Tomato greenhouses in the Canary Islands, Spain, were surveyed to estimate frequencies of resistance to benzimidazoles, dicarboximides, anilinopyrimidines and N-phenylcarbamates in Botrytis cinerea. Resistance to carbendazim, iprodione, pyrimethanil and diethofencarb was found in 74.2, 86.4, 28.8 and 31.8% of isolates, respectively. Benzimidazole- and anilinopyrimide-resistant isolates were highly resistant, showing EC50 values above 500 µg/ml carbendazim and a mean EC50 value of 28.42 µg/ml pyrimethanil, respectively. By contrast, a low level of resistance was observed among dicarboximide-resistant isolates (mean EC50 value of 1.81 µg/ml iprodione). Phenotypes with double resistance to carbendazim and iprodione, and triple resistance to carbendazim, iprodione and pyrimethanil were the most common, occurring in 36.4 and 28.8% of isolates. The surveyed greenhouses had never been treated with fenhexamid and Signum™ (pre-packed mixture of boscalid and pyraclostrobin), and baseline sensitivities of B. cinerea isolates to these fungicides were determined. The EC50 values were within the range of 0.009-0.795 µg/ml fenhexamid and of 0.014-0.48 µg/ml Signum. In addition, available formulations based on elicitors of plant defense response and biocontrol agents were evaluated against B. cinerea in tomato plants under semi-controlled greenhouse conditions, the yeast Candida sake CPA-1 being able to reduce gray mold significantly when it was applied on petiole wounds and the plants were inoculated 24 h later. Likewise, C. sake was effective against B. cinerea in harvested tomato fruits, yeast-treated tomatoes showed a 70.66 and 30.31% reduction in the diameters of decay lesions compared with controls after 10 days of storage at 20 and 9 °C, respectively.
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.
Com o objetivo de determinar: . Curva de crescimento da planta; . Concentração e acumulação de nutrientes pela cultura em função de idade; . Exportação de nutrientes através das folhas. Foi instalado um experimento de campo na Estação Experimental de Tietê, localizado em um solo Podzólico Vermelho Amarelo var. Lara sem o emprego de fertilizantes. O delineamento experimental foi o inteiramente casualizado com 4 repetições. Amostragem de plantas foram efetuadas 12, 24, 48, 60 e 72 dias após o transplante. Os autores observa ram que a maior velocidade de acúmulo de matéria seca ocorreu próximo aos 48 dias após o transplante. As concentrações mínimas dos nutrientes ocorreram próximo ao período de máximo acúmulo de matéria seca. O acúmulo máximo de matéria seca e de nutrientes ocorreu aos 72 dias após o transplante. As quantidades totais de nutrientes absorvidos pela cultura obedeceram a seguinte ordem: K N >Ca> Mg> P S Fe Mn B Zn Cu. A exportação de nutrientes pelas folhas obedeceram a seguinte ordem: K N Ca Mg > P S Fe> Mn > Zn B Cu.
Seven cultivars of pepper (Capsicum annuum L.), representing both frying and bell types, and open-poflinated and hybrid varieties, were planted at population levels of 35,878, 53,818, and 71,757 plants/ha. The lowest density is the conventional rate in Puerto Rico. They were planted af the Fortuna Substation, Juana Díaz, Puerto Rico. Irrigation was supplied throughout the dry season. After the fourth harvest, two replicates were pruned to 12 cm for a second crop. Planting density affected yield but not fruit size. There was a density x cultivar interaction at P = 0.09 for yield. Doubling the population increased yield 12 to 40%. Response to pruning was cultivar-specific. Total yield was 25 to 100% greater than yield before pruning. Both practices could serve as low capital innovations for the tropics.
DRY WEIGHT ACCUMULATION IN ARRACACHA PLANT PARTS
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