Aims: This study was conducted with a view to validate and compare flowering models (indices) containing temperature, heat units, photoperiod and their combinations developed to predict the number of days to flowering in maize in different agro-ecological zones of West and Central Africa.
Study Design: Simple and multiple linear regression models developed on 100 maize varieties as the inverse of the number of days from planting to flowering (1/f) on values of temperature, heat units and photoperiod were validated.
Place and Duration of Study: One hundred maize varieties of different maturity groups were evaluated for days to tasseling, anthesis and silking at the Teaching and Research Farm (TRF) of Obafemi Awolowo University Ile-Ife, Nigeria during late and early cropping seasons of 2007/2008 and 2008/2009 respectively. The 2007 developed models were validated with 2008 early, 2008 late, 2009 early, 2012 late, 2013 early seasons and flowering data of the other agro-ecologies.
Methodology: The developed flowering models were validated with the flowering data of the 100 varieties obtained during the 2008 early, 2008 late, 2009 early, 2012 late and 2013 early seasons. Furthermore, flowering dates and the weather data from research stations in the Forest, Guinea savanna and Sudan savannah agro-ecologies were used to validate the flowering models.
Results: The thermal model best predicted the time from planting to the expression of anthesis. The thermal model accurately predicted the anthesis of about 30-40% of the varieties in the 2008 early and late seasons, trial in environment different from the one in which it was developed in the rainforest agro-ecology. Heat units models closely predicted 10 varieties from the hundred varieties evaluated in this study in 2012 late and 2013 early cropping seasons. In the Southern Guinea savannah and Sudan savannah, none of the models predicted the number of days to the flowering traits of some of the 100 varieties correctly.
Conclusion: Predicted days to anthesis due to thermal and heat units models are the best models to classify maize varieties into maturity groups in the rainforest agro-ecology The thermal model correctly classified over 40% of the 100 maize varieties into maturity groups, with the coefficient of determination (r2) ranging from 0.94 to 0.97.
Fernanda Vieira Santana, Annie Carolina Araújo de Oliveira, Leila Albuquerque Resende de Oliveira, Isabella Cícera Dias Miranda, Caroline de Araújo Machado, Paulo Augusto Almeida Santos, Ana Veruska Cruz da Silva, Ana da Silva Ledo
Hancornia speciosa Gomes, popularly known as mangaba tree, is a fruit tree native to Brazil, with natural occurrence in several regions. However, some factors have contributed to the reduction of natural populations of this species, in addition to the recalcitrant characteristic of its seeds, which hinders their storage for conservation purposes. The application of plant tissue culture techniques is a complementary strategy to the conservation of the existing genetic variability and allows accelerating the multiplication of promising genotypes. This study aimed to evaluate the effect of the desiccation time of mangaba tree on seed moisture and regeneration using cryopreserved and non-cryopreserved embryos. Seeds were extracted from mature and immature fruits of BRA00074140-5 accession, belonging to Mangaba Tree Active Germplasm Bank of Embrapa Tabuleiros Costeiros, Sergipe, Brazil. At 24 hours after seeds extraction, they were desiccated in Magenta ™ boxes containing silica gel (50 g/magenta) for 0, 8, 10, 12, and 14 hours, at room temperature. Seed moisture (four samples of five seeds/maturation) was determined for each desiccation period. After each desiccation period, seeds were inoculated in germination medium (control 2), and two samples of ten seeds for each desiccation time were immediately placed in cryotubes and immersed in liquid nitrogen (-196ºC). For the evaluation of the germination percentage, seeds were thawed in sucrose solution for 24 hours. Subsequently, embryos were excised and inoculated in MS culture medium with 3% sucrose and 0.30% Phytagel® and evaluated at 60 days of culture. Cryopreserved seeds regenerated no embryos. Further studies should be performed to obtain regeneration from cryopreserved seeds.
Wellinghton Alves Guedes, Railene Hérica Carlos Rocha Araújo, Josinaldo Lopes Araújo Rocha, José Franciraldo de Lima, George Alves Dias, Ágda Malany Forte de Oliveira, Robson Felipe de Lima, Luana Muniz Oliveira
Aims: This study evaluates the influence of Spirulina platensis concentrations on the growth and quality of papaya (Formosa Group) ‘Tainung-1’.
Study Design: The experimental design was completely randomised, with plots subdivided over time.
Place and Duration of Study: From April to June 2017, two greenhouse experiments were carried out at the Agro-Food Science and Technology Center of the Federal University of Campina Grande, Pombal-PB, Brazil.
Methodology: We carried out two greenhouse experiments in completely randomised designs, one with the application of S. platensis on the leaf and other with an application on the root. In both experiments, the treatments consisted of six biomass concentrations of S. platensis (0.0, 0.4, 0.8, 1.2, 1.6, 2.0%).
Results: At 52 days after sowing, we measured the following variables: growth, production of dry and fresh mass of roots and shoot, and the seedlings quality index. The modelling functions predict that the suspensions with 1.08% of S. platensis applied on root may provide the best growth and biomass production of the seedlings. However, suspensions of S. platensis applied on leaf were inefficient in the improvement of seedling quality.
Conclusion: When applied to the roots, a suspension of 1.08% S. platensis increases the growth and biomass production of the seedlings; and when used in the concentration of 0.88% improves the quality of the 'Formosa' papaya seedlings. Suspensions of S. platensis applied on leaves do not affect the growth and quality of seedlings of papaya.
Aims: This study aimed at enhancing common bean production among the small holder farmers along the Lake Victoria basin, Kenya through the use of water hyacinth compost.
Study Design: Randomized Complete Block Design with a split-plot structure with three replications. The bean cultivars formed the main plots while fertilizers formed the sub-plots.
Place and Duration of Study: Field trials were conducted on small holder farms in Kisumu, Lake Victoria basin during the short and long rains in 2012/2013.
Methodology: Fresh water hyacinth weeds were cut into smaller pieces and left to completely dry in the sun and allowed to decompose naturally for 45 days. The treatments consisted of control (no fertilizer), water hyacinth compost and diammonium phosphate (DAP) fertilizer (DAP). The fertilizers were applied at the rate of 46 kg ha-1 of DAP or 8 T ha-1 of compost along the rows and thoroughly mixed within the top 15 cm of soil to avoid direct contact with the seeds or the rhizobia inocula.
Results: Water hyacinth compost significantly (P<0.05) increased nodulation and improved yield while diammonium phosphate also enhanced yield but suppressed nodulation of the beans. Other agronomic characteristics such as plant height, number of flowers and pods of beans were not significantly (P > 0.05) influenced with the application of either compost or diammonium phosphate.
Conclusion: Application of water hyacinth compost has the potential for use as an alternative to expensive inorganic nitrogenous fertilizers in restoring soil fertility and improving bean crop productivity in Kenya.
The objective of this study was to determine the influence of lead nitrate (Pb(NO3)2) on the germination and initial development of leucaena (Leucaena leucocephala) and canafístula (Peltophorum dubium). The experimental design was a randomized complete block design in a 2x6x4 factorial scheme [two forest species and six Pb(NO3)2 doses], with 4 replicates per treatment, totaling 48 sample units. Statistical analyzes were performed to analyse the variables: tukey test and regression at 5% probability. The experiment was carried out in August 2015, in the botany laboratory of the Pontifical Catholic University of Paraná (PUCPR), Toledo, Paraná, Brazil. The seeds were conditioned to germinate for 14 days in the presence of Pb(NO3)2 treatments in a germination chamber. At the end of 14 days were determined: total germination, chlorophyll content (a, b, total and chlorophyll a/b ratio), lead (Pb) contents in roots and leaves, as well as morphometric variables: shoot length, radicular and collecting diameter. L. leucocephalawas the species that obtained the highest germination index and higher contents of chlorophyll a, b and total. In the species of P. dubium it was found higher levels of lead in the leaves, in the root system and higher chlorophyll a/b ratio. It was concluded that the doses of Pb(NO3)2 influenced the germination of the initial development of L. leucocephala and P. dubium, L. leucocephala being the species that best tolerated the doses administered. Increasing doses of Pb(NO3)2 influenced germination rates and initial development of L. leucocephala and P. dubium at the end of 14 days after sowing. According to the morphometric evaluations and analysis of lead content in roots and leaves, P. dubium was the species that showed the highest sensitivity in the presence of the doses, indicating the higher resistance of L. leucocephala, affirming its use in recovery of contaminated areas.