Examinando por Autor "Salas, Eduardo"

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Biomass dynamics of Erythrina lanceolata as influenced by shoot-pruning intensity in Costa Rica
(Springer, 2003) Berninger, Frank; Salas, Eduardo
Pruning of agroforestry trees, while reducing shade of the crops, usually reduces both biomass production and nitrogen fixation. Short pruning cycles are often not sustainable on the long run, because tree production declines over subsequent pruning cycles. We compared biomass and labile carbohydrate dynamics of Erythrina lanceolata Standley (Papilionaceae) shade trees under total and partial pruning regimes in a vanilla (Vanilla planifolia L.) plantation in South-western Costa Rica. The highest biomass production was measured in the unpruned control, followed by trees with 50% of the leaf pruned every three months, while total pruning every six months resulted in the lowest biomass pruduction. In the more productive treatments, a higher proportion of the production was in branches. Because, the N content of woody branches was high, they were important for nitrogen cycling. In the partial pruning treatment more nitrogen was returned to the soil from litter and woody branches than from pruned leaf. Sugar concentrations were not different between treatments and the dynamics of non-structural carbohydrates (sugar and starch) seems to depend more on plant phenology than pruning treatment. However, the starch concentrations in the total pruning were lower than in the other treatments.
Effect of nematicide rotation on banana (Musa AAA cv. Williams) root nematode control and crop yield
(Universidad Nacional de Colombia, 2019) Jaramillo, Julio; Vintimilla, Marlon; Rubio, David; Soto, Gonzalo; Tobar, Mauricio; Salas, Eduardo; Araya, Mario
The effects of nematicide rotation on banana (Musa AAA cv. Williams) root weight, root nematode control, and crop yield were compared in a commercial banana plantation in Ecuador, testing six treatments in a randomized complete block design with six replicates. Treatments consisted of two, three and four different nematicide cycles per year plus the untreated control. Regarding the untreated plants and averaging the 24 root nematode samplings after treatment application, the nematicide applications reduced significantly R. similis (P<0.0001) between 20 and 49%, Helicotylenchus spp. (P<0.0001) between 31 and 51%, and total nematode populations (P<0.0001) between 29 and 49%. Accordingly, in the treated plants, there was an increase between 16 and 21% in living root weight (P=0.0003), and its percentage (P<0.0001) reached between 74.5 and 81.7% in the follower suckers. In addition, the death of roots by nematodes decreased (P=0.0009) between 20 and 46%. At harvest, nematicide applications increased bunch weight (P=0.0002; P=0.0467), ratio (P=0.0003 at 12 months), ratooning (P<0.0001; P<0.0001) and the number of boxes of 18.14 kg (P<0.0001; P=0.0005) per hectare per year at 12 and 24 months after treatment application, respectively. Plants treated with nematicides increased yield between 671 and 1,158 (12.2 - 21 t) and the number of boxes of 18.14 kg per hectare per year also increased between 545 and 1,046 (9.9 - 19.0 t), which resulted in a net profit between US $3,266 - $5,750 and between US $2,587 and $5,144 per hectare per year at 12 and 24 months after treatment application, respectively.