We evaluated the genetic variability of a collection of Jatropha curcas germplasm, represented by 93 accessions, using microsatellite markers. Among the 60 markers tested, five of them detected polymorphisms, with a total of 11 alleles and mean of 2.2 alleles per loci. These five markers enabled the quantification of genetic variability through estimates of expected (He=0.42) and observed (Ho=0.64) heterozygosity, Shannon-Weaver index (H'=0.62), coefficient of inbreeding (ƒ=-0.44) and the formation of 11 clusters. Simultaneously, 14 accessions randomly sampled among the 93 and represented by seven plants each, were analyzed with these same five markers to quantify the within and between variability. Most of the genetic variation (92.58%) was contained within the accessions. These analyses revealed, for the first time, expressive genetic variability to be explored in this collection. The accessions UFVJC 05, 07, 12, 18, and 53 presented expressive variability among them with potential for the constitution of a base population for the breeding program.

Crambe is a potential oilseed plant, which has been suggested for cultivation as a cover crop in the Brazilian Savanna where acidic soils predominate. Understanding of its performance in those conditions is essential. Thus, the objective of this study was to characterize the morphological and physiological changes in crambe plants when subjected to Al exposure at different dose levels. Plants were allocated to a nutrient solution with Al treatments at concentrations of 0.0, 0.1, 0.2, 0.3 and 0.4 mmol L-1. The following parameters were determined: length of root (LR) and shoot (LS), dry mass of roots (RDM) and shoots (SDM), Al uptake in plant tissues, leaf area (LA), absolute growth rate (AGR), grain yield (GY), net CO2 assimilation rate (A), stomatal conductance (gs), transpiration rate (E) and chlorophyll α fluorescence. The experimental design was completely randomized, consisting of five treatments with four replications. Regression analyses of growth parameters and mean comparative tests of physiological traits were performed. Roots concentrated approximately 40-fold more Al than shoots. There was a linear reduction in LS and LR with increasing doses of Al. For RDM, SDM, LA, AGR and GY, the reductions were similar and were better explained by quadratic models. Al damaged the photosynthetic apparatus of crambe plants, demonstrated by a significant reduction in the values of Fv/Fm (estimation of photosynthetic efficiency), A, gs and E, compared to the control. Al negatively affected growth parameters as well as the photosynthetic response of crambe plants, resulting in a substantial decrease in its grain yield.

Methodologies for imposing stress and reproducible results are a bottleneck for breeding programmes, and this is due to the lack of consensus between the existing methodologies. The aim of the present study was to propose and validate a new methodology for imposing water deficit in soybean that allows the identification of water deficit-tolerant genotypes, at different harvest times and phenological stages.The methodology was based on the construction of a water retention curve in the soil to determine the water stresses that indicate the field capacity and the permanent wilt point and, thus, define the water regime in the conditions of control and stress. Seven trials were carried out to validate the methodology. In trials 1, 2, 3, 4, 5 and 6, the water deficit was imposed in the reproductive phase and the components of production were evaluated. In addition to these variables, leaf water potential was evaluated in trial 6. In trial 7, the plants were subjected to water deficit in the vegetative phase and the morphological traits were evaluated. The efficiency of the methodology was confirmed by the distinction between the conditions of control and stress, affirmed by the statistical differences in most of the traits evaluated in the reproductive and vegetative phases.

Crambe is an oilseed plant producing oil that can be used for various industrial purposes, including the production of biofuel. It is a short-cycle, non-food plant that can be grown as a second crop following soybean or corn crops and using the same agricultural machinery. This work aimed to estimate genetic parameters and correlations between traits of genotypes grown for two years in seven locations in two Brazilian states. The cultivar FMS Brilhante and the lines CR 1101, CR 1102, CR 1105, CR 1202, CR 1303, and CR 1304 were used. The traits evaluated were grain yield (YD), plant height (PH), stem diameter (SD), first fruiting branch height (BH), 1,000-seed weight (SW), and number of branches (NB). The correlations between traits were identified from the phenotypic covariance matrix through path analysis. Based on the joint analysis, the interaction of genotypes x years x locations was observed. Expressive genetic variability was verified for all evaluated traits, which allows gains to be made with the selection of genotypes. High broad-sense heritabilities based on plot means were verified for YD, BH, and SW (82, 84 and 77%, respectively), which indicates the possibility of directly selecting them. SW and SD showed the greatest direct effects and strongest correlations with YD.

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