Tomato plant inheritance of antixenotic resistance to tomato leafminer

The objective of this work was to determine the inheritance of resistance by antixenosis in tomato plants (Lycopersicon esculentum) to tomato leafminer [Tuta absoluta (Lepidoptera: Gelechiidae)]. Evaluations were performed for tomato plants of the generations P1, P2, F1, F2, RC1 and RC2. The measured characteristic in the parents, BGH-1497 (P2 male) and 'Santa Clara' (P1 female), and in the F1, F2, RC1 and RC2 generations was the number of eggs per plant. This number was converted to the oviposition nonpreference index. The inheritance of antixenosis resistance of genotype BGH-1497 is ruled by a gene of greater effect and polygenes in epistatic interactions, with a phenotypic proportion of 13:3 between susceptible and resistant genotypes, respectively.

Genotype by environment interaction for seed yield per plant in rapeseed using AMMI model

The objective of this study was to assess genotype by environment interaction for seed yield per plant in rapeseed cultivars grown in Northern Serbia by the AMMI (additive main effects and multiplicative interaction) model. The study comprised 19 rapeseed genotypes, analyzed in seven years through field trials arranged in a randomized complete block design, with three replicates. Seed yield per plant of the tested cultivars varied from 1.82 to 19.47 g throughout the seven seasons, with an average of 7.41 g. In the variance analysis, 72.49% of the total yield variation was explained by environment, 7.71% by differences between genotypes, and 19.09% by genotype by environment interaction. On the biplot, cultivars with high yield genetic potential had positive correlation with the seasons with optimal growing conditions, while the cultivars with lower yield potential were correlated to the years with unfavorable conditions. Seed yield per plant is highly influenced by environmental factors, which indicates the adaptability of specific genotypes to specific seasons.

Gas exchange rates, plant height, yield components, and productivity of upland rice as affected by plant regulators

The objective of this work was to evaluate gas exchange rates, plant height, yield components, and productivity of upland rice, as affected by type and application time of plant growth regulators. A randomized block design, in a 4x2 factorial arrangement, with four replicates was used. Treatments consisted of three growth regulators (mepiquat chloride, trinexapac-ethyl, and paclobutrazol), besides a control treatment applied at two different phenological stages: early tillering or panicle primordial differentiation. The experiment was performed under sprinkler-irrigated field conditions. Net CO2 assimilation, stomatal conductance, plant transpiration, and water-use efficiency were measured four times in Primavera upland rice cultivar, between booting and milky grain phenophases. Gas exchange rates were neither influenced by growth regulators nor by application time. There was, however, interaction between these factors on the other variables. Application of trinexapac-ethyl at both tillering and differentiation stages reduced plant height and negatively affected yield components and rice productivity. However, paclobutrazol and mepiquat chloride applied at tillering, reduced plant height without affecting rice yield. Mepiquat chloride acted as a growth stimulator when applied at the differentiation stage, and significantly increased plant height, panicle number, and grain yield of upland rice.

Popping expansion and yield responses of popcorn cultivars under different row spacings and plant populations

The objective of this work was to evaluate the agronomic traits and the popping expansion index of three Brazilian popcorn cultivars under different row spacings and plant populations. The trials were performed during two crop seasons, under field conditions. The experimental design used was a randomized complete block, in a split-split plot, with 27 treatments and four replicates. Treatments were represented in a triple factorial arrangement: three row spacings (0.40, 0.60, and 0.80 m), three plant populations (40,000, 60,000, and 80,000 plants per hectare), and three popcorn cultivars (IAC-TC 01, IAC 12, and Zelia). The increase in plant population causes a reduction in the number of grains per ear, lower prolificacy, and grain weight loss. Cultivar grain yield is affected by row spacing and popcorn plant population. Cultivar IAC 12 shows highest grain yield under row spacings of 0.40 and 0.60 m and plant population between 60,000 and 80,000 plants per hectare. The popping expansion index is not affected by row spacing or plant population.

Plant growth and leaf-spot severity on eucalypt at different CO2concentrations in the air

The objective of this work was to evaluate the effects of increased air-CO2 concentration on plant growth and on leaf-spot caused by Cylindrocladium candelabrumin Eucalyptus urophylla. Seedlings were cultivated for 30 days at 451, 645, 904, and 1,147 µmol mol-1 CO2 ; then, they were inoculated with the pathogen and kept under the same conditions for seven days. Increased CO2concentration increased plant height and shoot dry matter mass, and decreased disease incidence and severity. Stem diameter was not affected by the treatments. Increased concentrations of atmospheric CO2 favorably affect eucalypt growth and reduce leaf-spot severity.

Optimization of heterologous microsatellites in Piracanjuba

Abstract: The objective of this work was to evaluate 41 microsatellite markers for heterologous amplifications in piracanjuba (Brycon orbignyanus). Some markers were tested for the first time. Loci were optimized for PCR conditions and applied to a sample of 49 individuals. Thirty-one loci resulted in PCR product formation, whereas ten loci yielded intelligible polymorphic patterns in the evaluated sample and can be used for amplifications in this species. From the evaluated markers, four loci (BoM1, BoM13, Bh6, and Bh16) are valid to be applied in the study of piracanjuba.