Establishment of rhizoma perennial peanut (Arachis glabrata) under irrigation at two semiarid sites in the Caribbean.

Two experiments were conducted to determine time for full establishment of rhizoma perennial peanut (RPP) under irrigation. Experiment one (E1) and experiment two (E2) were conducted, respectively, at the Lajas and Fortuna Substations of the Agricultural Experiment Station of the University of Puerto Rico. At Lajas, rhizomes of accessions USDA-ARS no. 17033, 17050, 17052, 17097 (PI no. 276233, 262826, 262833, 262839, respectively) and cultivars Florigraze and Arbrook, planted at 0.76 and 1.5 m apart in rows, were compared for rate of establishment at 60,120, 180 and 240 days postplanting. At Fortuna, rhizomes of accessions 17033 and 17097, and cv. Florigraze were compared at 80,160, and 240 days postplanting. In E2, plots were subjected to the following weed control methods: (1) manual, (2) mowing, and (3) chemical. Time to full establishment in E1 increased from about six months to eight with an increase in planting distance from 0.76 to 1.5 m. Accessions 17033 and 17097 and cv. Florigraze showed a tendency for faster lateral spread prior to 120 days postplanting than the other RPPs. However, peanut genotypes achieved fufl cover at about the same time. The use of herbicide in E2 was the most effective method for promoting faster cover of RPP plants. Establishment of the stand was achieved prior to 240 days in plots receiving weed control treatments 1 and 3, whereas those receiving treatment 2 achieved only 62.5% cover. Compared to a tropical grass, RPP exhibits a slower pattern of lateral spread and requires a longer time for full establishment when planted under similar conditions. However, reducing planting distance and using herbicides to control weeds are management strategies that can reduce time for full establishment of the RPP stand.