قارن الطرق

	مؤشر مساحة الورقة	معادلة بنمان-مونتيث
المجال	علم المحاصيل	علم المحاصيل
العائلة	Process / pipeline	Process / pipeline
سنة النشأة	1947	1948-1965
صاحب الطريقة	Donald J. Watson	Howard Latimer Penman, John Monteith
النوع	Plant morphometric measurement	Mechanistic evapotranspiration model
المصدر التأسيسي	Watson, D. J. (1947). Comparative physiological studies on the growth of field crops: I. Variation in net assimilation rate and leaf area between species and varieties, and within and between years. Annals of Botany, 11(43), 375-407.	Penman, H. L. (1948). Natural evaporation from open water, bare soil and grass. Proceedings of the Royal Society A, 193(1032), 120-145.
الأسماء البديلة	LAI, Leaf area, Canopy structure	PM Equation, FAO-56 PM, Evapotranspiration Model
ذات صلة	3	3
الملخص	Leaf Area Index (LAI) is a dimensionless quantity that measures the total one-sided area of leaves per unit ground area covered by a canopy. It quantifies canopy density and structure: LAI = 0 for bare soil, LAI = 1 for a thin crop, LAI = 3-6 for dense cereal or grass canopies, and LAI > 8 for dense forest. LAI is a key variable in crop growth models, evapotranspiration estimation, and remote sensing because it directly controls light interception, photosynthesis, and water loss from vegetation.	The Penman-Monteith equation is a mechanistic model for estimating evapotranspiration (ET), the combined loss of water from soil and plant canopies to the atmosphere. First proposed by Penman (1948) for bare soil and water surfaces, then extended by Monteith (1965) to incorporate plant resistance to water vapor diffusion, it has become the international standard for water balance studies, crop water requirement calculation, and hydrological modeling.