Most literature reviews focus on a specific topic. The purpose of this paper, however, is to review the contributions made by a multidisciplinary team of researchers at a specific location (Puerto Rico) over a period of several decades. This paper documents bean research of the University of Puerto Rico and the USDA-ARS Tropical Agriculture Research Station during the past century. The following illustrates the merits of continuity of effort in research and shows that research often follows a logical sequence of actions to solve problems related to genetic improvement as well as to study biotic and abiotic factors that affect common bean production in Central America and the Caribbean. Finally, this narrative demonstrates that the ongoing development of improved bean germplasm lines and cultivars is cyclical and builds upon previous research achievements. IntRodUctIon The common bean (Phaseolus vulgaris L.) is an important component of the traditional diet in Puerto Rico. The 1900 report of the USDA Puerto Rico Agricultural Experiment Station (USDA-PRAES) noted that rice and beans were staple crops in Puerto Rico and found on the tables of both the rich and poor. Smit et al. (2007) noted that annual per capita consumption of grain legumes, mostly dry beans, in

En la costa suroeste semiárida de Puerto Rico se probaron 40 genotipos de habichuela seca para determinar en parcelas experimentales el efecto de la inoculación con los residuos de cosecha de habichuela que estuvieron altamente infectados con Macrophomina phaseolina. Los análisis de varianza indicaron que hubo diferencias significativas entre los índices de severidad en los genotipos probados. La pudrición gris del tallo aumentó aproximadamente 40% entre las fases de la formación de la vaina y la madurez fisiológica. Hubo una relación altamente significativa (r=0.66**) en la severidad de la enfermedad cuando se midió a los 70 y 90 días después de sembrar. Entre los 40 genotipos de habichuela evaluados, Cuarentena y RIZ 44 mostraron altos grados de susceptibilidad; 8437-22 fue el genotipo más resistente a M. phaseolina.

RESISTANCE AND SUSCEPTIBILITY OF BEANS, PHASEOLUS VULGARIS L., TO ASHY STEM BLIGHT, MACROPHOMINA PHASEOLINA (TASSI) GOID

Forage sorghum [Sorghum bicolor L. Moench 'Brown midrib' (BMR)] and annual legumes lablab [Lablab purpureus L. 'Rongai' (L)] and mucuna [Mucuna pruriens L. 'Vine 90 d' (M)] are suitable fodder for the dairy industry in Puerto Rico, but BMR harvested at 90 days, usually has low crude protein (CP, 6%) content, which limits its usefulness. There is the possibility of increasing the CP by intercropping legumes with BMR, but this option has been only slightly investigated. This study proposes to compare BMR in monoculture and in intercropping with 'Rongai' (SL) and 'Vine 90 d' (SM), in addition to L and M in monoculture, in terms of total leaf mass (FM) and botanical components (sorghum, legumes and weeds) and chemical (CP and fiber fractions) at two harvest times. The experimental plots (25 m2) were sown in February and August 2008 in a randomized complete block design with five replications. At each harvest time, 2 m2 MF area was sampled 90 days after sowing. Data were analyzed by using the MIXED procedure of SAS and mean separation tests were performed by using F-protected LSD at 95% level of confidence. No significant differences (combining fodder botanical component and weeds) were detected for the total MF between BMR and BMR associated with legumes in monoculture, with mean values of 8.94, 8.81, and 8.42 Mg/ha for BMR-'Rongai', BMR-'Vine 90 d', and BMR, respectively. Overall, there was no significant difference in MF between May and August (8.1 vs. 7.5 Mg/ha). 'Rongai' yield (Mg/ha) did not change between May and August (3.6 vs. 3.0) but was lower in the intercrop (2.74) than in monoculture (3.94). 'Vine 90 d' had the lowest yield of 2.8 and 1.3 Mg/ ha in May and August, respectively. No differences (P > 0.05) in NDF and ADF content between BMR and BMR-'Rongai'-'Vine 90 d', whose values were 60.1 and 63.9% and 40.1 and 46.5%, respectively. However, differences (P < 0.05) were found in CP content between monoculture and intercropping, with values of 14.1, 11.1, and 6.0% for 'Rongai', 'Vine 90 d', and sole BMR, respectively, whereas the BMR-'Rongai' and BMR- 'Vine 90 d' CP were 9.8 and 9.1%, but these last values exceed by three units the percentage in BMR. In conclusion, BMR intercropped with 'Rongai' and 'Vine 90 d' improved the forage chemistry and helps to control weeds while favoring the performance of desirable botanical components.