1. Results showed in Figure 1 indicated that WE mean for grain pearl millet was higher 84% than corn and 22% than sorghum for the highland location. WE mean for pear millet was higher in 61% than corn, and 45% than sorghum for the lowland location. Similarly, Figure 2 show that WE mean for dry forage pearl millet was higher 173% than corn and 17% than sorghum for the highland location, whereas WE for pearl millet was higher in 41% than corn, but lower 4% than sorghum for the lowland location.CONCLUSION Our data suggest that under the rainfall conditions of the season, pearl millet crop is an excellent alternative for grain and forage production in the high and lowland locations of the study area, compared to sorghum and corn.REFERENCES Blum, A. 1988. Productivity and drought resistance of genetically improved cultivars as compared with native landraces of sorghum. Sorghum Newsletter 31: 41. (Abstract- SMIC-ICRISAT). Fisher, K. S. and A. F. E. Palmer. 1980. Yield efficiency in tropical maize. Symposium on “Potential productivity of field crops under different environments” IRRI, Philippines. Maiti, R. K. and G. S. Gomez. 1990. Effect of four sowing date environments on growth, development and yield potential of 15 pearl millet cultivars (Pennisetum americanum L. Leeke) during Autumn-Winter season in Marin, N.L., México. Muchow, R.C. 1989. Comparative productivity of maize, sorghum and pearl millet in a semi-arid tropical environment II. Effect of water deficits. Field Crops Research, 20:207- 219. ABSTRACT Drought is the main limitation for an adequate agricultural activity in the State of San Luis Potosi, Mexico. One out of three planted corn or sorghum hectare is lost, approximately 120,000 hectares per year, due to drought. Three forage and three grain pearl millet, sorghum, and corn genotypes were evaluated in three different climatic locations (high, middle, and lowlands, located at 1520, 1100, and 47 m above sea level) in San Luis Potosi State, Mexico. Water efficiency (WE) was estimated dividing grain and forage yield by seasonal rainfall in each location. Results showed that under the rainfall conditions of the season, pearl millet crop was an excellent alternative for grain and forage production in the high and lowland locations of the study area, compared to sorghum and corn.INTRODUCTION In San Luís Potosí, Mexico, the most important crops, from a social and acreage scope, are corn (Zea mays) and sorghum (Sorghum bicolor) with annual average planted area, from 1998 to 2002, under dryland conditions of 209,000 and 27,000 hectares, and a mean yield of 0.638 and 1.992 ton ha -1, respectively. These productions are considered very low, becasue they are below the national mean, which are 2.006 and 2.655 ton ha -1 for corn and sorghum. Corn and sorghum yields are low due to drought, pests, and diseases damages during crop season, which caused one out of three planted hectares is lost. Researches are looking for short season, drought tolerant, grain or forage crops, with a better adjustment than corn and sorghum to season rainfall of the study area. Pearl millet (Pennisetum americanum) has been tested in the last three seasons as an alternative crop. The objective of this study was to estimate the pearl millet forage and grain water efficiency, compared to these of corn and sorghum. MATERIALS AND METHODS This study was carried out in San Luis Potosi, Mexico, with geographical coordinates of 21º 09´ 35´´ and 24º 33´ 25´´ N, latitude and between 98º 19´40´´ and 102º 17´ 30´´ W, longitude. Three grain (G) and three forage (F) pearl millet (ICMV-88903,G, ICTP-8203,G, 57135Ax5800IR,G, 59043Mx68A4R4w,F,378-2MxFS#1,F, and 413/59052Bx70-2100,F); sorghum (RB-300,G, esmeralda, G, fortuna, G, super sweet II, F, silo miel, F, and great plus, F); and corn (H-220, G, VS-101, G, H-435, G, H-437, F, V- 454, F, and a maize land variety, F) genotypes were evaluated in three different climatic locations (high, middle, and lowlands, located at 1520, 1100, and 47 m above sea level) in San Luis Potosi State. WATER USE EFFICIENCY OF PEARL MILLET, SORGHUM AND CORN UNDER DRYLAND CONDITIONS José A. Hernández-Alatorre 1, Francisco Zavala-García 2, Miguel A. Martinez-Gamiño 1, Cesario Jasso-Chaverria 1 and Eusebio-Jr. Ventura-Ramos 3 1 INIFAP-Mexico, 2 Universidad Autonoma de Nuevo Leon, 3 Universidad Autonoma de Queretaro The experiments were sown on clay loam, clear to black soils. Trials were conducted during the Spring-Summer season of 2004, and rainfall during the development of the crops was 392, 446, and 417 mm in the high, middle and lowland location, respectively. A split plot design was used, using species as main plot and varieties as subplot, with four replications for forage and four replications for grain. Main-plot size was 19.2 m x 5.0 m and sub-plots measured 6.4 m x 5.0 m. Each sup-plot consisted of 8 rows spaced 0.80 m apart. The cultural details and measurements are given in brief: the plant population densities of corn and sorghum were 5 and 18 plants m- 2, for each location; for pearl millet was 25 plants m- 2. All crops were grown under medium to high natural fertility, and pests and diseases were controlled. Data recorder were anthesis, maturity, forage and grain-yield, seed size and seed number. Water efficiency (WE) was estimated dividing grain and forage yield by seasonal rainfall, registered since planted day to physiological maturity of each crop, in each location. RESULTS Significant differences among species were found in grain-yield and dry forage-yield (Table 1 and 2) in most locations. Pearl millet genotypes outyielded or were significantly similar to sorghum or corn genotypes. Table 1. Grain-yield (ton ha -1 ) of pearl millet, sorghum and corn under dryland conditions. San Luis Potosi, Mexico. 2004. Table 2. Dry forage-yield (ton ha -1 ) of pearl millet, sorghum and corn under dryland conditions. San Luis Potosi, Mexico. 2004. Figure 1. Water efficieny mean (kg ha -1 m -3 ) for grain pearl millet sorghum, and corn under dryland conditions. San Luis Potosi, Mexico. 2004. Figure 2. Water efficieny mean for dry forage (kg ha -1 m 3 ) for pearl millet, sorghum and corn under dryland conditions. San Luis Potosi, Mexico. 2004. Crop Location HighlandMidlandLowland Pearl millet4270 a1660 a3850 a Sorghum2400 b2770 a3675 a Corn2170 b2890 a3310 a DMSα 0.05111619961062 Crop Location HighlandMidlandLowland Pearl millet22.3 a5.4 b16.9 b Sorghum19.9 a9.9 a28.5 a Corn8.5 b4.0 b12.1 c DMSα 0.057.33.84.6 Means with the same letter are not significantly different at P ≤ 0.05