What could cause roots to die from overwatering?

Roots can die from overwatering primarily due to the lack of oxygen. When soil is overly saturated, it fills the air spaces between soil particles with water. This reduction in air spaces limits the availability of oxygen needed for root respiration. Roots require oxygen to perform vital functions, including energy production and nutrient uptake. When they are deprived of oxygen for extended periods, root cells begin to die, leading to poor plant health, stunted growth, and ultimately the death of the plant.

The other options may contribute to plant stress or impact growth in other ways, but they are not the direct cause of root death from overwatering. Excess nutrients can lead to issues like nutrient burn or imbalance rather than directly suffocating roots. High temperatures can affect plant cells and stress overall health, but they do not directly relate to waterlogged soil. Soil salinity affects water availability but typically relates to additional stress due to osmotic pressure, rather than direct oxygen deprivation that results from overwatering.