ABSTRACT The objective of this work was to evaluate the agronomic performance, cooking time and postharvest conservation of roots of sweet cassava clones, to select those superior to the Manteiga variety control, in the Baixo Sul region of Bahia state. A randomized block design in split plot scheme, with three replications was used. Eleven genotypes were evaluated at 10 and 12 months after planting. Considering the mean of two harvests, BRS Kiriris and Saracura showed total root yield (39.85 and 33.91 t ha−1, respectively) and commercial root yield (26.54 and 26.71 t ha−1) that are higher compared to Manteiga (total root yield: 28.06 t ha−1, commercial root yield: 16.95 t ha−1). However, both had cooking time (26.76 and 28.30 min, respectively) higher than that of Manteiga (23.89 min), and BRS Kiriris was unstable regarding the cooking percentage between 10 (91.67%) and 12 months (50%). BRS Aipim Brasil, 2003 14-11, BRS Kiriris, Eucalipto, Saracura and Manteiga were more tolerant to postharvest physiological deterioration. Although some of the evaluated clones presented good performance in the evaluated traits, by analyzing the set of traits, none of them shows sufficient superiority to be indicated as a potential substitute for Manteiga, grown in the Baixo Sul region of Bahia state.

ABSTRACT The storage life of ‘Alexander Lucas’ pear is limited by the occurrence of internal storage disorders during controlled atmosphere (CA). 1-Methylcyclopropene (1-MCP) can be used to delay pear ripening, however, its interaction with CA conditions is not well understood. ‘Alexander Lucas’ fruit were treated with 1-MCP at 300 nL L-1 for 24 h in air at-0.5 or 1.0 °C before being stored. Fruit were kept at-0.5 or 1.0 °C in normal air or CA (2.0 kPa O2 plus <0.7 kPa CO2). After six months of storage, superficial scald did not develop in fruit. The highest incidence of flesh browning (72.2 %) was found in air-stored fruit at-0.5 °C without 1-MCP treatment. Storage in air at 1.0 °C plus 300 nL L-1 1-MCP produced 88.8 % of healthy fruit. In contrast, 1-MCP increased the incidence of flesh and core browning under CA conditions. 1-MCP and CA maintained greener skin color and higher titratable acidity. No significant differences were found for fruit firmness, total soluble solids and ascorbic acid content between the treatments. In conclusion, the quality of ‘Alexander Lucas’ pear was best maintained during six months storage under normal air at 1.0 °C combined with 300 nL L-1 1-MCP treatment.

ABSTRACT This study aimed to validate the artificial hybridization without emasculation in lima beans, identifying F1 generation using microsatellite markers (SSR). We used four accessions from the Active Germplasm Bank of Phaseolus, Universidade Federal do Piauí (BGP-UFPI), with contrasting growth habits and days-to-maturity traits. The 241 crosses performed had a percentage of hybrid pods of 5.8%, obtaining 42 seeds in F1. Artificial cross-fertilization was confirmed by microsatellite markers (BM 211, BM 141, BM 154, and GAT 591), and four plants were identified as hybrids. Thus, the proposed method is effective in performing artificial crosses for lima beans.

ABSTRACT For natural enemies to be effectively used in pest control programs, it is important to understand the basic and applied ecology of an agroecosystem, such as guava orchards in semi-arid regions. We identified the parasitoids associated with the guava psyllid, Triozoida limbata (Enderlein 1918) (Hemiptera: Triozidae), as well as the rates of natural parasitism that occur in a semi-arid region of Minas Gerais State, Brazil. About 130 terminal branches with four leaves fully open and with signs and/or presence of the psyllid were collected from a commercial guava orchard and brought to the laboratory. The material was stored under controlled conditions until the parasitoids emerged. The parasitoids were counted and fixed in 70% ethanol for species identification. In total, 9,897 individuals of T. limbata (adults and immature) and 603 parasitoids were found. The primary parasitoid, Psyllaephagus trioziphagus (Howard, 1885) (Hymenoptera: Encyrtidae), was associated with the guava psyllid, with 4.88% parasitism. Secondary parasitoids Signiphora Ashmead, 1880 (Hymenoptera: Signiphoridae), Aprostocetus Westwood, 1833, and Tetrastichus Haliday, 1844 (Hymenoptera: Eulophidae) were also identified.

ABSTRACT Northern leaf blight caused by Exserohilum turcicum is an important disease of maize (Zea mays L.), and its severity depends more closely on growth lesions than on spot number. Here, we characterized the infection sites of E. turcicum on resistant and susceptible maize genotypes by analyzing the histology of lesions as well as the structural and biochemical mechanisms of infection. Maize leaves were inoculated with the pathogen at specific points and incubated in a microhumidity chamber. Samples were obtained to follow fungal development and host tissue lignification using light and electron microscopy, and the activity and electrophoretic patterns of peroxidases were determined. The time course of spore germination and appressorium formation was essentially the same for both genotypes; however, a delay of 12 h in fungal penetration, accompanied by host tissue lignification, was noted in the resistant genotype, as opposed to that in the susceptible one. Scanning electron microscopy revealed fungal mycelium in the xylem vessels of both genotypes; however, in the resistant genotype, pathogen colonization was restricted to mesophyll cells around the penetration point, where chlorotic flecks were produced. Meanwhile, in the susceptible genotype, following penetration and chlorotic fleck formation, the pathogen continued to grow inside the xylem vessels and profusely colonized mesophyll tissue distant from the penetration point, resulting necrotic lesion development. Electrophoretic patterns of peroxidases were similar between the two genotypes, with three isoenzymes present in all tissues. In addition, two novel isoenzymes were detected in chlorotic flecks, necrotic lesions, and green tissue around the lesions.

ABSTRACT Family farming is important for the production of food for human consumption, but it lacks resources to invest in the soil fertility of its crops. The objective of this study was to analyze whether the use of green manures increases soil fertility in terms of the nutrients N, P and K with low environmental risk for family agricultural production. An experiment was set up in the State of Mato Grosso (Brazil), in randomized complete block design, with a 6 x 3 factorial scheme, four replications, corresponding to 6 types of plants and 3 doses of phosphorus. Leguminous green manure plants were: velvet bean, Crotalaria juncea, Crotalaria ochroleuca and dwarf pigeon pea, in addition to plots with pearl millet and weedy fallow control. Rock phosphate (i.e., reactive natural phosphate) was applied as a source of phosphorus at 0, 50 and 100 kg P2O5 ha-1. The species used as green manure were cut in full bloom and the levels of N, P, K and C in plants and soil were determined. Leguminous green manure plants, after mineralization, increased the stocks of N, P and K in the soil. Crotalaria juncea was the one that reached the highest N accumulation in its constitution, being recommended in the intercropping with species with C/N ratio > 30 to minimize risks of contamination with nitrate in the soil. This work concluded that the managements with green manure plants, especially Crotalaria ochroleuca, are recommended and environmentally safe technical alternatives for family farming.

ABSTRACT Bromeliad Quesnelia quesneliana (Brongniart) L.B. Smith has been reported in the Atlantic Forest, Rainforest, Mesophilic Semideciduous Seasonal Forest, Mangroves and Restingas in the Brazilian southeastern states of Rio de Janeiro and Espírito Santo, but information about their fruit and seed morphology, and germination is limited. The aim of this study was to characterize the external morphology of fruit and seeds, germination rate and post-seminal stages of Q. quesneliana. Fruits were collected from Restinga area in the Armação dos Búzios city, Rio de Janeiro, Brazil. The width and length of fruit and seeds (external morphology) were measured, the post-seminal development of the seeds was analyzed and botanical illustrations were made. The indexes t50, uniformity of germination, mean germination time and germination speed coefficient were also calculated. Germination was assessed for 20 days by counting individuals to obtain the post-seminal stages. Ripe Q. quesneliana fruits are pyriform, reddish-brown in color, with light spots, 26 mm long and 10 mm wide, with an average of 148 seeds per fruit and wrapped in a transparent mucilage. The seeds are 2 mm long and 1 mm wide, with epigeal germination, and its seedlings are cryptocotyledonary. The seeds of this species germinate quickly and have no dormancy.

ABSTRACT The objective of this work was to evaluate the agronomic performance and water use efficiency of crop rotations under conventional system (CTS) and no-tillage system (NTS) through two experiments conducted in the Semiarid region of the northern state of Minas Gerais, Brazil. Experiment 1 consisted of a grain corn-common bean rotation, and experiment 2 consisted of a sorghum-sweet corn rotation. The treatments, in both experiments, consisted of two tillage systems (CTS and NTS) arranged in strip-plots, in two crop years, with ten replications. Yield and production components of all crops and water use efficiency (WUE) of crops grown in the autumn-winter seasons were evaluated within each crop rotation. The data obtained were subjected to analysis of variance and, when significant, the means were subjected to the F test at 5% significance level. The results obtained showed that the NTS increases corn yield in 21.45% in the grain corn-common bean rotation; however, the common bean yield present no difference between tillage systems. NTS increases the sorghum fresh and dry matter yields in 39.65% and 84.26%, respectively, in the sorghum- sweet corn rotation, and the sweet corn total and commercial ear yield in 11.99% and 21.80%, respectively. The NTS increases the WUE of crops grown in the autumn-winter season, in both crop rotations.

ABSTRACT Morphoagronomic characterization is a basic requirement to identify a phenotypic profile of a population. The quantification of variability allows efficient selection of superior and divergent genotypes. Thus, this study aimed to estimate the variability among 490 genotypes and seven strains, from an F2 population of Ricinus communis L., in 35 morphoagronomic traits and 12 agronomic traits. For qualitative descriptors, the entropy technique was used in the percentage frequencies of each category, computing its level using the coefficient of Rényi (1961). Quantitative descriptors were subjected to analysis of variance by the F test, and Tukey test was performed at 1% probability level. Of the morphoagronomic traits used, 13 were related to plants, nine were related to inflorescence, six were related to fruits and seven were linked to seeds, in addition to 12 agronomic traits. The material was arranged in the field with families (strains of five families) interspersed with their respective parents (controls). Stem color, shape and number of racemes collected, main color, type of secondary color and hundred-seed weight have high variability in the population, with formation of 68 groups as a function of genetic similarity. The possibility of selection as to the number of racemes harvested is clear, so it is possible to identify genotypes with higher number, aiming to enhance crop yield.

ABSTRACT The knowledge of genetic diversity in plant population is essential to the success of plant breeding programs. Thus, previous characterization of landraces is one of the first steps before the indication of genotypes to these plant breeding programs. This study aimed to characterize, through morphological traits, and estimate the genetic diversity in landraces of lima bean (Phaseolus lunatus L.). Genetic diversity was estimated by using multivariate methods that selected individual landraces to be indicated for farmers and consumers. According to morphological traits proposed by Biodiversity International, the genotypes UFPI-667 and UFPI- 682 showed higher dissimilarity and high potential to be used in crosses since they are genetically distant and complementary. The principal component analysis identified positive and significant phenotypic associations between variables: pod length, pod width, and grain production. According to the multivariate methods used, the landraces UFPI-666, UFPI-650, UFPI-651, UFPI-687, UFPI-658, UFPI-673, UFPI-667, and UFPI-674 are potential candidates for selection since they have relevant features for lima bean breeding, such as shorter cycles and higher grain production. This study showed that multivariate analysis can be used as an effective tool to find potential traits in lima bean and can assist the lima bean breeders in the selection of potential landraces. Accessions UFPI-667 and UFPI-682 can be indicated as genitors for breeding programs, as they are genetically distant and complementary in their characteristics.