Browsing by Subject "Cotton -- Growth"
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Item Characterization of intraspecific and interspecific populations of cotton and common cocklebur grown under two water regimes(Texas Tech University, 1985-12) Wells, Jerry WayneNot availableItem Cotton Development and Yield as Affected by Insecticides(Texas Tech University, 1984-05) Lloyd, Randy WNot Available.Item Growth and development of cotton when released from osmotic stress(Texas Tech University, 1980-08) Prien, Samuel D.Not availableItem Phosphorus and Potassium Effects on the Emergence, Growth, and Resultant Seed Quality of Cotton(Texas Tech University, 1985-05) Hicks, Thomas VintNot Available.Item Relationship between observations in mini-rhizotrons and true root length density(Texas Tech University, 1985-08) Upchurch, Dan RoyceThis project has resulted in the development of two models which can be applied to the mini-rhizotron technique for root observations. The models are based on probabilistic assumptions concerning root growth directions in the soil. The models apply to the average number of roots which intersect the wall of several tubes buried in the soil, and not to individual observation tubes. The usefulness of the mini-rhizotron technique has been expanded to include indications of the orientation of the root system through the ratio hypothesis. The conversion of root counts to root length density (RLD) has been given a mathematical basis, with few assumptions. The primary disadvantage of the system is the number of samples required. By determining the ratio of the number of roots which intersect the top to the number which intersect the bottom, the model predicts the direction of deviation from a random orientation. Observations made on the wall of a trench confirmed the horizontal orientation of a cotton root system and the existence of upward growth which had been predicted by the model from observations in mini-rhizotrons. A model, relating the number of root intersections on a mini-rhizotron to the bulk soil RLD, predicted a linear relationship. The average length to associate with each intersection was determined assuming that root growth was affected only after an intersection occurred, that roots can be represented by straight line segments, and that root growth direction followed some probability density function. The assumption that roots can be represented by straight lines can be removed if the tortuousity of the path of root growth is known. The length can be weighted by the probability of root growth in that direction, if it is known. The correlation coefficient between RLD determined by applying the model to mini-rhizotron observations and that from soil cores was low but significant at the 99% level, when all treatments and angles were considered. The correlation was largest, 0.70, in the dryland treatment at the 30 installation angle. The higher correlation in the dryland treatment may have resulted from of the reestablishment of the natural soil structure at the interface as the soil dried. The statistical properties of the mini-rhizotron system emphasize the need for a large sample size. The number of samples required to detect specific differences in RLD is large for both soil cores and mini-rhizotrons when the difference is small. The decision about the number of tubes to install will be affected by the reported variance, the magnitude of the expected RLD, the difference in RLD which is important to the project, and the resources of the project. The variance of the mini-rhizotron was larger than soil cores in this project, but in another project reported in the literature this result was reversed.Item Relative contribution of assimilates and turgor pressure to leaf area development(Texas Tech University, 1981-05) Yimbo, Peter OriwaNot availableItem Somatic embryogenesis and plant regeneration in Gossypium hirsutum L.(Texas Tech University, 1985-12) Trolinder, Norma L GloverRegeneration of Gossypium hirsutum L. has been a much sought-after goal that would make feasible the use of somaclonal variation and gene manipulation for improvement of existing breeding lines. This study delineates a protocol for consistently regenerating G. hirsutum cv Coker 312. Optimal media for induction of somatic embryogenesis from mature and immature tissues of G. hirsutum L. cv Coker 312 has been determined. Explants of three-day seedlings form somatic embryos in 100% of cultures when treated with 0.1 mg/1 2,4-dichlorophenoxy acetic acid plus 0.5 mg/1 kinetin. The apical region of the seedling also responds 100% to 0.5 mg/1 napthaleneacetic acid plus 0.5 mg/1 kinetin. Mature tissues are more recalcitrant, forming somatic embryos on a limited number of treatments. Stem tissue is most readily induced by 2 mg/1 napthaleneacetic acid plus 0.1 mg/1 kinetin, whereas leaf tissue responds efficiently to 0.1 mg/1 2,4-dichlorophenoxy acetic acid plus 1.0 mg/1 2 iso-pentyl adenine or 1.0 mg/1 napthaleneacetic acid plus 0.5 mg/1 2 iso-pentyl adenine. Embryogenic cell suspensions have been established and maintained by serial subculture in Murashige and Skoog basal medium (MS). Globular embryos develop normally when plated on solid medium containing basal MS medium. If subcultured to liquid MS basal medium in total darkness, globular embryos complete development, although cotyledons are less expanded and more vitreous than those on solid medium. A critical density of cells is required for embryo development in cell suspension. Addition of equimolar concentrations (10- 7M ) of abscisic acid, gibberellic acid, and kinetin enhances globular embryo proliferation, but normal development is suppressed. Glutamine enhances both embryo proliferation and development. Light plays a major role regardless of medium supplement. In general, less browning of tissue and more normal cotyledon growth occurs in complete darkness; however, greater proliferation is observed in some cultures when an 18/6 hour photoperiod is provided. Embryo germination and plant development is best accomplished on vermiculite saturated with Beasley-Ting (BT) medium supplemented with 500 mg/1 casein hydrolysate. Regenerated plants are conditioned in either a one to one mix of peat and sand or vermiculite by placing glass beakers over new plants and gradually increasing the size of the beakers from 10 ml to 150 ml as the plants grow.