Boron deficiency inhibits petiole and peduncle cell development and reduces growth of cotton

The effect of boron (B) on cotton growth and fruit shedding may be due not only to physiological or biochemical effects, but also to vascular tissue malformation. This experiment investigated petiole and floral peduncle anatomical alterations and growth of cotton supplied with deficient and sufficient B in nutrient solution. Cotton (Gossypium hirsutum cv. 'Delta Opal') plants were grown in solutions containing 0, 1.5, 3.0, 4.5, and 6.0 mu mol L-1 of B from 22 to 36 d after plant emergence (DAPE). From 36 to 51 DAPE, B was omitted from the nutrient solution. Petioles from young leaves and floral bud peduncles (first position of the first sympodial) were sampled and the cross-section anatomy observed under an optical microscope. The number of vascular bundles of the petiole was decreased in B-deficient plants and the xylem was disorganized. Phloem elements in the peduncle vascular cylinder of B-deficient plants did not show clear differentiation. The few xylem elements that were formed were also disorganized. Modifications caused by B deficiency may have impaired B and photosynthate translocation into new cotton growth. Boron accumulation in the shoot of B-deficient plants suggested that there was some B translocation within the plant. It could be inferred that cotton growth would be impaired by the decrease in carbohydrate translocation rather than by B deficiency in the tissue alone.

On the periodic solutions of the static, spherically symmetric Einstein-Yang-Mills equations

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Existence of Lagrangians for the Yang-Mills equations

The Yang-Mills equations only admit a Lagrangian for gauge groups which are either semisimple or Abelian, or a direct product of groups of both kinds. © 1988.

Manifestly covariant actions for D = 4 self-dual Yang-Mills and D = 10 super-Yang-Mills

Using an infinite number of fields, we construct actions for D = 4 self-dual Yang-Mills with manifest Lorentz invariance and for D = 10 super-Yang-Mills with manifest super-Poincaré invariance. These actions are generalizations of the covariant action for the D = 2 chiral boson which was first studied by McClain, Wu, Yu and Wotzasek.

The significance of root growth on cotton nutrition in an acidic low-P soil

Toxic levels of Al and low availability of Ca have been shown to decrease root growth, which can also be affected by P availability. In the current experiment, initial plant growth and nutrition of cotton (Gossypium hirsutum var. Latifolia) were studied as related to its root growth in response to phosphorus and lime application. The experiment was conducted in Botucatu, Sao Paulo, Brazil, in pots containing a Dark Red Latosol (Acrortox, 20% clay, 72% sand). Lime was applied at 0.56, 1.12 and 1.68 g kg -1 and phosphorus was applied at 50, 100 and 150 mg kg -1. Two cotton (cv. IAC 22) plants were grown per pot for up to 42 days after plant emergence. There was no effect of liming on shoot dry weight, root dry matter yield, root surface and length, but root diameter was decreased with the increase in soil Ca. Shoot dry weight, as well as root length, surface and dry weight were increased with soil P levels up to 83 mg kg -1. Phosphorus concentration in the shoots was increased from 1.6 to 3.0 g kg -1 when soil P was increased from 14 to 34 mg kg -1. No further increases in P concentration were observed with higher P rates. The shoot/root ratio was also increased with P application as well as the amount of nutrients absorbed per unit of root surface. In low soil P soils the transport of the nutrient to the cotton root surface limits P uptake. In this case an increase in root growth rate due to P fertilisation does not compensate for the low P diffusion in the soil.

Cotton growth and boron distribution in the plant as affected by a temporary deficiency of boron

The knowledge of nutrient mobility is an important tool to define the best fertilizer management and diagnosis techniques. Patterns of boron (B) mobility in plants have been reviewed, but there is very little information on B distribution and mobility in cotton. An experiment was conducted to study plant growth and B distribution in cotton when the nutrient was applied in the nutrient solution or to the leaves, and when a temporary deficiency was imposed. Cotton (Gossypium hirsutum, Latifolia, cv. IAC 22) was grown in nutrient solutions where B was omitted or not for 15 days. Boron was applied to young or mature cotton leaves in some of the minus B treatments. Root growth decreased when the plants were transferred to B solutions, but there was a full recovery when B was replaced in the nutrient medium. Boron deficiency, even when temporary, reduced cotton shoot dry matter yields, plant height and flower and fruit set, and these could not be prevented by foliar application of B. Because of decreased dry matter production, leaves of deficient cotton plants actually showed higher B concentrations than non deficient leaves. This would be misleading when a mature leaf is sampled for diagnosis. If there is any B mobility in cotton phloem, it is very low.

Efficacy and total release interval of mating disruption pheromone on the control of pink bollworm - Pectinophora Gossypiella - in cotton under field conditions in Brazil

This experiment was developed in order to evaluation the efficiency of pheromone to control the pink bollworm and the total time of its release in cotton field. The experiment was installed in field conditions, in Chapadao do Sul/SP/Brazil, from January to April, 1998. The treatments consisted of 2 areas, being one of 30ha, where it was applied the pheromone and another of 10ha that was chosen as control area and did not receive pheromone. In the treated area, the laboratory synthesized sex pheromone (PB-Rope) was used thought of dispensers that allowed the slow and gradual release of the active substance. A total of 250 dispenser per hectare were evenly hand distributed in the area. The dispensers were wrapped around the plants. Both areas (treated area and untreated area) were monitored by delta trap. For evaluation of the boll damage, the treatment area was divided into 4 sub-areas. Twenty five green bolls were collected at random from each sub-area at 48 and 65 days after pheromone treatment. Bolls were cracked open by hand, and number of the bolls with symptoms of pink bollworm attacks was recorded. For evaluation of the productivity four areas were demarcated in each treatment, where all fibers and seeds harvested were weighted. Release rate of pheromone from dispenser was evaluated through of the weigh of the dispensers. Were marked and weighed in analytic scale, 20 dispensers contend the pheromone, being placed 10 dispensers under the cotton plants in treated area and other 10 dispensers in an open area. To every 15 days the dispensers were retired and weighed in analytic scale and soon after put back in the field in the same places. The results showed that only one application of mating disrupt pheromone, used in a dosage of 250 dispenser/ha, reached 80% of control for pink bollworm. the release period of pheromone from dispenser, after the application, was 120 days.

Yang-Mills action from open superstring field theory

We calculate the effective action for nonabelian gauge bosons up to quartic order using WZW-like open superstring field theory. After including level zero and level one contributions, we obtain with 75% accuracy the Yang-Mills quartic term. We then prove that the complete effective action reproduces the exact Yang-Mills quartic term by analytically performing a summation over the intermediate massive states. © SISSA/ISAS 2003.

Self-dual super-Yang-Mills as a string theory in (x, θ) space

Different string theories in twistor space have recently been proposed for describing N = 4 super-Yang-Mills. In this paper, a string theory in (x, θ) space is constructed for self-dual N = 4 super-Yang-Mills. It is hoped that these results will be useful for understanding the twistor-string proposals and their possible relation with the pure spinor formalism of the D = 10 superstring. © SISSA/ISAS 2004.

Yang-Mills Chern-Simons corrections from the pure spinor superstring

Nilpotency of the pure spinor BRST operator in a curved background implies superspace equations of motion for the background. By computing one-loop corrections to nilpotency for the heterotic sigma model, the Yang-Mills Chern-Simons corrections to the background are derived. © 2008 SISSA.

Cotton root volume and root dry matter as function of high soil bulk density and soil water stress

Soil compaction reduces root growth, affecting the yield, especially in the Southern Coastal Plain of the USA. Simulations of the root restricting layers in greenhouses are necessary to develop mechanisms which alleviate soil compaction problems. The selection of three distinct bulk densities based on the Standard Proctor Test is also an important factor to determine which bulk density restricts root penetration. This experiment was conducted to evaluate cotton (Gossypium hirsutum L.) root volume and root dry matter as a function of soil bulk density and water stress. Three levels of soil density (1.2, 1.4, and 1.6 g cm-3), and two levels of water content (70 and 90% of field capacity) were used. A completely randomized design with four replicates in a 3×2 factorial pattern was used. The results showed that mechanical impedance affected root volume positively with soil bulk density of 1.2 and 1.6 g cm-3, enhancing root growth (P>0.0064). Soil water content reduced root growth as root and shoot growth was higher at 70% field capacity than that at 90% field capacity. Shoot growth was not affected by the increase in soil bulk density and this result suggests that soil bulk density is not a good indicator for measuring mechanical impedance in some soils.

Semi-selective culture medium for Xanthomonas axonopodis pv. malvacearum detection in cotton seeds (Gossypium hirsutum L.)

The cotton disease known as angular leaf spot, caused by Xanthomonas axonopodis pv. malvacearum (Xam) has been causing cotton losses in several producing regions around the world. Xam is transmitted by seeds, which may be infected both externally and internally. Infected seeds constitute the main long-distance dissemination mode of the pathogen. In view of this, the use of healthy seeds is a must. To accomplish that, detection methodologies for the bacteria must be developed be used in seed health analysis laboratories. This study aimed to develop a semi-selective medium for Xam detection in cotton seeds. The semi-selective culture medium was named MSSXAN and it was consisted of peptone (5.0 g), beef extract (3 g), sucrose (5 g), soluble starch (10 g), agar (15 g), CaCl 2 (0.25 g), Tween 80 (10 mL), distilled water (1,000 mL), crystal violet solution at 1% (150 μL), cephalexin (50 mg 1*), methyl thyophanate (10 mg*) and chlorothalonil (10 mg*) - *added after culture medium autoclaving. This MSSXAN medium shows low repressiveness to Xam and it be used for isolation of this bacteria in cotton seeds health analysis. © 2009 Academic Journals Inc.

Topologically massive yang-mills field on the null-plane: A hamilton-jacobi approach

Non-abelian gauge theories are super-renormalizable in 2+1 dimensions and suffer from infrared divergences. These divergences can be avoided by adding a Chern-Simons term, i.e., building a Topologically Massive Theory. In this sense, we are interested in the study of the Topologically Massive Yang-Mills theory on the Null-Plane. Since this is a gauge theory, we need to analyze its constraint structure which is done with the Hamilton-Jacobi formalism. We are able to find the complete set of Hamiltonian densities, and build the Generalized Brackets of the theory. With the GB we obtain a set of involutive Hamiltonian densities, generators of the evolution of the system. © 2010 American Institute of Physics.

Expression of a new Bacillus thuringiensis Cry1Ia gene in Escherichia coli with strong activity against cotton pests

The control of cotton pests may be accomplished using Bacillus thuringiensis Cry proteins. For this purpose, the objective of this work was to evaluate the insecticidal activity of a new Cry1Ia protein against neonatal larvae of Spodoptera frugiperda and Anthonomus grandis. The complete cry1Ia gene, previously obtained by PCR with oligonucleotide primers based on the sequenced gene, was cloned into the vector pET28a(+), introduced into Escherichia coli BL21(DE3) and expressed by induction with IPTG. The expression of the Cry1Ia protein was confirmed with molecular weight of approximately 81 kDa. The results demonstrated the efficiency of the bacterial system for the expression of B. thuringiensis Cry1Ia protein, which was subsequently used in quantitative bioassays against S. frugiperda and A. grandis larvae, resulting in an extremely toxic protein for both species. This characteristic is exceptionally important for obtaining transgenic cotton plants resistant to these pests.