SCSC 402 salinity stress and Abiotic Stress in Corn and Sorghum

Halophytes

Salt tolerant plants, native to saline soils, can survive brackish water

Glycophytes

Salt sensitive species, most crop species are this, (barley, pearl millet, quinoa), grown in coastal slat marshes.

Effects of sat stress (2)

Osmotic stress & toxic ions

Osmotic stress

Nonspecific stress that can cause water deficits; Na+ and Cl- ions, salinity lowers the soil water potential

Toxic Ions

Accumulation of toxic ions (i.e. Na+) can interfere with nutrient uptake and cause cytotoxicity, resulting in protein denaturation and membrane destabilization

HIgh levels of soluble salts (such as NaCl) can cause

Drought like symptoms in plants due to the osmotic effect

Natural salinity

occurs where there is insufficient rainfall to leach naturally occurring salts from the upper profile

Irrigation-induced salinity

Use of surface or ground water containing dissolved salts for irrigation adds salt

Saline soils have

Excessive levels of soluble salts

Sodic soils have

Excessive levels of sodium adsorbed at the cation exchange sites

Soluble salt concentration: Electrical conductivity (EC)

increases with increasing concentration of electrolytes. The EC is directly related to the ionic strength of the soil solution and the ionic strength depends on the concentration (and charge) of electrolytes

Sodium adsorption ratio (SAR)

assessment of the dispersion of clay aggregates in the soil

Manage saline soils by (2)

Sub-surface drainage, cover crops or planting salt tolerant crops

Salinity management strategies (2)

Establish vegetation to begin to reclaim the soil, electrical conductivity meter

Managing sodic soils (3)

amendments of calcium sulfate (gypsum) and calcium chloride, sodium (Na+) converts into a salt (Na2SO4) and leaches out of the rooting zone, salttolerant crops should be grown to increase soil organic matter and improve soil structure

Salt-tolerant field crops (5)

Barley, cotton, sugarbeet, wheat, sorghum

Salt-tolerant forage crops (4)

Wheat grass, bermuda grass, barley hay, alfalfa

Salt-tolerance mechanisms (5)

Sensing à signaling à ROS, Ca2+, hormones

Na+ exclusion from leaves (HKT1)

Detoxification/extrude Na+ (SOS1)

Compartmentation in the vacuole (NHX)

Osmotic protection system

Mapping QTLs for complex traits (3)

Polygenic, continuous variation, environment interaction

Quantitative trait loci (QTLs)

a region of the genome causing a measurable effect on a trait phenotype

Top crop loss stress in Texas is

Drought

The most sensitive period of development for drought/heat

Flowering

Anthesis-Silk Interval (AIS)

Days between pollen shed and silking