Location: Crop Production Systems Research
Project Number: 6066-22000-095-002-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Jun 27, 2022
End Date: May 31, 2027
Objective:
We hypothesize that there will be winners and losers in crop species with climate change in terms of water use, growth and yield, and yield quality. We also hypothesize that physiological, above- and belowground related traits in crop species would have different temperature and soil moisture thresholds, and elevated atmospheric CO2 will modify those responses and thresholds. In addition, changing the intensities of environmental stresses, including elevated CO2 will affect the seed and grain quality and nutritive values of major crops. The overarching goal of this project is to understand how changing climate factors (temperature, drought, and atmospheric carbon dioxide) affect crop species growth and development during their juvenile and grain-filling stages. We will conduct a series of experiments with varying temperatures and drought salt stress intensities with current and projected changes in atmospheric carbon dioxide using our internationally reputed sunlit plant growth chambers known as Soil-Plant-Atmosphere-Research (SPAR, WWW.spar.msstate.edu) at Mississippi State.
Year 1: The specific objectives of this study will be to investigate the effect of soil moisture stress during the reproductive stage growth and development, photosynthesis and water use, seed protein, oil, fatty acids, sugars, and macro-and micro-nutrients in two soybean cultivars with distinct tolerance to drought and temperature and to provide soil moisture-seed quality functional algorithms that could be used to develop new modules in soybean crop models.
Year 2: The objectives of a second study will be to quantify the effect of gradient temperatures on gas exchange parameters, quantify temperature effects on transpiration and water-use, quantify the temperature effects on yield components of two soybean or corn hybrids, to determine the effect of temperatures on the transgenerational seed germination and to provide quantitative information that could be useful to improve the functionality of crop models for field applications.
Approach:
An experiment will be conducted at the Rodney Foil Plant Science Research facility of Mississippi State University, Mississippi State, Mississippi, utilizing sunlit environmental growth chambers. Initially, seeds from two soybean cultivars will be grown in large pots (15.2 cm diameter by 30.5 cm high) outdoors filled with 3:1 sand: top topsoil is classified as a sandy loam (87% sand, 2% clay, and 11% silt). Plants will be irrigated with full-strength Hoagland’s nutrient solution from the beginning. Inside the chambers, pots will be organized in a completely randomized design with nine replications per cultivar arranged in 6 rows with two pots per row. More details of the arrangement of the pots and the treatments have previously been described by Wijewardana et al. (2018). The treatments included five levels of irrigation, 100, 80, 60, 40, and 20%, which will be maintained, based on percent evapotranspiration (ET) values recorded on the previous day. Treatments will be imposed at flowering and will be continued until harvests. Initially, all plants will be irrigated with the same water volume as in the 100% ET treatment until the time that each treatment is imposed. The ET measured will be on a ground area basis (L d-1) throughout the treatment period as the rate at which condensate will be removed by the cooling coils at 900-s intervals (Timlin et al., 2007) by measuring the mass of water in collecting devices connected to a calibrated pressure transducer.
In the second experiment, plants will be moved to SPAR chambers just before the initial flowering stage. In each SPAR, 12 plants from the same cultivars will be arranged randomized, five SPARs will be used for each hybrid/cultivar, and overall, ten SPARs will be used for the experiment. Five day/night temperature treatments, 21/13, 25/17, 29/21, 33/25, and 37 /29°C, day/night), will be imposed at flowering and continued until maturity. Air temperature in each chamber will be monitored and adjusted every 10 seconds throughout the day and night and maintained within ±0.5°C of the treatment set points measured with aspirated thermocouples. Plants will be irrigated three times a day through an automated and computer-controlled drip system with full-strength Hoagland’s nutrient solution (Hewitt, 1952), which will be delivered at 07:00, 12:00, and 17:00 h, to ensure balanced nutrient and moisture conditions for plant growth. All SPARs will be maintained at 420 or 720 ppm [CO2] until the harvest.
