Table 6.

Studies that report effects of P deficiency on total root length and/or root length density (TRL-RLD) and root biomass (RBIO) at field scale.

Reference	Crop	Soil	Factors	TRL-RLD	RBIO
(Ho et al., 2005)	common beans		GEN IRR	DECREASE
(Miguel et al., 2015)	common beans	loamy	GEN	DECREASE
(Ochoa et al., 2006)	common beans		GEN	DECREASE	DECREASE
(Deng et al., 2014)	maize	silty loam	LEV	DECREASE	DECREASE
(Sheng et al., 2012)	maize	clay loamy	LEV	DECREASE	DECREASE
(Zhang et al., 2012)	maize	loamy and silt	DEV	DECREASE	DECREASE
(Duan et al., 2020)	oilseed rape	Alfisol	DEV GEN	DECREASE	DECREASE
(Ao et al., 2010)	soybean	Acidic red soil	GEN	DECREASE
(Hadir et al., 2021)	sugar beet	silty loam	DEV	DECREASE	DECREASE
(Teng et al., 2013)	wheat	silty	LEV YEAR	DECREASE	DECREASE
(Henry et al., 2010b)	common beans		GEN IRR	VARIABLE
(Henry et al., 2010a)	common beans		GEN	VARIABLE
(Miguel et al., 2013)	common beans	loamy	GEN	VARIABLE
(Strock et al., 2018)	common beans	silty loam	GEN	VARIABLE
(Li et al., 2017)	maize	clay loamy	LEV	VARIABLE	DECREASE
(Otani and Ae, 1996)	others		CROP	VARIABLE
(Jing et al., 2004)	soybean	Acidic red soil	GEN	VARIABLE
(Steingrobe et al., 2001)	winter barley	loamy	DEV	VARIABLE
(Gutierrez-Boem and Thomas, 1998)	soybean	silty	IRR LEV	INCREASE

DECREASE (in red): diminished TRL-RLD/RBIO, VARIABLE (in yellow): diverse, inconclusive or no effects on TRL-RLD/RBIO, and INCREASE (in green):a large TRL-RLD/RBIO in case of deficient as compared to non-deficient conditions. Factors refer to the variables studied in each manuscript. LEV: several levels of N applied, DEV: several development stages investigated, YEAR: several years investigated, IRR: water treatments applied (such as irrigation and drought), PLAN: several planting methods tested, SOIL: several soil types tested, GEN: diverse genotype tested, SITE: different sites tested, TILL: several tillage practices tested, CROP: several crops tested. For more details refer to SI Table 2 .