Barley selection

Figure 3 Root fingerprints of Pseudomimets sp. associated with barley seedlings showing the production of siderophore by actively growing bacteria located in the zone of elongation behind the root tips. Root.s were pressed on to an iron-deficient minimal medium selective for Pseudomonas. After growth of the colonies, the production of siderophore was visualized by exposure of the agar plate to ultraviolet light, which causes the siderophore to Huoresce.

Diphenyl ethers are both systemic and contact herbicides and are used for the selective control of annual broad-leaved weeds and grasses in a variety of crops (such as soybeans, maize, rice, wheat, barley, peanuts, cotton, onions and ornamental trees) under different application scenarios. This class of herbicides contains a diphenyl ether moiety as the core substructure. Acifluorfen, bifnox, chlomethoxyfen, chlorni-trofen, fluoroglycofen-ethyl and fomesafen, etc., are representative compounds of the diphenyl ether herbicides (Figure 1). 

Although the compounds described above were non-selective herbicides and aromatic substitution resulted in compounds of lower activity, it was gratifying to find that the mixture, coded AC 222,293, and prepared as shown in Scheme I, had good activity against wild oats, black grass and mustards yet was well tolerated by most winter and spring wheats and barleys. 

The aim of the present study was to find whether differences could be detected in the compositions of mixture of volatile compounds sampled from the root zone of two different cultivars of barley. To have a reasonable base for a relevant genetic variation in the plant material, two cultivars with different adaptation to acid soils were selected. The sampling was done from young plants, as the establishment of the rhizosphere microflora is of importance in early stages of plant development. 

DDT was not the only synthetic chemical to find a use in private and commercial gardens. Plant physiologists in the 1930s had accidentally discovered a way of selectively killing weeds in cereal crops (the dominant source of food for humans— wheat, barley, maize and rice). The plant physiologists interested in how plants controlled their growth had discovered a plant hormone—auxin (indole-3-acetic acid). Chemists soon found that, not only was it easy to make this compound, but they could also easily make... 

Resistance to insects has been successfully selected and introduced into important cultivars of a number of plant species including potatoes, wheat, corn, grapes, alfalfa, barley, beans sorghum, rice and sugar cane (25). This resistance is usually due to a combination of factors and only in a few cases is a single chemical factor identifiable as responsible for resistance (32). 

Contamination occurs primarily in wheat, barley, rye, and maize. Type A trichothecenes include mainly T-2 toxin, HT-2, and diacetoxyscirpenol (DAS) mycotoxins of the group B include mainly 4-deoxynivalenol (DON), commonly known as vomitoxin, and nivalenol (NIV). Toxic effects include nausea, vomiting, visual disorder, vertigo, throat irritation, and feed refusal in farm animals. The most toxic is T-2, followed by DAS and NIV, with DON being the least toxic in acute toxicity studies but the most widespread in grains worldwide and therefore the most studied. Issues related to chemical and physical data, occurrence, toxicity, absorption, distribution, and metabolism of trichothecenes are reviewed in WHO (89) and IARC (34). Physicochemical data for some selected Fusarium toxins is given by Sydenham et al. (90). The molecular structures of the main trichothecenes are shown in Fig. 9. 

The carboxin is extracted from the sample with acetone in a Soxhlet extraction apparatus and, after concentration of the extract, is determined via gas-liquid chromatography using a nitrogen-selective detector. The presence of carboxin is confirmed by the use of a sulfur flame photometric detector. Recoveries ranged from 73 to 80% (barley) and 73 to 78% (wheat). 

Uses pre-emergent and selective herbicide to control wild oats and blackgrass in barley, corn, flax, lentils, peas, potatoes, soybeans, and sugar beets. 

Seeds of lettuce (Lactuca sativa L. cv. Roman), cress (Lepidium sativum L. cv. Comun), and onion (Allium cepa L. cv. Valenciana), were obtained from FITO, S.L. (Barcelona, Spain). Seeds of wheat and barley (Hordeum vulgare L) were obtained from Rancho La Merced, Junta de Andalucia, Jerez, Spain. All undersized or damaged seeds were discarded, and the assay seeds were selected for uniformity. Bioassays were carried out in 9 cm 0 plastic Petri dishes, using Whatman 1 filter paper as support. 

D, introduced by Amchem in 1945, was the first of a series of phenoxyacetic acid herbicides (Fig. 3). These compounds are highly effective herbicides that selectively kill broadleaf weeds with little or no damage to grasses. They are still widely used to control broadleaf weeds in corn, wheat, barley, sorghum, sugarcane, grass pastures, and in turf. 

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