Table 7.

Studies that report effects of P deficiency on the root-to-shoot ratio (R_S), root length per shoot biomass (LEGN_SHOOT), root diameter (DIA) and specific root length (SRL) at the field scale.

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

DECREASE (in red): diminished effect, VARIABLE (in yellow): diverse, inconclusive or no effects, and INCREASE (in green): higher effect 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 .