Two field experiments, both with Cubanelle and Yollow Wonder peppers (Capsicum annuum L.), were conducted at the Juana Díaz Research and Development Center in 1981-82. Weeds were induced to grow through periodic irrigations for 16 days before peppers were transplanted. Either glyphosate or paraquat at 1.12 kg ai/ha were then applied to control emerging weeds in two separate experimental areas 5 days before setting out transplants. Oxyfluorfen at 1.12 kg ai/ha applied 2 days before transplanting peppers caused the highest phytotoxicity (significant at P=0.05) as recorded during 14, 28 and 42 days after treatment in both experiments. Neither alachlor (1.68 kg ai/ha), oxadiazon, trifluralin nor pendimethalin applied 2 days before transplanting at 1.12 kg ai/ha was phytotoxic to peppers. There were no significant differences in Cubanelle or Yollow Wonder pepper yields among herbicide treatments and handweeded check. The highest pepper yields (47,771 and 44,964 kg/ha) were obtained in plots treated initially with glyphosate and later by either paraquat directed postemergence spray or oxadiazon pre-transplant at 1.12 kg ai/ha each, respectively. In the other experiment, hand-weeded check and preplant application of paraquat at 1.12 followed by oxyfluorfen at 1.12 kg ai/ha were the highest yielders with 47,771 and 44, 964 kg/ha, respectively.

An experiment was conducted on a San Anton (Cumulic Hasplustolls) fine loamy mixed isohyperthermic in the southern irrigated coastal plain of Puerto Rico, to evaluate the influence of various N-P-K levels on yield and quality of onion (cultivar Texas Grano 502). All P and K fertilizer were broadcast and mixed with the soil at planting. Half of the N fertilizer was broadcast at planting and half was banded 6 weeks later between rows and left uncovered. Mean yield differences attributable to fertilizer levels were not significant. The soil seems to have sufficient available native N to meet this crop's needs. This may be in part attributable to continuous fertilizer applications over the years for sugarcane production in this soil. An average onion production of 22 metric tons/ha was obtained. The world average production is 11 metric tons/ha. Based on the results obtained, the production of onions in th is soil is recommended for two reasons: 1) The high tonnage that can be obtained, and 2) the low investment on fertilizers if planted on soils of high fertility, especially if previously used for sugarcane and fertilized over a long period.

Quantitative information on the performance of arracacha is limited as to the influence of sett size and depth. Setts for propagation of this crop vary in size and fresh weight. Depth of planting appears to influence yield. The objectives of this study were to evaluate the influence of combinations of sett fresh weight and depth of planting on arracacha's emergence, stand, and dry matter and corm fresh weight at harvest, and to assess the quantity and fresh weight of setts produced by a plant after completing the growing cycle. Plants grown from setts weighing 36 g and 60 g did not differ in dry weight, leaf area, fresh weight of the corm at harvest nor in percentages of emergence and stand. Plants from the setts weighing 16 g had less leaf area, less corm dry weight and fewer percentages of emergence and stand than plants from the setts of 60 g. Planting deeper significantly increased corm fresh and dry weights, but decreased the percentages of emergence and stand. Differences in the size of the setts produced by the plant are in part a consequence of the sequential development of the buds within the corm. In plants sampled at 228 and 256 days after planting the number of setts ranged from 10 to 23, averaging 16 ± 4 SD per plant. At harvest, the fresh weight of individual setts ranged from 9 to 73 g, averaging 38 g ± 20 SD. Avoiding the use of small setts may improve chances for better stand and productivity.

Two forage sorghum hybrids ( ATx 623 X GL and FS25A) were grown from April 1985 to February 1987 at the Agricultural Experiment Station of the University of Puerto Rico at Lajas, Puerto Rico to determine the influence of maturity stage increases of 10 days (from the 45th to the 85th day) and how the presence and severity of foliar diseases affect the dry forage and crude protein yields. Dry matter content was higher for FS25A (16.1%) than for ATx 623 X GL (14.9%) whereas total yield for dry matter (DMY) was higher for ATx 623 X GL (3.84 t/ha) than for FS25A (3.51 t/ha). Both content and yield of dry matter increased with maturity stage in both genotypes. The sorghum hybrids did not differ significantly in crude protein content (CPC), but crude protein yield (CPY) was higher for ATx 623 X GL (421.6 kg/ha) than for FS25A (358.9 kg/ha). CPC declined with increased plant maturity. Foliar diseases appeared to limit DFY and CPY in both sorghum hybrids. Downy mildew, leaf blight, rust, grey leafspot, and zonate leafspot appeared seasonally. Leaf blight and downy mildew were the most prevalent from January to May, grey leafspot from May to September, and zonate leafspot from September to November. Rust was severe during all seasons.

LACK OF RESPONSE OF SWEET PEPPERS TOP LEVELS, P PLACEMENT, AND TIMING OF N APPLICATION IN SOUTHERN PUERTO RICO