Straw return significantly enhances wheat yield in higher precipitation environment by promoting larger root diameters, wider xylem channels, and thinner root cortex

Abstract

Background and aims

Straw return is one of the effective methods to enhance soil structure, regulate soil moisture and thus promote root growth and development. However, it remains unclear how returning straw to the field affects wheat grain yield through root morphology and anatomy under different precipitation conditions, especially as research on root anatomy is relatively scarce. This study explored the regulatory mechanisms of straw return on wheat yield by analyzing the morphology, distribution and anatomical structure of wheat roots under different precipitation conditions.

Methods

A field experiment with straw return (S1) and straw removal (S0) was conducted under three precipitation (P) conditions: (1) an increase of 1/3 (P +), (2) normal (P) and (3) a decrease of 1/3 (P-).

Results

The results showed that straw return only under P + and P precipitation conditions reduced the soil bulk density and enhanced the soil moisture. The optimized soil properties of the straw treatment promoted deep root growth and root anatomical structure, leading to significant increases in root biomass, root surface area, root length density, root volume, root diameter and root cortex thickness under both P + and P conditions. Grain yield and aboveground biomass of the straw return treatment increased by 7.8% and 15.1% under P + conditions, and by 7.3% and 13.5% under P conditions, respectively throughout the two growing seasons.

These results are attributed to the progress of root system and root anatomical structure in the lower soil, which absorbs and transports more soil water.

Conclusions

Our findings demonstrated that increased precipitation ensured grain and biomass production, while also enhancing the benefits of incorporating straw into the fields.