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Short Communication: Analysis of Grain Size Distribution through Image Analysis

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American Journal of Plant Sciences 2018年第12期9卷 2339-2346页

作者： Dennis C. Gitz III Jeffrey T. Baker Paxton Payton Zhanguo Xin Robert J. Lascano usda-ars Cropping Systems Research Laboratory Lubbock TX USA

Herein we describe an approach to measure the volume and to characterize the volume distribution of large numbers of individual small regularly shaped seeds. The results of a preliminary investigation into the distribution of seed size of a multi-seeded sorghum mutant, as compared to the wild type from which it was developed are also reported, and are used as an example of the method’s utility.

关键词： Seed Size Grain Size Sorghum Twin Seed Multi-Seed Image Analysis

CO2 and Chamber Effects on Epidermal Development in Field-Grown Peanut (Arachis hypogaeaL.)

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American Journal of Plant Sciences 2017年第3期8卷 349-362页

作者： D. C. Gitz III J. T. Baker H. Echevarria-Laza P. Payton J. R. Mahan R. J. Lascano cropping systems research laboratory ARS-USDA Lubbock TX USA

Peanut, (Arachis hypogaea L.) cvar. C76-16, was grown either in the field, or in open gas exchange chambers under elevated or ambient CO2 concentrations. Stomatal density and other selected epidermal parameters associated with leaf development and gas exchange were measured on recently fully expanded canopy leaves. It was hypothesized that exclusion of solar UV by chambers would affect stomatal density, but no clear statistically significant chamber effect on stomatal density was found. However, elevated [CO2] did lead to a reduction in both adaxial and abaxial stomatal developmental initiation and in stomatal density. Since each stomate was bounded by companion cells resulting from developmental events, non-random stomatal spacing as the “one cell spacing rule” appears to result from ontogeny rather than a long hypothesized chemical signal inhibiting adjacent meristemoid differentiation into guard cells. A method of visualizing epidermal patterns is also described.

关键词： Peanut Stoma Stomatal Density Carbon Dioxide Climate Change

Relating Xylem Cavitation to Gas Exchange in Cotton

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American Journal of Plant Sciences 2015年第11期6卷 1742-1751页

作者： Dennis C. Gitz III Jeffrey T. Baker Robert J. Lascano cropping systems research laboratory USDA-ARS# Lubbock USA

Acoustic emissions (AEs) from xylem cavitation events are characteristic of transpiration processes. Though a body of work exists describing AEs and limited stem hydraulic conductivity under water stress, there is limited information about the effects of AEs on stomatal aperture and limitation on carbon assimilation. The objective of this work was to relate AEs to drought stress in cotton. Cotton was grown in mini-lysimeters in the greenhouse and instrumented with a portable photosynthesis system and ultrasonic transducers connected to a digital signal-processing unit. Whole plant transpiration, leaf level gas exchange and ultrasonic AEs were measured. Xylem cavitation events temporally associated with the onset of drought stress. The results are consistent with stomatal closure in response to reduced hydraulic conductance from xylem cavitation events. Clear direct empirical evidence of a reduction in carbon assimilation associated with xylem cavitation resulting from water stress is presented.

关键词： Xylem Cavitation Drought Stress Stomatal Control Irrigation Scheduling

Genetic Diversity in the Environmental Conditioning of Gossypium hirsutumand Gossypium barbadenseCultivars

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American Journal of Plant Sciences 2017年第3期8卷 517-532页

作者： John J. Burke usda-ars PA Cropping Systems Research Laboratory Lubbock TX USA

Enzyme adaptations to temperature occur constantly as temperature patterns modulate diurnally and seasonally. These adaptations entail qualitative and/or quantitative metabolic changes that often provide a competitive advantage, impact adjustment to new environments, and effect the survival of the species. Changes in isozymes or allozymes, changes in enzyme concentration, modification by substrate and effectors, and metabolic regulation of enzyme function without changing enzyme composition are all possible strategies for adaptation to changes in temperature. The degree of adaptation among cotton cultivars to a specific thermal regime may be difficult to determine from phenotypic responses of the plants. The present study evaluated the thermal sensitivity of Gossypium hirsutum L. and Gossypium barbadense L. cultivars following growth under distinct thermal environments. The metabolic fitness of Gossypium hirsutum L. and Gossypium barbadense L. cultivars showed that the Gossypium hirsutum L. cultivars grown in a 28°C/20°C day/night cycle tended to be better equipped to cope with a 16 h - 38°C treatment than the same cultivars grown in a 38°C/32°C day/night cycle. The Gossypium barbadense L. cultivars, on the other hand, grown in a 38°C/32°C day/night cycle tended to be equipped to cope with a 16 h - 38°C treatment than the same cultivars grown in a 28°C/20°C day/night cycle. The Gossypium hirsutum L. line TX 303 is an exception to these general trends as its responses were similar to the Gossypium barbadense L. St. Vincent and Pima S-7 cottons.

关键词： Cotton Gossypium hirsutum L. Gossypium barbadense L. Thermal Sensitivity Adaptation

Stable Carbon Isotope Discrimination (δ¹³C) of Cotton Burrs and Seeds as a Season-Long Integrator of Crop Water Stress

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American Journal of Plant Sciences 2022年第12期13卷 1448-1459页

作者： Dennis C. Gitz III Jeffrey T. Baker Robert J. Lascano cropping systems research laboratory ARS-USDA1 Lubbock USA

Plant-based irrigation management schemes typically use surrogates such as canopy temperature, alone, or in conjunction with environmental variables, to infer the degree of “crop stress” (biological strain) induced by drought. Few systematic studies of the relationship between “crop stress”, as defined by such surrogates, and physiological estimates of water use efficiency (WUE) exist over both daily and seasonal time scales relevant to agronomic irrigation control. The systematic application of stable carbon isotope discrimination (δ13C) might allow post hoc evaluation of irrigation scheduling schemes and might also be a useful germplasm screening tool if the source(s) of variability can be uncovered and/or controlled. Results from preliminary efforts comparing leaf and cotton seed δ13C to season-long water deficits showed that seeds are more useful indicators of season-long water stress and water use efficiency during crop development.

关键词： Irrigation-Scheduling Germplasm Screen Water Management

Canopy Light Interception of a Conventional and an Erect Leafed Sorghum

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American Journal of Plant Sciences 2015年第16期6卷 2576-2584页

作者： Dennis C. Gitz III Zhanguo Xin Jeffrey T. Baker Robert J. Lascano John J. Burke cropping systems research laboratory USDA-ARS# Lubbock TX USA

Two sorghum lines, an erect leafed mutant sorghum and the wild type from which the mutant was generated, were field grown in rectilinear arrays at low (10 plants m-2) and high (23 plants m-2) population densities. Canopy light interception, biomass accretion and yield were measured. Photosynthetically active radiation under the canopy at ground level and midway through the canopy were higher in the erect leafed line, as compared to the normal leafed line. Planting density had less effect on mean grain yield and biomass in the erect leaf line than in the wild type. Though not conclusive, when taken together, the results suggested that optimal planting densities are higher for the erect leaf line and that the erect leaf trait could be useful for incorporation into breeding programs.

关键词： Sorghum Erectophile Mutant Erect Leaf

Genetic Diversity in the Environmental Conditioning of Two Sorghum (Sorghum bicolorL.) Hybrids

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American Journal of Plant Sciences 2018年第4期9卷 817-831页

作者： John J. Burke Yves Emendack Chad Hayes Junping Chen usda-ars PA Cropping Systems Research Laboratory Lubbock TX USA

Sorghum metabolism continually adapts to environmental temperature as thermal patterns modulate diurnally and seasonally. The degree of adaptation to any given temperature may be difficult to determine from phenotypic responses of the plants. The present study was designed to see if the efficiency of quantum yield of photosystem II could be used as a measure of how well leaf tissue metabolism was able to withstand a prolonged respiratory demand caused by elevated temperatures. The efficiency of quantum yield values of Pioneer 84G62 and Northrup King KS585 commercial sorghum hybrids showed that when the hybrids were grown in a 28°C/20°C day/night cycle in the greenhouse or the field, Pioneer hybrid 84G62 withstood subsequent elevated thermal challenges better than Northrup King KS585. The same hybrids grown in a 39°C/32°C day/night cycle showed similar efficiency of quantum yield values when thermally challenged. Water-deficit stress increased the heat resistance of the tissue raising the efficiency of quantum yield of both lines to the same level. Upon recovery from the water deficit stress the differential efficiency of quantum yield values between the two lines re-appeared. The data provided in this study suggest a metabolic advantage of Pioneer 84G62 to environmental thermal challenges compared with the Northrup King KS585.

关键词： Sorghum Sorghum bicolor L. Thermal Sensitivity Adaptation

Measurement of Cotton Transpiration

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Agricultural Sciences 2018年第10期9卷 1299-1316页

作者： Robert J. Lascano Jeffery T. Baker Paxton Payton Dennis C. Gitz III James R. Mahan Timothy S. Goebel Wind Erosion and Water Conservation research Cropping Systems Research Laboratory USDA-ARS Lubbock TX USA Plant Stress Germplasm Development research Cropping Systems Research Laboratory USDA-ARS Lubbock TX USA

There are a few field methods available to directly measure water evapotranspiration (ET) along with its two components, evaporation from the soil (E) and from the crop (T). One such technique that measures T, uses sensors to calculate the sap flow (F) of water through the plant stem and is based on the conservation of mass and energy, i.e., the stem heat balance method. This instrument consists of a flexible heater that is wrapped around the plant stem with temperature sensors to measure the difference in temperature of F below and above the heater. This is a null method, where all inputs and outputs are known and the calculated F is a direct measure of T. This method has been used to measure T in a variety of crops, including cotton, grapes, olive trees, soybean, ornamental and horticultural crops. A new version of the EXO-SkinTM is the Stem Gauge Dual Channel Design (SGDCTM), which was commercially introduced and had a radically new design resulting in a different energy balance, compared to the original design, which needed experimental verification. An initial evaluation was done with potted cotton (Gossypium hirsutum, L.) plants in a greenhouse experiment showing that values of cotton-T measured with the new sensor were accurate;however, this comparison was limited to daily T T in the 2 - 7 mm/d range, representative of the semiarid Texas High Plains. For this purpose, cotton was planted on 12 June 2017 on a 1000 m2 plot in a soil classified in the Amarillo series at the facilities of the usda-ars, Lubbock, TX. For a period of 15 days, 2 to 16 Sep 2017, we measured hourly cotton-T with the new sensors and with portable growth chambers (0.75 m × 1 m cross-section, and 1 m height) where water vapor flux was measured at a 10 Hz frequency using an infrared gas analyzer. We used three chambers and, in each chamber, the new sensors were installed on four cotton plants. We used linear regression analysis to compare hourly and daily values of cotton-T measured with th

关键词： Stem Flow Gauge Growth Chamber Water Use Irrigation Evaporation Field Test

Description of a Novel Allelic “Thick Leafed” Mutant of Sorghum

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American Journal of Plant Sciences 2017年第12期8卷 2956-2965页

作者： Dennis C. Gitz III Lan Liu-Gitz Zhanguo Xin Jeffrey T. Baker Paxton Payton Robert J. Lascano cropping systems research laboratory ARS-USDA1 Lubbock TX USA

An allelic sorghum [Sorghum bicolor (L.) Moench] mutant with thick and narrow erect leaves (Thl) and reduced adaxial stomatal density was isolated from the Annotated Individually pedigreed Mutagenized Sorghum mutant library developed at the Plant Stress and Germplasm Development Unit at Lubbock TX. The mutant, Thl, was isolated from a pedigreed M3 family generated by ethyl methanesulfonate mutagenization from an elite inbred sorghum line, BTx623, which had been used to sequence the sorghum genome. The mutant has been backcrossed to the wild-type BTx623 confirming that the trait results derive from a stable recessive nuclear gene mutation. Herein, we briefly described morphological and selected physiological characteristics of this mutant sorghum.

关键词： Sorghum Stoma Stomatal Density Stomatal Ratio Leaf Thickness