Root Length

The pathogenicity and reproductive fitness of Pratylenchus coffeae and Radopholus arabocoffeae from Vietnam on coffee (Coffea arabica) seedlings cv. Catimor were evaluated in greenhouse experiments. The effect of initial population densities (Pi = 0, 1, 2, 4, 8, 16, 32, 64, 128, and 256 nematodes per cm3 soil) was studied for both species at different days after inoculation (dai). The data were adjusted to the Seinhorst damage model Y = m + (1-m).zPi-T. Tolerance limit (T) for P. coffeae was zero for the height and the diameter of the coffee plants. For the diameter, the T-value for R. arabocoffeae was 25.6 for 30 and 60 dai and 12.8 for 90 and 120 dai. After 4 months T was zero. The low tolerance limits indicate that Arabica coffee is highly intolerant to both nematode species. At the end of the experiment (180 dai), all plants were infected and most were dead when inoculated with R. arabocoffeae at initial densities of 32, 64, 128 and 256 nematodes/cm3 soil. For P. coffeae plant death was already observed at the lowest inoculation densities. Growth of coffee was reduced at all inoculation levels for both species. Pratylenchus coffeae and R. arabocoffeae caused intense darkening of the roots, leaf chlorosis and a strong reduction of root and shoot growth. It was observed that P. coffeae mainly destroyed lateral roots rather than tap roots, whereas R. arabocoffeae reduced tap root length rather than the lateral roots. At the lowest inoculum densities, the reproduction factor of P. coffeae was 2.38 and 2.01 for R. arabocoffeae, indicating that arabica coffee is a host for both species. Plant growth as expressed by shoot height and shoot and root weight measured 60 dai was negatively correlated with nematode (both species) density as expressed by the geometric mean of nematode numbers at 30 and 60 dai.

A two year field experiment was conducted to investigate the effect of different tillage methods on soil physical properties and crop yield of watermelon. Tillage treatments in the study were moldboard plow + two passes of disk harrow as conventional tillage (CT), two passes of disk harrow as reduced tillage (RT), one pass of disk harrow as minimum tillage (MT) and no-tillage (NT) as direct drilling method. The statistical results of the study indicated that tillage method significantly (P≤0.05) affected crop yield, fruit weight, fruit length, fruit diameter and total soluble solids, but there was no significant differences in other components such as number of plants per hectare, number of fruits per plant, root length and root dry matter. The maximum value of crop yield (21.11 t ha), number of plants per hectare (2730), fruit weight (5.15kg), fruit diameter (20.3cm), root length (42.0cm) and root dry matter (54.1%) was observed in case of CT treatment, while maximum value of numbe...

Caffeine (1,3,7-trimethylxanthine), a purine alkaloid found naturally in over 100 plant species, has recently been viewed as a safe chemical for management of pests including molluscs, slugs, snails, bacteria, and as a bird deterrent. It possesses phytotoxicity against plant species, yet the mechanism of action is lacking. A study was conducted to determine the effect of caffeine on the rooting of hypocotyl cuttings of mung bean (Phaseolus aureus) and the associated biochemical changes. At lower concentrations (<1,000 μM) of caffeine, though rooting potential was not affected, yet there was a significant decrease in the number of roots and root length. At 1,000 μM caffeine, there was a 68% decrease in the number of roots/primordia per cutting, whereas root length decreased by over 80%. However, no root formation occurred at 2,000 μM caffeine. Further investigations into the biochemical processes linked to root formation revealed that caffeine significantly affects protein content, activities of proteases, polyphenol oxidases (PPO) and total endogenous phenolic (EP) content, in the mung bean hypocotyls. A decrease in rooting potential was associated with a drastic reduction in protein content in the lower rooted portion, whereas the specific activity of proteases increased indicating that caffeine affects the protein metabolism. Activity of PPO decreased in response to caffeine, whereas EP content increased significantly indicating its non-utilization and thus less or no root formation. Respiratory ability of rooted tissue, as determined through TTC (2,3,5-triphenyl tetrazolium chloride) reduction, was impaired in response to caffeine indicating an adverse effect on the energy metabolism. The study concludes that caffeine interferes with the root development by impairing protein metabolism, affecting activity of PPO (and thus lignification), and EP content, which are the crucial steps for root formation.

The effect of four phosphate-solubilizing bacteria (PSB), (Burkholderia gladioli 10216, Burkholderia gladioli 10217, Enterobacter aerogenes 10208 and Serratia marcescens 10238) as identified on the basis of 16S rRNA gene sequencing was evaluated on plant growth and commercially important glycosides, stevioside (ST) and rebaudioside-A (R-A) of Stevia rebaudiana in pots containing tricalcium phosphate (TCP) supplemented soil. The PSB were isolated from the rhizosphere of S. rebaudiana plants and tested for P-solubilization ability, biocompatibility, indole acetic acid (IAA) and siderophore production. In greenhouse study, treatment of either individual PSB or a consortium (of PSB) resulted in increased plant growth, ST and R-A contents. The stimulatory effect was observed with consortium treatment in plant growth parameters (shoot length, 22.5%; root length, 14.7%; leaf dry weight, 89.0%; stem dry weight, 76.3% and shoot biomass, 82.5%) and glycoside contents (ST, 150% plant−1 and R-A, 555% plant−1) as compared to the un-inoculated plants. Among individual PSB treatments, B. gladioli 10216 showed most promising response in majority of the parameters studied. The root colonization potential of PSB, assayed by RAPD technique, showed the colonization of all PSB isolates, though their extent of colonization varied.▶ Phosphate-solubilizing bacteria were isolated from the Stevia rhizosphere. ▶ Isolates belong to genera Burkholderia, Enterobacter and Serratia. ▶ Isolates enhanced the plant growth, stevioside and rebaudioside-A content. ▶ Stimulatory effect was observed on the soil and plant phosphorus content. ▶ Consortium treatment showed better results than individual treatments.

Nursery practice using microbial inoculants was performed to find out the efficacy of the inoculants on seed germination and seedling growth of sissoo (Dalbergia sissoo Roxb.). Microbial inoculants or effective microorganisms (EM) are a mixture of many different beneficial microorganisms in a solution. The seedlings were grown in a mixture of sandy soil and cowdung (3:1) kept in polybags with

In the tropics, seasonally flooded forests (SFF) harbor fewer tree species than terra firme (i.e. non-flooded) forests. The low species diversity of tropical flooded forests has been ascribed to the paucity of species with adaptations to tolerate flooding. To test the hypothesis that flooding is the only factor restricting most species from SFF, we compared plant morphological and physiological responses to flooding in 2-month old seedlings of 6 species common to SFF and 12 species common to terra firme forests. Although flooding impaired growth, total biomass, maximum root length and stomatal conductance in most species, responses varied greatly and were species-specific. For example, after 90 days, flooding reduced leaf area growth by 10–50% in all species, except in Tabebuia, a common species from non-flooded habitats. Similarly, flooding had a 5–45% negative effect on total biomass for all species, except in 1 SFF and 1 terra firme species both of which had more biomass under flooding. A principal component analysis, using the above responses to flooding, provided no evidence that SFF and terra firme species differed in their responses to flooding. Flooding also caused reductions in root growth for most species. Rooting depth and root: shoot ratios were significantly less affected by flooding in SFF than in terra firme species. Although flood tolerance is critical for survival in flooded habitats, we hypothesize that responses to post-flooding events such as drought might be equally important in seasonal habitats. Therefore, we suggest that the ability to grow roots under anoxia might be critical in predicting success in inundated habitats that also experience a strong dry season.

An experiment on virus free in vitro banana plantlets production by the meristem cultured from virus infected four month old banana suckers cv. Amritasagar were used as explants. Four levels of BAP (0, 3, 4 and 5 mg/l), 5 levels of NAA (0.0, 1.0, 1.5, 2.0 and 2.5 mg/l) were used as treatment for shoot proliferation in experiment-I and Four levels of IBA (0, 1, 2 and 3 mg/l), 4 levels of NAA (0, 2, 3 and 4 mg/l) were used for root formation in experiment-II. ELISA test was conducted for the confirmation of virus eradication rate of regenerated plants and survival rate of regenerated plants in experiment-III. A significant variation was found among the treatments. Studies on the different concentrations of BAP + NAA on shoot proliferation and differentiation, reveals that 4 mg/l BAP + 1.5 mg/l NAA produced the greater number of shoots (4.58/ explant), the longest shoot (3.56 cm) and the highest numbers of leaves (3.11/explant). On the contrary, plantlets were cultured on half strength...

Iris Yedidia1, Alok K Srivastva1, Yoram Kapulnik2 & Ilan Chet1,3 1Department of Plant Pathology and Microbiology, Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew University of Jerusalem, Rehovot 76100, Israel. 2Department of Agronomy and Natural ...

Bacterial strains from chitin/chitosan-rich soils, from two industries, were screened for their chitinolytic, antifungal, and mineral phosphate solubilization abilities. The isolate SMA-1-SDCH02, positive for all three properties, was selected and identified as Paenibacillus elgii based on morphological and biochemical characters and supported by 16S rRNA gene sequence analysis. P. elgii enhanced the growth of groundnut in terms of shoot height, root length, total chlorophyll, and fresh and dry weight when applied alone or in combination with chitosan. The plant growth-promoting activity of P. elgii was seen in tobacco in a specially designed gnotobiotic setup indicating its capability to promote growth of at least groundnut and tobacco. Metabolite changes in the bacteria, studied using attenuated total reflectance-infrared (ATR-IR) spectroscopy, revealed split bands of amide I at the 1659- and 1636-cm−1 regions when grown in minimal media amended with tobacco root exudates. The difference in ATR-IR bands in the presence of tobacco root exudates indicated production of compounds with differences in functional groups.

This research was planned to study the effect of various concentrations of BAP and sucrose on in vitro potato (Solanum tuberosum L.) microtuber induction. Explants from in vitro grown plants were cultured on Murashige and Skoog (1962) medium supplemented with iron (150 ...

This work aimed to accomplish the in vitro propagation of Brazilian orchids on a simplified culture medium in order to acquire quality and economical propagation. The culture media tested were: MS, MS modified with half-macronutrients and a simplified culture medium with commercial fertilizer formulation NPK (6-6-8) 3 mL L- 1 . Three Brazilian species were used: Oncidium nanum, Laelia lundii

Plant growth promoting rhizobacteria (PGPR) stimulate plant growth and development by different mechanisms, including the production of different classes of signaling molecules, which may directly affect plant morphogenesis. Here, we report the effects of inoculation of Arthrobacter agilis UMCV2, a PGPR isolated from the rhizosphere of maize plants on growth and development of Medicago sativa seedlings. A. agilis UMCV2 inoculation promoted growth in M. sativa plants as revealed by increased stem length, root length and plant biomass. Inoculation of A. agilis using divided Petri plates decreased taproot growth and increased lateral root formation in plants grown in separate compartments suggesting a role of volatile organic compounds (VOCs) produced by this bacterium in root development. The analysis of VOCs produced by A. agilis UMCV2 identified N,N-dimethyl-hexadecanamine (dimethylhexadecylamine), an amino lipid structurally related to bacterial quorum-sensing signals, which modulated A. agilis UMCV2 growth and plant development in a dose-dependent way. Taken together, our results indicate that bacterial VOCs can be perceived by legume plants to modulate growth and morphogenetic processes and identify a novel signaling molecule potentially involved in plant-rhizobacterial interactions.

The objective of this work was to evaluate the influence of the number of leaves and test the effect of different doses of IBA (indolbutiric acid) in cutting propagation of acerola. The experimental design was entirely randomized, in a factor arrangement (5 X 3), with five different concentration of IBA (0, 1600, 2000, 2400 and 2800 mg.L-1) and three different types of cuttings (without leaves, one pair of leaves and two pairs of leaves). The cuttings were obtained from plants of the UFLA's orchard collection, padronized with 15 cm of length and treated with solution of IBA for 5 seconds. After that, they were taken to polypropylene trays filled with vermiculite and stayed under greenhouse conditions for 100 days. Rooting percentage, roots length, number of leaves and roots dry matter were evaluated. The presence of leaves is important for the rooting of aceroleira cuttings, in cuttings without leaves it didn't occur the formation of roots. Aceroleira cuttings with two pairs of leaves, treated with 2800 mg.L-1 of IBA presented larger rooting percentage (50%) and length of the roots (9 cm). The concentration of 2800 mg.L-1 of IBA provided larger number and dry matter of the roots for aceroleira rooting. The two pairs of leaves in aceroleira rooting provided larger number and dry matter of the roots.

O objetivo deste trabalho foi avaliar o efeito do tratamento de sementes com inseticidas e um bioestimulante na germinação no crescimento da planta e raiz de soja. Foram realizados dois experimentos em delineamento de blocos ao acaso, em que as sementes foram tratadas com aldicarb, thiametoxan, imidacloprid e duas testemunhas: uma sem produto e uma com bioestimulante. Em laboratório, as unidades experimentais constituíram-se de rolos de papel toalha com sementes de soja, para avaliar o vigor, a germinação, as plantas anormais e mortas, o comprimento de radículas e de plântulas. Nos testes em casa de vegetação, as unidades experimentais constituíram-se de tubos de PVC, com volume de 16 dm³, e foram avaliados: os teores de N, P e K; a matéria seca; o comprimento, a área e o raio médio radicular; a eficiência de absorção de N, P e K; e a taxa de crescimento radicular da soja. Os tratamentos de sementes de soja com os inseticidas e o bioestimulante levam à formação de raízes mais finas,...