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Studies were conducted at the Fortuna Substation for 10 years to determine the effect of 5 interstems on growth and yield components of 2 commercial mango varieties. The interstems did not significantly affect the rootstock diameter when Edward variety was the scion; however, they did with Palmer variety as scion at the 3- and 6-year stages only, Irwin interstem diameter at the 3-year stage for Edward and Palmer, and at the 6- and 9-year stages for Edward, was significantly thicker than that of the other interstems. Edward on Manzano Tetenené had the thinnest interstems. In the two varieties studied, the scion diameter was scarcely affected by the interstems at 3, 6 and 9 years after transplanting. Edward and Palmer grafted on Irwin as interstems had significantly lower scion/interstem ratios. The opposite was true when these varieties were grafted on Julie. Three years after planting, the smallest trees were those of Edward and Palmer grafted on Malda; 6 and 9 years after planting, those of Edward grafted on Malda and Manzano Tetenené. Yield efficiency decreased significantly with tree age and size. Thus, there was a negative correlation between these parameters. Edward produced significantly more fruits than Palmer at the 3-year-old stage. Edward as interstem grafted on Eldon produced significantly more fruits at the 3-, 6- and 9-year stages than when grafted on the other interstems. Palmer grafted on Eldon was significantly more precocious than when grafted on the other interstems. Malda and Manzano Tetenené as interstems significantly reduced tree size of Edward; Julie as interstem reduced the size of Palmer.

En el Centro de lnvestigación y Desarrollo de Fortuna, en la costa semiárida del sur, se estudió el crecimiento y el rendimiento de mangoteros en tres edades usando diferentes combinaciones de patrones e injertos. Se encontró que el diámetro de los árboles injertados varió según su edad, pero que después de 6 años la variedad Palmer tenía el tronco más grueso. Le seguieron las variedades Edward e Irwin. Eldon fue el patrón más eficaz en reducir el diámetro del injerto durante los primeros 6 años de crecimiento, pero su efecto desapareció después de 9 años. La razón injerto/patrón varió con la edad, pero después de 9 años era menor en la Edward injertada sobre Tetenene. A los 6 años de crecimiento, la variedad Palmer tenía la copa más ancha; le siguieron las variedades Edward e Irwin. Eldon, como patrón para las variedades Palmer e Irwin, causó la formación del diámetro y el volumen de copa más pequeños independientemente de la edad de los árboles. Asimismo, los árboles de la variedad Palmer fueron más altos que los Edward e Irwin sin importar la edad de los árboles. Con Eldon como patrón los árboles de las variedades Irwin y Palmer fueron significativamente más pequeños, aunque después de 9 años el efecto del patrón sobre la altura no fue significativo. La eficiencia de rendimiento no se afectó significativamente por el patrón en las variedades Edward y Palmer, pero se afectó significativamente cuando la variedad Julie se injertó sobre Julie. La producción y el peso de las frutas por árbol estuvieron relacionados con el tamaño de los árboles, encontrándose que una reducción en tamaño reducía significativamente el número total y el peso de las frutas.

Two identical experiments were conducted to study the effect of direct seeding and transplanting on the yield, quality, and general performance of head cabbage at Fortuna and Isabela, Puerto Rico. In these experiments the hybrid varieties Market Prize, Market Topper, King Cole, and Head Start were tested under direct seeding and transplanting bare-rooted and banded seedlings. The results indicated that the effect of planting methods on variety performance was largely influenced by soil conditions. At Fortuna, where the soil could be tilled to provide a good seedbed, the mean marketable yields of all hybrids was higher from direct seeding than from transplants. Also, the hybrids matured earlier and their maturity was more uniform when direct seeded. However, at Isabela, where the soil was not appropriate to obtain a good tilth, the transplanting methods significantly outyielded direct seeding. The highest yields of marketable cabbage, both from direct seeding and transplanting methods, were obtained from the hybrid Head Start. Good yields of excellent quality were obtained, however, regardless of variety, planting method, and location.