Browsing by Subject "Hydroponics"
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Item A Hydroponic Approach to Evaluate Salt Tolerance in Cotton(2011-08) Castillo, Natalia; Auld, Dick L.; Dever, Jane G. K.; Abidi, Noureddine; Burke, John J.; Zhang, HongInterests in developing salt tolerant cultivars have intensified as the result of an increasing population and environmental constraints that limit crop productivity. New agronomic models have been designed to address the new challenges. Some include the development of a salt tolerant crop by evaluation and selection of tolerant germplasm, hybridization with selected germplasm, and development of inbred lines through pedigree selection or backcross, and testing of selected inbred lines. Many wild accessions in cotton have been found in many areas in the world and made accessible for research. Plant breeders are trying to produce new cotton varieties that can withstand the excessive salt concentrations found in the soil and in the water since salinity has become a limiting factor in crop agriculture. For farmers the abiotic stress due to salinity limits yield by inhibiting germination, flowering, and the development of vegetative branches and fruiting branches. Other concerns of plant breeders are abscission of cotton bolls, a reduction in cellulose deposition, and that both photosynthesis and stoma conductance are affected during the breakdown and conversion into carbohydrates. Preliminary studies conducted in 2006, 2007, 2008, and 2009 show one wild accession, TX 307 to be significantly more tolerant than others when plants were treated with NaCl. Since 2010, the focus of this research has been to use the hydroponic system as a screening method to evaluate and compare responses among cotton genotypes for salt tolerance characteristics to salinity stress. The wild cotton accession TX 307 was used as a control line to compare to three commercial cultivars ‘FM 989’ (PI603956, PVP9800259), ‘DP 491’ (PI618609, PVP 200100159, US2003/0229928AI), and ‘Coker 312’ (PI529278, PVP7200100); and two transgenic lines Avp68 and Avp86. Coker 312 was the cultivar used for the transformation and regeneration of Avp68 and Avp86 transgenic lines. Responses were evaluated at different salt concentrations (dose response) and at the same concentrations over time. The study was conducted under greenhouse conditions at the AgriLife Research and Extension Center in Lubbock, Texas. Experimental design was a randomized split block with four replications, four treatments, and ten plants/treatment sampling error. Significant differences (p < 0.05) were found during the dose response screening study, however, no significant response genotype interactions over time was observed. The hydroponic system was perhaps not the best method for evaluating response differences at later plant development stages because of possible premature plant death, but it was an effective screening method to isolate individual plants with respect to morphological and physiological responses to salinity stress. The system could also be used as an assessment tool to identify contrasting phenotypes at high salt concentrations early in plant development.Item Composition and flavonoid levels in onions (Allium cepa) grown in hydroponics in greenhouses and growth chambers(Texas Tech University, 2001-12) Morris, Jay L.One-thousand eighty long-day onions (Allium cepa L. 'Purplette') grown ' hydroponically in a greenhouse were analyzed for composition and total edible biomass to determine the amount of variability as the plant matures. Plants were harvested at 14, 21, 28, 35, 42, 49, 63, 77 and 98 d after sowing. Plant height increased as plants aged, and a significant interaction between planting date and plant age was noted. Plant weight and net number of leaves increased with age and again an interaction between age and planting date was observed. Percent N decreased from 0.55-.34% (p < 0.05) as the plants aged. Percent C (C) decreased (p < 0.05) as the plants aged but after d 77 a significant increase occurred. Ash content increased (p < 0.05) as the plant aged, with means ranging from 0.09 -1.07%. Calcium (Ca) and magnesium (Mg) concentration decreased (p < 0.05) as the plant aged with means rangmg from 128.7 - 14.2 mg/100 g and 57.1 - 22.0 mg/100 g, respectively. Potassium (K) concentrations showed an interaction (p < 0.05) between age and plant age. Total flavonol (TF) content increased (p < 0.05) from 226.1 - 554.7 mg/100g, as the plant aged from 14 d to 98 d. Dry matter (DM) content and sulfur (S)concentration was unchanged (p > 0.05) as the plant aged. Mean values ranged from 10.47-10.70% and 185.2-193.6 mg/100 g for dry matter content and S concentration, respectively. Biomass production and proximate composition of onions varied significantly as the plant ages and underwent morphological changes.Item Influence of nutrient solution and solution pH on onion growth and mineral content(Texas Tech University, 2003-08) Kane, Chad DThis study is a component of a project designed to develop a management strategy for growing onions in a closed growth system on a vehicular space setting. The objective of this research was to evaluate the effects of hydroponic nutrient solution and solution pH on growth and mineral content of green onions. Three onion varieties, Allium cepa L. ('Deep Purple' and 'Purplette') and A. fistulosum L. ('Kinka'), were propagated in three nutrient solutions (Peter's Hydro-Sol, Hoagland's, or half strength Hoagland's), at two pH levels (5.8 and 6.5), in a three by two factorial design applied in a randomized block with three replications. Seeds were germinated in Cropking's Oasis Horticubes™ under greenhouse conditions, and were irrigated with tap water. Once the seedlings reached the flag stage, the plants were placed into hydroponic units within the greenhouse and grown under ambient conditions. Plants were harvested 30 days after transplanting to the hydroponic units. Based on efficient plant growth, the half strength Hoagland's solution is the preferred nutrient solution evaluated in this research. However, Hydro-Sol generally produced onions with highest the mineral content. Mineral content varied with plant part,nutrient, nutrient solution, solution pH, and onion variety. Selection of an appropriate nutrient solution must consider both edible biomass production and mineral content. In the research reported here the solution that produced the greatest biomass did not produce plant material with the mineral content. Future research may lead to the development of a modified nutrient solution that optimizes both edible biomass production and mineral content