AbstractThis study was undertaken to measure the effect of water stress on yield and yield components in guar(Cyamopsis tetragonoloba[L.] Taub.) grown under water‐stressed and water‐optimal field conditions. Fifteen guar germplasms were grown in irrigated and dryland tests at Lubbock, TX on an Amarillo loam (fine‐loamy, mixed thermic Aridic Paleustoll). Plants in each germplasm were hand harvested at maturity and data recorded for number of racemes/plant, pods/plant, seeds/pod, weight/100 seeds and g/seed/plant. We found differences among germplasms for yield components under both dryland and irrigated conditions. Germ‐plasms responded statistically the same in both moisture levels. Among three pre‐selected cultivars, water use efficiency did not differ statistically. Our analyses indicated that the component of yield most affected by water stress was number of pods/plant. Seed weight, seeds/pod, and racemes/plant each had progressively smaller effects on s