Paclobutrazol in the in vitro conservation of cassava genotypes

In vitro germplasm conservation allows to extend the interval between subcultures without compromising the viability and genetic integrity of the plant, ensuring a backup of genotypes with high phytosanitary quality. Thus, this study aimed to verify the effect of four concentrations of Paclobutrazol® in inducing minimum growth in five Manihot esculenta accessions from the in vitro Active Germplasm Bank of Embrapa Cassava and Fruits. An experiment was installed using the Murashige and Skoog medium without addition and added with four concentrations of Paclobutrazol® (0.10, 0.20, 0.30, and 0.40 mg L-1), in five in vitro accessions of M. esculenta: BRS Jari (BGM 2041), Cigana (BGM 0264), BRS Poti Branca (BGM 2017), TME 14, and BRS Novo Horizonte. The statistical design was completely randomized in a 5 x 5 factorial scheme, with 15 repetitions. After 120 days of cultivation, the following variables were evaluated: plant height (cm), number of green leaves, number of senescent leaves, number of mini-cuttings, number of shoots, and fresh and dry mass of shoots and roots (mg). Paclobutrazol® caused a reduction in plant height and gain in root mass for all accessions, in addition to preserving the number of green leaves and decreasing leaf senescence for most genotypes. There was a strong dependence of the genotype in relation to the concentration of Paclobutrazol®. The concentration of 0.20 mg L-1 showed potential in the in vitro conservation of M. esculenta genotypes.(AU)

Activated charcoal in the control of oxidation and in vitro growth of Dioscorea spp. nodal segments

In vitrooxidationisaproblem forsome herbaceous and woody species and can causedarkening of tissues and consequently death of explantsand plants Therefore, this study aimed to assess the effect of activated charcoal on in vitro yamcultivation, aiming at reducing or eliminating explant oxidation and optimizing the growth of the genotypes Dioscorea alata var.purpurea(Roxb.) A. Pouchet and Dioscorea rotundataPoir. Nodal segments of approximately 1 cm, extracted from plants previously grown in vitro, were introduced into test tubes containing 10 mL of 2GGC culture medium, plus 30 g L-1sucrose, solidified with 2.2 g L-1Phytagel®and pH adjusted to 5.8 before autoclaving, containing activated charcoal doses of 0, 1, 2, 3 and 4 g L-1. Plants were maintained for 90 days in a growth room, with temperature of 27 ± 1ºC, photon flux density of 30 µmol m-2s-1and photoperiod of 16 hours, after which their development variables were evaluated. Activated charcoal, at the concentration of 4 g L-1considerably promoted the best development of plants, and the species D. alatavar.purpureashowed higher means for all variables studied.(AU)

Abscisic acid and in vitro conservation of Manihot wild species

Abscisic acid (ABA) is associated with bud dormancy, leaf abscission, and germplasm growth inhibition in in vitro conservation. We evaluated the effects of ABA in four wild Manihot accessions and one cassava accession (M. esculenta Crantz) to refine in vitro conservation methods for these species. The experiment was performed at the Laboratory for Tissue Culture from Embrapa, Cruz das Almas, Bahia State, Brazil. The statistical design was completely random in a 5 × 5 factorial scheme [(5 ABA dosages (0, 0.25, 0.50, 0.75, and 1 mg L-1) and 5 Manihot species (M. pseudoglaziovii, M. tristis, M. flabellifolia, M. chlorosticta, and M. esculenta)], with 15 replicates. Mini-cuttings of 1 cm were used, each inoculated in 10 mL of modified Murashige and Skoog medium, solidified with Phytagel® (2.4 g L-1) containing the respective ABA dosages. Tubes containing these mini-cuttings were placed in a germplasm conservation room with an irradiance of 30 µmol m-2 s-1, temperature of 22 ± 1°C, and photoperiod of 12 hours. Plant height (cm), the number of living and senescent leaves, shoots, and mini-cuttings (1 cm), and fresh and dry weights of shoots and roots (mg) were evaluated after 150 days. Growth reduction was prominent in M. pseudoglaziovii, M. tristis, and M. flabellifolia during the in vitro conservation period. In the present study, the addition of ABA did not promote the expected reduction in plant growth.(AU)

Abscisic acid and in vitro conservation of Manihot wild species / Abscisic acid and in vitro conservation of Manihot wild species

Abscisic acid (ABA) is associated with bud dormancy, leaf abscission, and germplasm growth inhibition in in vitro conservation. We evaluated the effects of ABA in four wild Manihot accessions and one cassava accession (M. esculenta Crantz) to refine in vitro conservation methods for these species. The experiment was performed at the Laboratory for Tissue Culture from Embrapa, Cruz das Almas, Bahia State, Brazil. The statistical design was completely random in a 5 × 5 factorial scheme [(5 ABA dosages (0, 0.25, 0.50, 0.75, and 1 mg L-1) and 5 Manihot species (M. pseudoglaziovii, M. tristis, M. flabellifolia, M. chlorosticta, and M. esculenta)], with 15 replicates. Mini-cuttings of 1 cm were used, each inoculated in 10 mL of modified Murashige and Skoog medium, solidified with Phytagel® (2.4 g L-1) containing the respective ABA dosages. Tubes containing these mini-cuttings were placed in a germplasm conservation room with an irradiance of 30 µmol m-2 s-1, temperature of 22 ± 1°C, and photoperiod of 12 hours. Plant height (cm), the number of living and senescent leaves, shoots, and mini-cuttings (1 cm), and fresh and dry weights of shoots and roots (mg) were evaluated after 150 days. Growth reduction was prominent in M. pseudoglaziovii, M. tristis, and M. flabellifolia during the in vitro conservation period. In the present study, the addition of ABA did not promote the expected re

Abscisic acid (ABA) is associated with bud dormancy, leaf abscission, and germplasm growth inhibition in in vitro conservation. We evaluated the effects of ABA in four wild Manihot accessions and one cassava accession (M. esculenta Crantz) to refine in vitro conservation methods for these species. The experiment was performed at the Laboratory for Tissue Culture from Embrapa, Cruz das Almas, Bahia State, Brazil. The statistical design was completely random in a 5 × 5 factorial scheme [(5 ABA dosages (0, 0.25, 0.50, 0.75, and 1 mg L-1) and 5 Manihot species (M. pseudoglaziovii, M. tristis, M. flabellifolia, M. chlorosticta, and M. esculenta)], with 15 replicates. Mini-cuttings of 1 cm were used, each inoculated in 10 mL of modified Murashige and Skoog medium, solidified with Phytagel® (2.4 g L-1) containing the respective ABA dosages. Tubes containing these mini-cuttings were placed in a germplasm conservation room with an irradiance of 30 µmol m-2 s-1, temperature of 22 ± 1°C, and photoperiod of 12 hours. Plant height (cm), the number of living and senescent leaves, shoots, and mini-cuttings (1 cm), and fresh and dry weights of shoots and roots (mg) were evaluated after 150 days. Growth reduction was prominent in M. pseudoglaziovii, M. tristis, and M. flabellifolia during the in vitro conservation period. In the present study, the addition of ABA did not promote the expected re