Root Dry Mass Accumulation Research Articles

Fertirrigação com cobre na cultura da beterraba em região semiárida

ABSTRACT Copper is an essential element for beet; however, it needs to be made available in adequate quantities since this nutrient, which is a heavy metal, can cause toxicity to plants and/or humans. This study aimed to evaluate the agronomic performance of beet fertigated with copper in a semi-arid region of Brazil. Two experiments were carried out in complete randomized blocks, with five treatments (0, 1.5, 3.0, 4.0, and 6.0 kg ha-1 of copper) and four replicates. In 2019, the copper content was within the adequate range for beet. In 2021, fertigation with copper above 0.8 kg ha-1 led to contents in the phytotoxicity range, which may explain the reduction in total and tuberous root dry mass accumulation. Fertilization with copper increased marketable yield in 2019 (17.32 t ha-1 at the dose of 3.9 kg ha-1 of copper), while, in 2021, there was no fit of the equations. Copper fertilization altered the tuberous root pH but did not influence the other tuberous root quality components. Plants fertilized with copper accumulated more copper in the leaves than in the tuberous root, with a maximum accumulation of 6.0 kg ha-1 of copper in 2019 and 2021. Fertilization with 3.9 kg ha-1 suits soils with low copper content.

Nutrient interactions influence the efficacy of biostimulants

Improved predictability of the effectiveness of biostimulant products is required before their wider acceptance by ornamental plant growers. We investigated the effects of three of the main groups of biostimulants (humic acids, protein hydrolysates, and seaweed extracts) under six fertilization levels, using Antirrhinum majus L. as a model ornamental plant to evaluate potential interactive effects on plant performance and growth substrate biological activity. Number of leaves increased in response to biostimulant application, but leaf area was generally reduced, especially in potting mix with lower fertility. Seaweed extract had beneficial effects on both shoot and root dry mass accumulation but was less beneficial than higher fertilizer rates. The beneficial effects of protein hydrolysates and humic acids were marginal and less predictable under our experimental conditions; humic acids showed particularly negative effects on root dry mass accumulation. All biostimulants showed negative impacts on substrate microbial activity, although Dehydrogenase Activity (DHA) was substantially higher under lower fertility. Extrapolation of the results of this study suggests that it is feasible to apply biostimulants, particularly seaweed extracts, to improve the overall growth performance of ornamental plants. However, it is essential to consider the nutrient status of growth medium if we are to leverage the biostimulant paradigm in the ornamental plant sector.

Biostimulants in the development of tomato and collard greens seedlings

The success of crop yields begins with the use of quality seedlings. Crops from vigorous plants respond better to phytosanitary treatments and management techniques, resulting in economic returns and better use of inputs. The objective of this study was to evaluate NPK fertilizer rates and rates of an NPK + auxin biostimulant on the effects over agronomic features of Collard Greens and salad tomato seedlings. The research consisted of two experiments in randomized block, with four replications each. Both experiments were in factorial scheme 2 x 4, consisting of the combination of two nutrient sources (NPK fertilizer 9-45-11 and biostimulant composed of NPK 9-45-11 + 400 mg kg -1 of auxin IAA), and four rates, being then 50; 100; 150 and 200% of the recommended rate of biostimulant for tomato and 50; 75; 100 and 125% of the recommended rate for Collard Greens. The biostimulant favored the development of tomato seedlings, since it provides greater root dry mass accumulation and didn’t promote seedling shedding, as it occurred in the application of NPK fertilizers. On the other hand, the Collard Greens seedlings didn’t distinguish by the presence of auxin in the biostimulant, developing greater seedlings heights with NPK application. Concentrations of 50-200% of the recommended biostimulant fertilizer didn’t interfere on root length, diameter and root dry mass of Collard Greens.

Weed Interference on Growth and Leaf Nutrient Accumulation in Two Cassava Varieties

The development of cassava varieties with more efficient nutrient absorption can prevent losses caused by weed competition. The objective of this study was to evaluate dry matter accumulation and leaf nutrient content in traditional and improved cassava varieties, with and without coexistence with weeds throughout the cycle. A randomized complete block design was used in a 2 x 2 x 11 factorial scheme with four replications. The first factor consisted of two varieties (Baianinha and Clone 56-03); the second factor was composed of the conditions with and without coexistence with weeds, and the third factor was 11 harvest periods. Coexistence with weeds reduced leaf contents of N (20.8% and 24.8%), P (26.7% and 4.6%) and K (27.1% and 12.6%) for 'Baianinha' and 'Clone 56-03', respectively. For coexistence with 'Baianinha', the period up to the maximum daily nutrient accumulation rate (N, P and K) ranged from 82 to 99 days after planting (DAP), while for 'Clone 56-03', coexistence in this period ranged from 80 to 88 DAP. The plants from the variety 'Clone 56-03' presented higher total dry mass and root dry mass accumulation, as well as higher leaf contents of N, P and K than the traditional cassava variety 'Baianinha', especially when in coexistence with weeds during the whole cycle.

Anatomical, morphological and growth responses of Thinopyrum ponticum plants subjected to partial and complete submergence during early stages of development.

Seedling recruitment and growth of forage grasses in flood-prone grasslands is often impaired by submergence. We evaluate the responses of Thinopyrum ponticum (Podp.) Barkw. & Dewey to partial and complete submergence at two early stages of development. Two greenhouse experiments were carried out with plants at three expanded leaves (Experiment 1) or five expanded leaves stage (Experiment 2). In each case, three treatments were applied for 14 days: control (C), partial submergence (PS; water level to half plant height), and complete submergence (CS; water level to 1.5 times plant height). Submergence was followed by a recovery period of 14 days at well drained conditions. Assessments included plant survival, height, leaf blade and pseudostem length, soluble carbohydrates in pseudostem, and shoot and root dry mass accumulation at the beginning and end of the submergence, and at the end of the recovery period. Root aerenchyma formation was determined on day 14 in both experiments. Under PS all plants survived, and the impact of the stress was related to the plants' developmental stage. However, plants with five expanded leaves increased total plant biomass with respect to control by 48%, plants with three expanded leaves reduced it by the same percentage. This response could be related to a higher ability to form root aerenchyma (17 vs 10%), and an enhanced leaf de-submergence capacity due to promoted leaf blade and pseudostem lengthening. Complete submergence treatment compromised the survival of 70% of the individuals with three expanded leaves but did not affect the survival at the five expanded leaves stage. In any developmental stage (three or five expanded leaves) plants fail to promote enough elongation of leaf blades or pseudostems to emerge from the water, so that always remained below the water surface. Root aerenchyma was not increased by CS at either of these two plant developmental stages. The high amount and concentration of pseudostem total soluble carbohydrates of the larger (five expanded leaves) plants facilitated their recovery growth after submergence. Our results predict the successful introduction of this species in areas where water excesses can cause soil waterlogging or shallow-partial plant submergence, but suggest avoidance of areas prone to suffer high-intensity flooding that lead to full plant submergence as this would highly constrain plant recruitment.

Light environment influences the flood tolerance in Cordia americana (L.) Gottschling & J.S.Mill.

The subtropical riverine forests present a variation in soil water availability throughout the year, following precipitation seasonality. The objective of this work was to evaluate the responses of Cordia americana to different light intensities combined with soil flooding. Seedlings were acclimated to light treatments, with full sun and shade conditions. Sun and shade plants were subjected to soil flooding during periods of 10 (short) and 30 (longer) days. After 10 days, flooded plants had a higher root dry mass accumulation and soluble sugars content, regardless of the light condition. Shade plants presented higher shoot soluble sugars content in relation to the sun plants. After 30 days, a higher shoot soluble sugar content was observed in sun and shade flooded plants. In addition, a higher root soluble sugar content was also observed in sun plants under flood. Periods of short flooding, characterized in subtropical forests as from 5 to 15 days, favor the growth of shade plants and the roots sugar accumulation, fact that can explain the species distribution. However, long periods of flooding may be associated with light environment plasticity, suggesting that the sun plants present a higher flooding tolerance, directly associated with the ability to maintain the sugar content.

Root-to-Shoot Communication to Modulate Source-Sink Relationship in Tomato Depends on Phytochromes

Phytochromes have been reported as strategic photoreceptors that can modulate the partition of photoassimilates between source and sink. However, so far, it is unknown whether phytochrome accumulation in the root is part of the control mechanisms of the source-sink relationship that modulates root and shoot growth. Thus, the objective of this work was to investigate phytochrome involvement in the source-sink relationship and in the vegetative and reproductive development of tomato plants (Solanum lycopersicum L. cv. Micro-Tom or MT). The experimental design was completely randomized with four treatments, provided by grafting combinations between aurea (au), which is phytochrome deficient, and the near isogenic line MT: (MT/MT, au/au, MT/au and au/MT). We observed differentiated responses for many parameters analyzed. For example, the root dry mass accumulation and stern diameter obtained by MT/MT, MT/au and au/MT grafting were 33% and 31% higher, respectively, than those obtained by au/au. In the au/MT combination, there were greater root dry mass and total dry mass accumulations. Based on the changes in vegetative and reproductive development observed from grafting combinations between MT and the mutant au, we can conclude that phytochromes function in the control of photoassimilate partitioning between roots and stems during tomato growth.

Application of SiO2 nanoparticles as pretreatment alleviates the impact of drought on the physiological performance of Prunus mahaleb (Rosaceae)

We studied the physiological responses of Prunus mahaleb (Mahaleb) seedlings to drought stress when previously irrigated (or not) with different concentrations of SiO2 nanoparticles (SNPs). SNPs were applied at four concentrations (0, 10, 50 and 100 mg L-1) for 45 days, and then seedlings were subjected to three watering treatments including low (300 mL water every 3 d), moderate (150 mL water every 3 d) and severe drought stress (no irrigation) for 19 days. Results showed that gas exchange – photosynthesis, stomatal conductance, and transpiration rate – were significantly less impacted by severe drought stress when seedlings were pretreated with SNPs at high concentrations. Beneficial effects of SNPs pretreatment were evident in the nutritional status of the plants as the concentration of N, P and K, were maintained at similar levels than in well-watered seedlings. Pretreated seedlings were able to maintain the root length and to reduce the impact of severe drought on root dry mass accumulation. Therefore, application of SNPs as pretreatment should be considered as a promising agronomic practice in sites prone to suffer from water deficit.

Nitrogen, potassium, calcium and sulfur omission in grass Convert

Intensive use of Brazilian pastures without the maintenance of soil fertility has decreased their productivity and favoring the onset of symptoms of nutritional deficiency. The objective of this study was to evaluate the effect of nitrogen, potassium, calcium and sulfur omission in symptomatology, growth and dry mass accumulation in grass Convert. The experiment was conducted in a greenhouse with a completely randomized design, with five treatments and four replications. The treatments were: full nutrient solution, nitrogen omission (N), potassium omission (K), calcium omission (-Ca) and sulfur omission (S). The variables were the number of tillers, leaf number, root size, shoot height, characterization of symptoms of deficiency and shoot and root dry mass accumulation. The data were submitted to the F test by analysis of variance and comparison of means by Tukey’s test (p <0.05). The omission of N, K, Ca and S limited the development of Convert grass compared to the full nutrient solution treatment, reducing the number of leaves, tillers, height, root size and dry mass production. The nutrient omission modified forage morphology, showing visual symptoms of deficiency of each nutrient evaluated. The decreasing order of onset of symptoms was N, Ca, S and K.

Early root development of poplars (Populus spp.) in relation to moist and saturated soil conditions

ABSTRACTPoplars (Populus spp.) are among the fastest growing trees raised in temperate regions of the world. Testing of newly developed cultivars informs assessment of potential planting stock for local environments. Initial rooting by nine poplar clones was tested in moist and saturated soil conditions during an 18-day greenhouse experiment. Clones responded differently to soil moisture, particularly in number of roots, root distribution, and root dry mass accumulation. About 73% of cuttings planted in moist soil produced roots from callus tissue, whereas only 1% of cuttings planted in saturated soil developed such roots. This drove root distribution towards the basal section of cuttings in moist soil, while in saturated soil roots were more evenly distributed among all three below-ground sections of cuttings. Roots originating from the basal section of cuttings planted in moist soil were longer than roots originating from apical and middle sections. Conversely, roots from the apical and middle sections of cuttings planted in saturated soil were longer than those originating from the basal section. Initial rooting among poplar clones established under two soil moisture regimes has implications for genotype deployment in the field, but long-term effects in the field are still unknown.

Growth, biomass allocation and photosynthetic responses are related to intensity of root severance and soil moisture conditions in the plantation tree Cunninghamia lanceolata.

We employed the warm temperate conifer Cunninghamia lanceolata (Lamb.) Hook. as a model of plantation forest species to investigate ecophysiological responses to root treatments (control (0%), and ∼25, 50 or 75% of the initial root mass) under well-watered and water-limited conditions. Our results indicated that total root dry mass accumulation was negatively associated with the severity of root pruning, but there was evidence of multiple compensatory responses. The plants exhibited higher instantaneous and long-term (assessed by carbon isotope composition, δ(13)C) water-use efficiency in pruning treatments, especially under low water availability. Root pruning also increased the fine root/total root mass ratio, specific root length and fine root vitality in both water availability treatments. As a result of the compensatory responses, under well-watered conditions, height, stem dry mass accumulation, leaf/fine root biomass ratio (L/FR), transpiration rate, photosynthetic capacity and photosynthetic nitrogen-use efficiency (EN) were the highest under 25% pruning. Yet, all these traits except L/FR and foliage nitrogen content were severely reduced under 75% pruning. Drought negatively affected growth and leaf gas exchange rates, and there was a greater negative effect on growth, water potential, gas exchange and EN when >25% of total root biomass was removed. The stem/aboveground mass ratio was the highest under 25% pruning in both watering conditions. These results indicate that the responses to root severance are related to the excision intensity and soil moisture content. A moderate root pruning proved to be an effective means to improve stem dry mass accumulation.

Selection of full-sib families of Panicum maximum Jacq under low light conditions

The silvopastoral system is a viable technological alternative to extensive cattle grazing, however, for it to be successful, forage grass genotypes adapted to reduced light need to be identified. The objective of this study was to select progenies of Panicum maximum tolerant to low light conditions for use in breeding programs and to study the genetic control and performance of some traits associated with shade tolerance. Six full-sib progenies were evaluated in full sun, 50% and 70% of light reduction in pots and subjected to cuttings. Progeny genotypic values (GV) increased with light reduction in relation to plant height (H) and specific leaf area (SLA). The traits total dry mass accumulation (DM) and leaf dry mass accumulation (LDM) had GV higher in 50% shade and intermediate in 70% shade. The GV of tiller number (TIL) and root dry mass accumulation (RDM) decreased with light reduction. The highest positive correlations were obtained for the traits H and RDM with SLA and DM; the highest negative correlations were between TIL and SLA and RDM, and H and LDM. The progenies showed higher tolerance to 50% light reduction and, among them, two stood out and will be used in breeding programs. It was also found that it is not necessary to evaluate some traits under all light conditions. All traits had high broad sense heritability and high genotypic correlation between progenies in all light intensities. There is genetic difference among the progenies regarding the response to different light intensities, which will allow selection for shade tolerance

Growth analysis of Fafia in relation to the propagation method used

A trial was carried out in Campinas, Brazil, from August 2005 to August 2006, in order to analyze the effect of two propagation methods (seeds and cuttings) on the development of Pfaffia glomerata (Spreng.) Pedersen. The experimental design was a completely randomized block, with five replications, and two methods of plant propagation. Plant height, aerial part dry mass and root dry mass were evaluated. Plants propagated from cuttings showed greater accumulation of dry mass on the aerial part. Root dry mass accumulation curves showed an exponential pattern, and at the end of the experimental period, the average of roots dry mass for both treatments were similar, up to 349,65 g plant-1.