Crops In USA Research Articles

Assessing Genetic Variability of Pelargonium Species Using PCR-based TRAP Markers

Pelargonium is one of the important flower crops in USA. It is a priority genus for conservation at the USDA Ornamental Plant Germplasm Center (OPGC). It belongs to Geraniaceae family and comprises of about 280 species. To understand the genetic variation of the Pelargonium collection at OPGC, the PCR-based TRAP (target region amplified polymorphism) marker system which was newly developed in sunflower was used in this study. Twelve sets of primers were used to fingerprint 46 accessions representing 21 commercial P. hortorum, 17 scented geraniums and 8 other unidentified Pelargonium taxa. About 150 DNA bands could be detected in each primer and accession combination. Cluster analysis showed that molecular data was highly correlated with the phenotypes. Cultivars with similar morphological traits were clustered together. These results demonstrated that the TRAP system is a useful technique for the characterization and classification of Pelargonium collections.

The influence of two agricultural biostimulants on nitrogen transformations, microbial activity, and plant growth in soil microcosms

The influence of two experimental soil treatments, Z93 and W91, on nitrogen transformations, microbial activity and plant growth was investigated in soil microcosms. These compounds are commercially marketed fermentation products (Agspectrum) that are sold to be added to field soils in small amounts to promote nitrogen and other nutrient uptake by crops in USA. In laboratory microcosm experiments, soils were amended with finely ground alfalfa-leaves or wheat straw, or left unamended, in an attempt to alter patterns of soil nitrogen mineralization and immobilization. Soils were treated in the microcosms with Z93 and W91 at rates equivalent to the recommended field application rates, that range from 0.2 to 1.1 l ha −1, (0.005–0.03 μl g −1 soil). We measured their effects on soil microbial activity (substrate-induced respiration (SIR), dehydrogenase activity (DHA) and acid phosphatase activity (PHOS)), soil nitrogen pools (microbial biomass N, mineral N, dissolved organic N), and transformations (net N mineralization and nitrification, 15N dilution of the mineral N pool, and accumulation of mineral N on ion-exchange resins), and on wheat plant germination and growth (shoot and root biomass, shoot length, N uptake and 15N enrichment of shoot tissues), for up to 56 days after treatment. To follow the movement of nitrogen from inorganic fertilizer into plant biomass we used a 15N isotopic tracer. Most of the soil and plant responses to treatment with Z93 or W91 differed according to the type of organic amendment that was used. Soil treatment with either Z93 or W91 influenced phosphatase activity strongly but did not have much effect on SIR or DHA. Both chemicals altered the rates of decomposition and mineralization of organic materials in the soil, which was evidenced by significant increases in the rates of the decomposition of buried wheat straw, and by the acceleration of net, rates of N mineralization, relative to those of the controls. Soil nitrate availability increased at the end of the experiment in response to both chemical treatments. In alfalfa-amended soils, the final plant biomass was decreased significantly by treatment with W91. Increased plant growth and N-use efficiency in straw-amended soil, resulting from treatments with Z93 or W91, was linked to increased rates of N mineralization from indigenous soil organic materials. This supports the marketing of these compounds as promoters of N uptake at these low dosage inputs.

To Prevent Aridization, Combat Salinity

With some 8% of the world's land-surface occupied by absolute desert, and up to another 40% estimated to be covered or threatened by less-extreme deserts or semideserts, it is clear that still-increasing desertification imposes one of the most critical situations and hence important considerations for the future of Man and Nature. All the inhabited continents are involved to varying degrees, with Australia (80% desertified) the worst-hit areally. And yet the area of the world that is affected by desertification, soil-degradation, erosion, and/or recurrent droughts, continues to increase at a rate of 5–7 million hectares annually in the face of ever-increasing overall human population. This survey warns again of foreseeable dangers for the future.Aridization and more advanced desertification of land result from the combined action of natural tendencies and ecological mistakes made by Man in the course of his manifold activities. Most alarmingly, the velocity of what is mainly anthropogenic aridization is commonly measured in terms of a few years or at most a single human generation. But help should come from the maintenance of rain-fed farming in less arid areas, and especially from the widespread establishment of irrigation systems which now involve some 250 millions of hectares. There are, however, very serious problems engendered by continuing irrigation, which is apt to be wasteful of fresh water. To begin with, river-water resources are becoming increasingly limited and artesian waters are too-easily depleted or become brackish. Worse still, with the high rate of evaporation in arid regions, salinization of the surface and the uppermost soil horizon commonly ensues, and gradually penetrates to lower strata in which plants mainly root. Most existing irrigation systems lack the piping or consistent lining of water-bringing canals and the deep (2.5–3 m) horizontal drainage-ducts that are needed to evacuate excessive soluble salts. The ultimate disposal of the salt, moreover, still causes problems when the sea cannot be used or salt-lakes be created for fish and waterfowl. Meanwhile, revegetation is becoming more and more widely practised and some success is attending efforts to develop salt-resistant crops in USA, India, and USSR.