the root system development and vernalization requirements under contrasting irrigation conditions in bread wheat using lines with alien introgressions. A set of single chromosome substitution lines Chinese Spring (Synthetic 6x, AABBDD) and D-genome derived introgression lines were used to study the relationships. It was found that 1A substitution resulted in a substantial reduction of root length and weight while 5D substitution, on the contrary, led to a significant increase compared to the recipient and the donor under both irrigation regimes. The greatest root weight, root length, and number of days to flowering were detected in the lines carrying a common introgression fragment of the 5D chromosome connected with the molecular marker Xgwm292 and the Vrn-D1 gene. The lines with the introgression in this region had a significantly larger root length and weight compared with the recipient and donor under all conditions of irrigation. The combination of prolonged vernalization and drought negatively affected the development of roots in all lines with the most pronounced effect on root weight. With the use of monosomic analysis, it was shown that the Vrn-A1 gene has a substantial reducing effect on the root length and weight. The revealed relationship between the flowering time and root system development can be used for breeding of wheat cultivars more adapted for growing in arid conditions.

Growth and production of basil under different luminosity and water replacement levels

ABSTRACT Basil is used as spice and for medicinal purposes. Its growth is influenced by environmental factors, mainly soil moisture and air temperature. Thus, this study was installed to evaluate growth and production of basil under different levels of luminosity and water replacement. The experimental design was completely randomized, with six replicates, arranged in split plot scheme, with three luminosity levels in the plots (full sun, 50% and 70% shading) and four water replacement levels in the subplots (25, 50, 75 and 100% ETc). We evaluated plant height, stalk diameter, number of leaves and branches, root system volume, the largest root length, fresh and dry mass of roots and leaves. Data were submitted to variance analysis to observe significant differences between treatments and interactions. Luminosity effects were evaluated using Tukey test (p≤0.05%) and the effects of water regime, with the aid of regression analysis. According to data, 50% shading and 100% water replacement, lost through crop evapotranspiration, resulted in higher values of plant height, stalk diameter, branch growth, fresh and dry mass of leaves, and number of leaves. Full sun environment and 100% water replacement provided an increase in root dry mass and volume.

Deep Placement of Nitrogen Fertilizer Affects Grain Yield, Nitrogen Recovery Efficiency, and Root Characteristics in Direct-Seeded Rice in South China

Deep placement of nitrogen (N) fertilizer has become one of the effective management practices for increasing crop yield and improving N recovery efficiency (NRE). However, it is unclear how different N fertilization depths affect grain yield, nitrogen use efficiency, and root characteristics in direct-seeded rice (DSR) in South China. Here, we conducted stainless steel-box experiment to evaluate the effects of different N fertilization depths at four fertilization depths (0, 4, 8, and 12 cm, written as D0, D4, D8, and D12, respectively) with a conventional ammonium bicarbonate fertilizer (TN???=???17.7%) (150 kg N ha???1) and a control (no N fertilizer applied, CK) on grain yield, NRE, and root characteristics of DSR. The results indicated that both D8 and D12 significantly increased grain yields by 72.91 and 81.84%, respectively, compared with CK. The highest nitrogen agronomic efficiency (NAE) and NRE were found under D12 treatment, which were increased by 165.42 and 129.45% compared to D0, respectively. We also found that deep placement of N fertilizer (both D8 and D12) could also promote rice root growth such as larger root length, root superficial area, and thicker root diameter. Furthermore, nitrate reductase (NR), glutamine synthetase (GOGAT), and glutamine synthetase (GS) activities of flag leaves at the heading stage were also increased. The result shows that both 8 and 12 cm are relatively reasonable fertilization depths depended on adopted rice varieties when ammonia bicarbonate fertilizer is used in DSR production.

Plant Nanobionic Effect of Multi-walled Carbon Nanotubes on Growth, Anatomy, Yield and Grain Composition of Rice

Oxidized multi-walled carbon nanotubes (MWCNTs) having a diameter of 14–30 nm and length of 200–300 nm were used to the prime rice seeds with different concentrations of MWCNT (70, 80 and 90 μg/mL). The effects on germination, growth, anatomy, physiology, yield, quantitative seed components and toxicity (using human cell lines) were evaluated. The treatments, when extended to realistic field environments, resulted in significantly better yield and productivity of rice. The MWCNT-treated plants had denser stomata and larger root length, which resulted in faster growth and facilitated both water and mineral uptake, thus boosting the crop yield. Increased vascular tissues enhanced the chlorophyll content and photosynthetic activity. No toxic effects of MWCNT were observed in the DNA of the CNT-treated plants, and in the human cell lines, treated with harvested grain extract of MWCNT-primed plants. This study provides some new insights into the use of nanomaterials in plants and their potential benefits in agriculture thus ushering in a new organic-inorganic interface.

阿拉善高原2种荒漠植物根系构型及生态适应性特征

根系构型决定了植物对资源的吸收方式，根系构型的变化是植物对环境的生态适应和有效生存策略。在阿拉善高原西南缘红砂（Reaumuria soongarica）-珍珠猪毛菜（Salsola passerina）混生群落采用传统挖掘法收集两种植物根系，基于量化的根系形态指标，利用几何拓扑学及分形理论分析了根系构型特征，探讨了该地区2种植物对干旱生境的生态适应策略。结果表明：红砂和珍珠猪毛菜根系均以水平分布占优，根系浅层化分布明显，混生的两种植物占据不同的生态位；2种荒漠植物均具有较大的比根长（SRL）和比表面积（SRA），红砂SRL=21.3 cm/g，SRA=7.6 cm²/g，珍珠SRL=22.4 cm/g，SRA=6.5 cm²/g，有利于水分和养分的获取；红砂根系拓扑指数（TI）、修正拓扑参数（q_a和q_b）分别为0.86、0.52、0.49，珍珠猪毛菜对应参数分别为0.93、0.76、0.73，表明2种植物根系均趋向于鱼尾形分支结构；根系分形维数值（FD_红=1.488、FD_珍=1.422）较小，而分形丰度值（lgK_红=1.855、lgK_珍=1.774）较大，表明2种植物分支相对简单，但空间拓展能力强，有利于对营养空间的占有。上述特征可能是阿拉善西南缘红砂-珍珠猪毛菜群落2种荒漠植物植物对干旱贫瘠生境的重要生态适应策略。;The change of root architecture is an effective means for plants to adapt to environment. In this study, the root of Reaumuria soongorica and Salsola passerina were harvested by destructive sampling in the Alxa Plateau. The root architecture characteristics and adaptive strategy to arid environment were analyzed by root morphological, topology and fractal indexes. The results showed that the roots of the two desert plants were dominated by horizontal distribution and occupied different ecological niches. Large specific root length (SRL) and specific root area (SRA) values of R. soongorica (SRL =21.3 cm/g, SRA =7.6 cm²/g) and S. passerine (SRL=22.4 cm/g, SRA=6.5 cm²/g) were beneficial to obtain water and nutrients. Both R. soongarica and S. passerine roots were herringbone-like (TI, q_a, q_b being 0.86, 0.52 and 0.49 for R. soongorica, while 0.93, 0.76, and 0.73 for S. passerine) and had obvious fractal characteristics (FD and logK being 1.488 and 1.855 for R. soongorica, while 1.422 and 1.774 for for R. soongorica), which indicated that they had simple root architecture and high ability to expand living space. Above root characteristics may be the important adaptive strategies to arid environment for R. soongorica and S. passerina in Alxa Plateau.

Potential Use of Eucalyptus Seedling in Recycling of Fish Farming Wastewater in Agriculture

Aims: The reuse of fish wastewater in agricultural activities such as the production of seedlings in commercial nurseries has great potential to minimize production costs and to reduce environmental impacts due to the inappropriate disposal of this waste. The objective of this study was to evaluate the growth, development and quality of Eucalyptus grandis W. Hill ex Maiden seedlings produced with different wastewater concentrations from fish farming.&#x0D; Study Design: The fertigation treatments were using fish farming (Tilapia) wastewater from tanks (FW), daily nutrient solution (DNS), and the combinations of 50% FW + 50% DNS, and 25% DNS + 75% FW, applied daily.&#x0D; Place and Duration of Study: The experiment was carried out from August to December 2016 at the Federal University of Technology of Paraná, Brazil.&#x0D; Methodology: The macro and micronutrient contents in leaf tissue, seedling height, stem diameter, the largest root length, leaf area, fresh and dry shoot and root mass and Dickson quality index were all evaluated.&#x0D; Results: The nutrient contents present in the leaf tissue were adequate for the nutritional demand of the eucalyptus. The seedling quality index (DQI) indicated that the daily nutrient solution (0.21) and 50% FW + 50% DNS (0.20) generated balanced seedlings regarding height and biomass accumulation.&#x0D; Conclusion: Fertigation of eucalyptus seedlings can be carried out with wastewater from fish farming, but it is necessary to complement the fertilization with other nutrient sources to produce quality seedlings which are suitable for field transplantation.

Differences in physiological and biochemical characteristics in response to single and combined drought and salinity stresses between wheat genotypes differing in salt tolerance.

The combined drought and salinity stresses pose a serious challenge for crop production, but the physiological mechanisms behind the stresses responses in wheat remains poorly understood. Greenhouse pot experiment was performed to study differences in genotype response to the single and combined (D + S) stresses of drought (4% soil moisture, D) and salinity (100 mM NaCl, S) using two wheat genotypes: Jimai22 (salt tolerant) and Yangmai20 (salt-sensitive). Results showed that salinity, drought and/or D + S severely reduces plant growth, biomass and net photosynthetic rate, with a greater effect observed in Yangmai20 than Jimai22. A notable improvement in water use efficiency (WUE) by 239, 77 and 103% under drought, salinity and D + S, respectively, was observed in Jimai22. Moreover, Jimai22 recorded higher root K+ concentration in drought and salinity stressed condition and shoot K+ under salinity alone than that of Yangmai20. Jimai22 showed lower increase in malondialdehyde (MDA) accumulation, but higher activities of superoxide dismutase (SOD, EC 1.15.1.1) and guaicol peroxidase (POD, EC 1.11.1.7), under single and combined stresses, and catalase (CAT, EC 1.11.1.6) and ascorbate peroxidase (APX, EC 1.11.1.11) under single stress. Our results suggest that high tolerance of Jimai22 in both drought and D + S stresses is closely associated with larger root length, higher Fv/Fm and less MDA contents and improved capacity of SOD and POD. Moreover, under drought Jimai22 tolerance is firmly related to higher root K+ concentration level and low level of Na+ , high-net photosynthetic rate and WUE as well as increased CAT and APX activities to scavenge reactive oxygen species.

Rooting of apical cuttings of Angelonia integerrima Sprengel: concentrations of indole-3-butyric acid and substrates

The objective of this study was to evaluate the effect of the concentration of indole-3-butyric acid (IBA) and substrates in the rooting of apical cuttings of Angelonia integerrima. Powder IBA was used at the concentrations 0, 500, 1,000, 2,000 and 4,000 mg kg-1, and two substrates containing carbonized rice husks (CRH) and commercial substrate based on Sphagnum peat were used. The number of rooted cuttings, shoot length, root system length, number of new leaves, root system volume, callus formation at the cutting base, and shoot and root dry matter were evaluated. The experimental design was completely randomized with a factorial design (5 IBA concentrations x 2 substrates). There were no interactions between the concentrations of IBA and the substrates. There was a difference only for the factor substrate. The cuttings presented an average rooting of 79%, with callus formation in 59.4% of them. The CRH substrate presented the highest shoot length and the highest number of new leaves. The commercial substrate resulted in a high average root volume, a large root length and a great increase in root dry matter. In the rooting by cutting of A. integerrima is not necessary to use IBA and the commercial substratum based on peat or CRH can be used.

Acclimatization and growth of ornamental pineapple seedlings under organic substrates

The in vitro propagation techniques are commonly used to produce ornamental pineapple seedlings in commercial scale, aiming to attend the growers with genetic and sanitary quality seedlings. However, the choice of the ideal substrate is essential for the acclimatization and growth stage of the seedlings propagated by this technique, since some substrates can increase the seedling mortality and/or limit the seedling growth due to its physical and chemical characteristics. Thus, the aim of this study was to evaluate the acclimatization of ornamental pineapple [Ananas comosus (L.) Merr. var. ananassoides (Baker) Coppens &amp; Leal] on different substrates. Seedlings with approximately seven centimeters, obtained from in vitro culture, were transplanted into styrofoam trays filled with the following substrates: sphagnum; semi-composed pine bark; carbonized rice husk; sphagnum + semicomposed pine bark; sphagnum + carbonized rice husk; and semi-composed pine bark + carbonized rice husk. Each treatment was replicated five times using 10 plants. At 180 days, there were evaluated the following variables: survival percentage, plant height, number of leaves, leaf area, largest root length, and shoot and root dry matter. The substrate semi-composed pine bark + carbonized rice husk presented the lowest mean (62%) for survival percentage. The semi-composed pine bark and semi-composed pine bark + carbonized rice husk treatments presented significant increments in some evaluated biometric characteristics. The semi-composed pine bark is the most favorable substrate for the A. comosus var. ananassoids acclimatization.

Root traits are related to plant water‐use among rangeland Mediterranean species

Summary Understanding the water‐use of plants is timely under increasing drought stress due to climate change. Despite the crucial role of roots in water uptake, relationships between water‐use and root traits are seldom considered. Combining a functional trait‐based approach with a water balance model, we tested whether root functional traits are related to spatial and temporal water‐use among 12 Mediterranean rangeland species grown in common garden monocultures. Soil water content was monitored for 10 months, and the dynamics of water uptake of each species was modelled at a daily time step. Root functional traits were measured at two soil depths (shallow and deep soil). Species with fast resource acquisition strategies in shallow soil, i.e. thin roots, maximised water uptake in a short period and consumed large amounts of water during periods of low water availability. Conversely, species with a more conservative root strategy, i.e. coarse roots, took up less water during the peak‐growing season, maintained water uptake over a longer period of time and consumed less water during periods of low water availability. Deep root traits are strongly related to species’ ability to take up water from deep soil. Deep roots with large diameters and low specific root length improve species’ ability to reach water from deep soil. Biomass investment in the deep soil layer was positively related to the amount of water consumed during periods of low water availability. Our results highlight that root functional traits influence a range of spatial and temporal water‐use among Mediterranean rangeland species. They account for the amount of water taken up during dry periods but not during the entire growing season. A lay summary is available for this article.

Revealing new insights into different phosphorus-starving responses between two maize (Zea mays) inbred lines by transcriptomic and proteomic studies

Phosphorus (P) is an essential plant nutrient, and deficiency of P is one of the most important factors restricting maize yield. Therefore, it is necessary to develop a more efficient program of P fertilization and breeding crop varieties with enhanced Pi uptake and use efficiency, which required understanding how plants respond to Pi starvation. To understand how maize plants adapt to P-deficiency stress, we screened 116 inbred lines in the field and identified two lines, DSY2 and DSY79 that were extreme low-P resistant and sensitive, respectively. We further conducted physiological, transcriptomic, and proteomic studies using the roots of DSY2 and DSY79 under normal or low-P conditions. The results showed that the low-P resistant line, DSY2 had larger root length, surface area and volume, higher root vitality, as well as acid phosphatase activity as compared with the low-P sensitive line, DSY79 under the low-P condition. The transcriptomic and proteomic results suggest that dramatic more genes were induced in DSY2, including the plant hormone signaling, acid phosphatase, and metabolite genes, as compared with DSY79 after being challenged by low-P stress. The new insights generated in this study will be useful toward the improvement of P-utilize efficiency in maize.

Different propagules and auxin concentration on rooting of passionflower sandbank

ABSTRACT Passiflora mucronata Lam. is resistant to Fusarim oxysporum f. passifloraceae and therefore can be used as rootstock for the species Passiflora edulis Sims. f. flavicarpa. The rootstocks in this case can be vegetatively propagated through cuttings. The objective of this study was to evaluate the effect of different types of cuttings and different concentrations of indole-3-butyric acid (IBA) on the adventitious rooting of P. mucronata. The experiments were arranged in a completely randomized design with four replications of 16 cuttings each. In Experiment 1, the treatments consisted of the different types of cuttings from mother plants grown in protected environment: shoot tips; two leaves and two nodes; one leaf and one node; leafless with two nodes; leafless with one node. In Experiment 2, the cuttings were taken from field plants and treated with the following IBA concentrations: 0; 1000 mg kg-1 (0.0036456 mol L-1); 1500 mg kg-1 (0.0054684 mol L-1) and 2000 mg kg-1 (0.0072912 mol L-1). The characteristics evaluated in the experiments 1 and 2 were: survival (1 and 2); budding (1 and 2); shoot number (2), shoot length (2), number of shoot leaves (2);shoot dry mass (2); callusing (1); rooting (1 and 2); root number (1 and 2), largest root length (1 and 2), root volume (1 and 2), and root dry mass (1 and 2). We found that, instead the shoot tips, the cuttings of the type leafless with two nodes are the best for P. mucronata rooting. Neither the cuttings from greenhouse plants nor the cuttings from field plants require growth regulators for rooting of P. mucronata cuttings of the type leafless with two nodes.