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Evaluation of a Metabolic Cotton Seedling Emergence Model

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American Journal of Plant Sciences 2015年第11期6卷 1727-1733页

作者： Dennis C. gitz III Jeffrey t. Baker James R. Mahan Cropping Systems Research Laboratory United States Department of Agriculture* Lubbock USA

A model for cotton seedling emergence (MaGi) based on malate synthase kinetics was evaluated. Cotton seeds were planted through the early spring and into typical planting times for the areas. Soil temperatures at seed depth were used as inputs into MaGi and a commonly used seedling emergence model based on heat unit accumulation (DD60). time to 50% emergence was calculated and compared with predicted emergence using MaGi and DD60. MaGi yielded predictive capability without the need to resort to lengthy experimentation required by traditional methods. the results suggest that a physiological or semi-empirical approach incorporating both enzyme kinetics and whole plant temperature responses would be useful for rapidly constructing seedling emergence models.

关键词： Cotton Seed Emergence Degree Day Crop Model

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

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

Scaling Leaf Measurements to Estimate Whole Canopy Gas Exchanges of Cotton

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American Journal of Plant Sciences 2016年第14期7卷 1952-1963页

作者： Dennis C. gitz III Jeffrey t. Baker Robert J. Lascano Wind Erosion and Water Conservation Unit Cropping Systems Research Laboratory USDA-ARS1 Lubbock TX USA

Diurnal leaf and canopy gas exchanges of well-watered field grown cotton were measured. Our objective was to scale leaf-level values of transpiration and net assimilation to the whole canopy level using estimates of canopy leaf area. Single leaf gas exchange measurements were made with two portable photosynthesis systems and canopy measurements with four open Canopy Evapo-transpiration and Assimilation (CEtA) chamber systems. Canopy leaf area was measured at the end of the experiment and estimated during gas exchange by fitting values to a growth curve. Leaf level measurements were arithmetically scaled to estimate canopy level gas exchange based on canopy leaf area and then compared to the measured values. Scaled values of single leaf transpiration were very similar to canopy transpiration measurements, although both whole canopy transpiration and assimilation were overestimated around mid-day. We conclude that canopy cotton transpiration of well-watered field grown plants could be estimated within 5% throughout the day by scaling leaf level measurements to the whole canopy using measured canopy leaf area. Estimating canopy assimilation from leaf level measurements remains problematic.

关键词： Cotton Gossypium hirsutum Scaling Assimilation transpiration Drought Stress

the Stem Heat Balance Method to Measure transpiration: Evaluation of a New Sensor

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Agricultural Sciences 2016年第9期7卷 604-620页

作者： Robert J. Lascano timothy S. Goebel Jill Booker Jeffrey t. Baker Dennis C. gitz III USDA-ARS Wind Erosion and Water Conservation Research Unit Plant Stress and Water Conservation Laboratory Lubbock TX USA USDA-ARS Wind Erosion and Water Conservation Research Unit Plant Stress and Water Conservation Laboratory Big Spring TX USA

the measurement of crop transpiration (tcrop) under field conditions and throughout the growing season is difficult to obtain. An available method uses stem flow gauge sensors, based on the conservation of energy and mass, where the calculated sap flow (F) is a direct measure of tcrop. this method has been extensively tested on agronomic, horticultural, ornamental aspects and tree crops and the general consensus is that F is a measure of tcrop. A new sap flow gauge (EXO-SkintM Sap Flow) sensor, with different placement and number of thermocouples, compared to the original sensor, was introduced, resulting in a different energy balance equation to calculate F. Our objective was to compare values of tcrop obtained with the new sensor on cotton (Gossypium hirsutum, L) plants to values measured with lysimeters. For this purpose, cotton plants were grown in 11-liter pots in a greenhouse experiment and hourly and daily values of tcrop were compared for eight days. We used linear regression analysis to compare the hourly and daily values of tcrop measured with the sensor to corresponding values measured with lysimeters on the same plant. Using a t-test (p > 0.05) we tested if the slope of the line was significantly different than 1 and if the intercept was significantly different than 0. this test indicated that there were no statistical differences between hourly and daily values of tcrop measured with the new sensor and with the lysimeters. the main advantage of the new sensor is the flexibility of the new heater, allowing for better thermal contact between the plant stem and the temperature sensors. Further, the new sensor requires less wiring and copper connectors, and the number of channels used in a datalogger to record the output from the sensor is reduced by 25%. We conclude that the new sensor correctly measures tcrop and that additional experiments with field grown plants are required to test the sensor at hig

关键词： Cotton Greenhouse Irrigation Evaporation Water Use Water Management

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

the Microenvironment within and Pollen transmission through Polyethylene Sorghum Pollination Bags

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American Journal of Plant Sciences 2015年第2期6卷 265-274页

作者： Dennis C. gitz Jeffrey t. Baker Zhanguo Xin John J. Burke Robert J. Lascano United States Department of Agriculture-Agricultural Research Service# Wind Erosion and Water Conservation Unit Lubbock Texas USA United States Department of Agriculture-Agricultural Research Service Wind Erosion and Water Conservation Unit Big Spring Texas USA United States Department of Agriculture-Agricultural Research Service Plant Stress and Germplasm Development Unit Lubbock Texas USA

Bird damage is a problem in sorghum breeding and germplasm maintenance operations. Paper pollination bags are damaged by rain and provide minimal deterrent to birds. Earlier we reported upon bird resistance of spun polyethylene pollination bags. Herein, we report the potential for pollen transmission through, and the microenvironment within, hard form (Hft) and soft form (Sft) spun polyethylene pollination bags as compared to traditional Paper pollination bags. Within Paper pollination bags morning temperatures were 10°C - 15°C above ambient and high temperature excursions as high as 45°C were measured. Heating in Sft and Hft was 25% and 50% that of Paper, respectively. temperature differences between bags were attributed to differences in albedo and air permeability of the bag materials. No difference in pollen transmission through Paper and Hft was found. Although Sft allowed 35% - 40% wind borne pollen through the pores as compared to controls, male sterile plants covered with Sft produced only 30 seeds/panicle, about 1% of a self-pollinating fertile plant. Our results suggested that Sft could adequately reduce or eliminate cross-pollination in self-pollinating plants while maintaining near ambient environmental conditions.

关键词： Sorghum Breeding Pollination Bags Bird Damage

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

Systematic Errors Introduced into Sorghum Grain Yield Data: Does the Multiseed (<i>msd</i>) trait Increase Sorghum Seed Yield?

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American Journal of Plant Sciences 2019年第9期10卷 1503-1516页

作者： Dennis C. gitz III Jeffrey t. Baker Zhanguo Xin John E. Stout Robert J. Lascano USDA-Agricultural Research Service1 Cropping Systems Research Laboratory Lubbock TX USA

Multiseed (msd) mutant sorghum [Sorghum bicolor (L.) Moench] lines with greatly increased seed numbers were developed. It was originally thought that the msd trait could increase grain yield several times in comparison with the wild type from which the mutant was derived. However, in a small plot trial, msd seed yield decreased when compared to the parent line. Herein we report results that msd seed yield remained either unchanged or slightly increased in comparison to the parent line. We suggest that attempts to measure msd sorghum seed yield were complicated due to systematic errors associated with the post-harvest processing methods, including threshing and pneumatic winnowing equipment that was used for harvest. that is, seed recovery and seed loss from individual panicles were affected by the post-harvest processing. When evaluating sorghum grain yield of types with different seed sizes, threshing and seed cleaning harvesting methods should be optimized for each sorghum line.

关键词： Sorghum Yield Yield Components msd Multiseed Yield Measurement Error