No abstract

The cowpea is the most important legume in the Colombian Caribbean, due to its positive impact on the food and nutritional security of low-income rural families. It is cultivated by small producers, but its yields per hectare do not exceed 600 kg, due to the use of obsolete cultivars. The objective of the research was to estimate the correlations between seven quantitative characters and the path analysis between grain yield and six quantitative characters, with the results of the evaluation of 10 genotypes of semi-prostrate growth habit, high grain yield, grown in eight environments of the humid and dry tropics of the Colombian Caribbean region, under the randomized complete blocks design, with four repetitions. Significant differences between environments, genotypes and genotype x environment interaction were detected. Genotypic correlations were of greater magnitude than phenotypic, highlighting the correlation between grain width (GW) and grain yield (GY), rP = 0.69 *, rG = 0.78 *, also between the weight of 100 seeds (100SW) and GW, rP = 0.97 **, rG = 0.99 **. The characters GW and number of pods per plant (NPP) had positive direct effects on the GY, with an indirect negative effect of NPP by way of GW, while the height of the first pod (HFP), the number of seeds per pod (NSP) and the 100SW directly and negatively influenced the GY of the 10 semi-prostrate cowpea cultivars.

Cowpea beans are the most important legume in the Caribbean region of Colombia. This grain is produced mainly by small farmers in rural agriculture but is becoming more important every year for commercial agriculture. The objective of this study was to estimate heritability, genetic gain and correlations between agronomic characteristics and the nutritional content of 30 cowpea bean cultivars. The number of days to flowering (NDF), number of pods per plant (NPP), number of pods per peduncle (NPPE), peduncle length (PEL), number of nodes on main stem (NNMS), grain length (GL), grain width (GW), weight of 100 seeds (W100S), iron content (FeC), zinc content (ZnC), protein content in percentage (PROT) and YIELD were evaluated. Likewise, the genetic parameters: phenotypic coefficient of variation (PCV), genotypic coefficient of variation (GCV), variability index (b), heritability [(h2 (%)], genetic gain (GG) and genetic progress (%), together with phenotypic correlations and genetic correlations, were determined. Genetic variability was evidenced in the population (P<0.05), except for PEL. The highest heritability was in W100S, ZnC and FeC (h2A> 96%). The greatest advance was achieved in ZnC, FeC, W100S and YIELD, with values higher than 30%, indicating the potential use of the evaluated genotypes for improving this species and positive and significant phenotypic and genotypic correlations between YIELD and PROT. Therefore, cultivars with higher yields and protein contents can be obtained.

Schizolobium parahyba is a fast-growing tropical tree, with various uses: forestry, agroforestry, landscaping, boat building, cabinetmaking and light packaging. Studies of morphometry and viability of forest species seeds are important for their identification, conservation and sustainable use. The objective of the study was to describe the morphometric and viability characteristics of the seeds of S. parahyba. Free seed pollination of plantations from three locations in Tierralta (Córdoba - Colombia) was used. In each plantation, five trees were randomly taken and, of each, 100 seeds to estimate the morphometric characteristics and seed weight. The morphological description was made with a sample of 10 seeds. The viability was determined by the tetrazolium test in an experiment under a completely randomized design, with six treatments and four replicates of 25 seeds each. The six treatments corresponded to the combinations of three concentrations of tetrazolium (0.5; 1.0 and 1.5%) and two staining times (2 and 3 hours). The width, length, and ratio width / length of the seed showed little variation, compared to the freshweight of a seed, freshweight of 100 seeds and number of seeds per kilogram. Tetrazolium and germination tests showed similar and reliable results. The concentration of 0.5% tetrazolium, with immersion of 2 hours, was sufficient to determine the viability of seeds of S. parahyba.

Drought modifies plant development and generates losses in agricultural production. The aim of this study was to analyze the growth, biomass distribution, gas exchange, and chlorophyll fluorescence in nine cowpea (Vigna unguiculata) genotypes under drought conditions in the greenhouse condition. A completely randomized experimental design with four replicates was used. The following genotypes (treatments) of LC-006-016, LC-029-016, LC-036-016, LC-021-016, LC-005-016, LC-009-016, LC-014-016, LC-002-016, and Caupicor-50 (control) were evaluated with irrigation for 21 days (after sowing) and 38 days of drought (DD) for a total duration of 59 days. In a simultaneous experiment, other plants of the same genotypes were irrigated for 59 days after sowing (DAS) with replacement of evapotranspirated water every three days. Measures of plant height and number of leaves were taken every four days, biomass at 59 days, gas exchange every seven days and chlorophyll fluorescence at 17, 21 and 38 DD. Moisture losses were quantified by recording the loss of soil weight every three days. The results showed that plant height reached 72.2% lower in plants under drought, while the vegetative biomass decreased by 76.3%. The photosynthesis, stomatal conductance, and transpiration were decreased 64.6%, 93.1%, and 86.9% under drought, respectively. Furthermore, intrinsic water use efficiency (A/gs) was increased almost six times. However, it was decreased when drought progressed towards the soil water content loss more than 0.0827 g.g-1. The quantum yield of photosynthesis (ΦPSII) was decreased 28.4%, 40.3% and 43.5% at 17, 21 and 38 DD, respectively, under drought condition. The principal component analysis (PCA) suggests that the genotypes with higher A/gs and those with higher biomass production show greater resistance to drought.