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ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Water Management and Systems Research » Research » Publications at this Location » Publication #312498
Title: Root growth dynamics linked to aboveground growth in walnuts (Juglans regia L.)

Author
item CONTADOR, MARIA LORETO - University Of California
item Comas, Louise
item METCALF, SAMUEL - University Of California
item STEWART, WILLIAM - University Of California
item GOMEZ, IGNACIO PORRIS - University Of California
item NEGRON, CLAUDIA - University Of California

Submitted to: AoB Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/30/2015
Publication Date: 5/22/2015
Citation: Contador, M., Comas, L.H., Metcalf, S.G., Stewart, W.L., Gomez, I., Negron, C. 2015. Root growth dynamics linked to aboveground growth in walnuts (Juglans regia L.). AoB Plants. doi: 10.1093/aob/mcv064.

Interpretive Summary: Examination of plant growth belowground is scant compared to that aboveground but needed to understand whole plant responses to environmental factors. Effects of canopy and soil water manipulation on the seasonal timing and vertical distribution of root growth was analysed in walnut. Root growth in walnuts followed a unimodal curve with one marked flush of root growth starting mid-May and peaking mid-June. Root growth declined later in the season, corresponding to increased soil temperature, as well as to the period of major carbohydrate allocation to reproduction. Canopy and soil moisture manipulation did not further affect the timing of root production but did influence the vertical distribution of roots through the soil profile. Water deficit appeared to promote root growth in deeper soil layers for mining soil water. Canopy removal appeared to promote shallow root growth, which could have negative effects under last season water shortfalls or positive effects in years with wet springs. Further studies on root growth responses and their regulation in more locations are required to more fully understand the potential effects of a shifting climate on cropping and wild ecosystems.

Technical Abstract: Background and Aims: Examination of belowground plant responses to canopy and soil moisture manipulation is scant compared to that aboveground but needed to understand whole plant responses to environmental factors. Plasticity in the seasonal timing and vertical distribution of root growth in response to canopy and soil water manipulation was analysed in walnut (Juglans regia L. variety ‘Chandler’). Methods: We studied root growth patterns within the soil profile using minirhizotron techniques. Key Results: Root growth in walnuts followed a unimodal curve with one marked flush of root growth starting in mid-May, with a peak in mid-June. Root growth declined later in the season, corresponding to increased soil temperature, as well as to the period of major carbohydrate allocation to reproduction. Canopy and soil moisture manipulation did not influence the timing of root production but did influence the vertical distribution of roots through the soil profile. Water deficit appeared to promote root growth in deeper soil layers for mining soil water. Canopy removal appeared to promote shallow root growth, which could have negative effects under last season water shortfalls or positive effects in years with wet springs. Conclusions: Root vertical distribution appeared to have greater plasticity than timing of root growth in this system. Further experiments controlling soil temperature and reproductive growth will be needed to separate these effects on root growth. More studies on root growth responses and regulation of these responses in more locations are required to understand the potential effects of a shifting climate on cropping and wild ecosystems.