Genetic parameters for drought-tolerance in cassava

The objective of this work was to evaluate the effect of drought on genetic parameters and breeding values of cassava. The experiments were carried out in a completely randomized block design with three replicates, under field conditions with (WD) or without (FI) water deficit. Yield of storage roots (RoY), shoot (ShY), and starch (StY), as well as the number of roots (NR), and root dry matter content (DMC) were evaluated in 47 cassava accessions. Significant differences were observed among accessions; according to heritability, these differences had mostly a genetic nature. Heritability estimates for genotypic effects () ranged from 0.25±0.12 (NR) to 0.60±0.18 (DMC), and from 0.51±0.17 (NR) to 0.80±0.21 (RoY and StY) for WD and FI, respectively, as a consequence of greater environmental influence on WD. Selective accuracy was lower in WD, and ranged from 0.71 (NR) to 0.89 (RoY, DMC, and StY). However, genetic gains were quite high and ranged from 24.43% (DMC) to 113.41% (StY), in WD, and from 8.5% (DMC) to 75.70% (StY) in FI. These genetic parameters may be useful for defining which selection strategies, breeding methods, and experimental designs are more suitable to obtain cassava genetic gains for tolerance to drought.

Comparative study of the mandarin hybrid fruit characteristics: Nova, Murcott and Ortanique in Capão Bonito SP, Brazil

The Murcott tangor represent 20% of the tangerines trees in São Paulo State being the second more grown. Their fruits have good acceptance in the market cause of the good characteristics presented as: size, attractive internal and external color, transport resistance, high juice rate and industry potential. It is necessary to study the behavior of others varieties, in order to amplify the diversity of tangerine industry, which show suitable characteristics to the fresh fruit market and that make possible different harvest season. Many tangerine varieties, selected from the Citrus Germplasm Bank of the do Centro Avançado de Pesquisa Tecnológica do Agronegócio de Citros "Sylvio Moreira"/IAC, belong to trials carried out in 15 places in São Paulo State. The Capão Bonito area, south-west of the state, is one of this places where the Nova tangelo, the Ortanique and the Murcott tangors are showing quite good results about their fruit qualities. This paper had as an objective to compare the fruit characteristics of the Nova tangelo, the Murcott and the Ortanique tangors grafted on two rootstocks: Rangpur lime and Cleopatra mandarin. Accordingly to the gotten results, is possible to conclude that Nova and Ortanique had shown weight, width, fruit shape and juice percent, similar to the Murcott. In compliance with the harvest season, the Nova present suitable conditions to fresh fruit market in May and June. By the other hand the Murcott fruits can be harvested in July to August and the Ortanique in August to September. For this reason, is possible extend the harvest season of this mandarin-like, from two to five month, occurring inclusive in a period out of the crop at the north hemisphere.

Effects of biofilm and refrigeration on acerola postharvest conservation

The objective of this work was to compare the effects of four different concentrations of cassava starch film and storage temperature on shelf life and the quality of a genotype of acerola from the Germplasm Active Bank (GAB) of Federal Rural University of Pernambuco, Brazil. Sound orange-reddish acerola fruits were washed with a chlorine solution (100 mg.L-1 active chlorine) and randomly distributed into different lots. The fruits were dipped for 3 min in a cassava starch suspension with concentrations of 1, 2, 3 and 4% (w/v) and the control without coating, stored at 10ºC (85% RH) and 22ºC (85% RH). The total soluble solids (TSS), pH, titratable acidity (TA) and ascorbic acid (AA) were determined at harvest and regular interval during storage. The use of cassava biofilm at 1% on acerola fruits maintained the highest ascorbic acid content and the temperature of 10ºC extended storage life. The fruits coated with 1 and 2% biofilm could be stored for a period up to 15 days at 10ºC, with acceptable quality characteristics.

Characterization of sour (Prunus cerasus L.) and sweet cherry (Prunus avium L.) varieties with five isozyme systems

Extracts from young leaves of nine sweet cherry (Prunus avium L.) and eight sour cherry (Prunus cerasus L.) varieties, located in the germplasm collection of the 'Direção Regional de Agricultura da Beira Interior' (Fundão, Portugal), were analysed for five isozyme systems in order to characterise these varieties and detect problems of synonymies and homonymies that frequently present. The sweet and sour cherry varieties analyzed showed low isoenzymatic polymorphism, being PGM and PGI the systems with the highest discrimination power. These systems presented seven and five different zymogrames, respectively. IDH showed four patterns. SKDH and 6-PGD grouped the varieties only into two patterns. The evident and discriminant restrictions of this type of analysis had got results that have only been a complement for agronomical and morphological characterization.

Diversity and genetic struture in cajá tree (spondias mombin l.) populations in northeastern Brazil

Spondias mombin L. is a fruit tree from the American continent from the Anacardiaceae family. In Brazil it is common in different vegetation types but is more frequent in the Atlantic and Amazonian rainforests. It is economically important because of its fruits, which are widely consumed raw or processed as fruit jellies, juices and ice creams. The leaves have great importance in the pharmaceutical industry because of their antibacterial properties. In the state of Pernambuco, cajá tree is widely distributed in the Zona da Mata region and less frequently in the Agreste and Sertão areas. In this work diversity and genetic structure were studied in four populations of cajá tree from Pernambuco's Zona da Mata, Northeast Brazil, using isozymes polymorphism analyses from electrophoreses. The result showed 100% of polymorphism (P) for nine alleles and the average of alleles per locus s was 2.4. The expected heterozygosity ranged from 0.530 to 0.574 and the observed heterozygosity , from 0.572 to 0.735. It was not observed inbreeding and the average F IT was -0.175, whereas within population inbreeding (f) varied from -0.08 to- 0.37. The genetic divergence among the populations (F ST) ranged from 0.006 to 0.028 and the average was 0.026. The average of estimated gene flow (Nm) was high (5.27). The CG-IPA population, corresponding to the germplasm collection of IPA, showed more than 96% of genetic similarity with other populations; therefore, it is a good representative of the existent genetic diversity in the Zona da Mata region.

Residual effect of growth regulators in etiolation and regeneration of in vitro pineapple plants

This work aimed to evaluate the influence of naphthaleneacetic acid (NAA) and gibberellic acid (GA3) plant regulators in in vitro etiolation and subsequent regeneration of the PE x SC-60 pineapple hybrid. Nodal segments of in vitro plants with approximately 5-7 cm height were incubated in basic MS culture medium supplemented with 0.0; 0.5 and 1.0 mg L-1 of naphthaleneacetic acid (NAA) in combination with gibberellic acid (GA3) in concentrations of 0.0; 0.5 and 1.0 mg L-1, and maintained at 27 ºC under dark condition. Evaluations were carried out at 90 and 180 days after incubation period. The best results for length of etiolated stems were obtained with 1.0 mg L-1 of NAA. In the experiment followed by the regeneration, stems with 3 cm from the etiolation treatment, were cultivated in proliferation medium and the number of regenerated plants per treatment was evaluated at 60 days of cultivation. The treatment that promoted the best etiolation of plants also promoted the worst regeneration rates, demonstrating the residual effect of the auxin used in the previous step in the regeneration of plants of the pineapple hybrid evaluated.

Genetic dissimilarity among jabuticaba trees native to southwestern Paraná, Brazil

Knowledge on the genetic diversity within and between genotype groups is of great importance for breeding programs. The purpose of this study was to estimate the genetic dissimilarity among 36 native jabuticaba trees (Plinia cauliflora) from five sites in the southwestern region of Paraná, Brazil. Sixteen fruit traits were analyzed, based on multivariate techniques (canonical variables, Tocher and UPGMA), using Mahalanobis' distance as dissimilarity measure. By the techniques of clustering and graphic dispersion, together with the comparison of means, the genetic diversity among native jabuticaba trees was efficiently identified, indicating a high potential of these genotypes for breeding programs. The traits of greatest importance for dissimilarity were percentage of pulp and of skin, which are easily measured. The clustering structure is related to the collection sites and for breeding programs, genotypes from different sites should be crossed to generate progenies to be tested. Genotypes 'CV5' and 'VT3' should be conserved in genebanks, due to its important agronomic traits.

Molecular characterization of papaya genotypes using AFLP markers

Due to the low genetic variability reported in the commercial plantations of papaya (Carica papaya L.), the objective of this study was analyze the genetic diversity of 32 genotypes including cultivars, landraces, inbred lines, and improved germplasm using the AFLP technique (Amplified Fragment Length Polymorphism). The genetic distance matrix was obtained using the Nei and Li genetic distance and clustering was performed using the unweighted pair-method with arithmetic mean (UPGMA). Using 11 combinations of EcoRI/MseI primers, 383 polymorphic bands were obtained. On average, 34.8 polymorphic bands were obtained per primer combination. Five clusters were formed. The traditional cultivar 'Sunrise' and the inbred line CMF-L30-08 were the closest genotypes, and the improved germplasm (CMF041) and landrace (CMF233) the most distant. The main papaya cultivars commercially grown in Brazil, as well as four inbred lines and three improved germplasm, were clustered together, however, were not grouped in the same branch. The genetic distance between the Sunrise and Golden cultivars was 0.329, and even arising from mutation and selection within the Sunrise variety, the Golden stores considerable genetic variability. Additional variability was observed in the inbred lines derived from papaya breeding program at Embrapa Cassava and Fruits.

Diversity and genetic relatedness among genotypes of Vitis spp. using microsatellite molecular markers

The purpose of this research was to study the genetic diversity and genetic relatedness of 60 genotypes of grapevines derived from the Germplasm Bank of Embrapa Semiárido, Juazeiro, BA, Brazil. Seven previously characterized microsatellite markers were used: VVS2, VVMD5, VVMD7, VVMD27, VVMD3, ssrVrZAG79 and ssrVrZAG62. The expected heterozygosity (He) and polymorphic information content (PIC) were calculated, and the cluster analysis were processed to generate a dendrogram using the algorithm UPGMA. The He ranged from 81.8% to 88.1%, with a mean of 84.8%. The loci VrZAG79 and VVMD7 were the most informative, with a PIC of 87 and 86%, respectively, while VrZAG62 was the least informative, with a PIC value of 80%. Cluster analysis by UPGMA method allowed separation of the genotypes according to their genealogy and identification of possible parentage for the cultivars 'Dominga', 'Isaura', 'CG 26916', 'CG28467' and 'Roni Redi'.

Heterosis in papaya: inter and intragroup analysis

Papaya (Carica papaya L.) is a typical crop of tropical areas, and Brazil is one of the leading world producers. In recent decades, papaya culture has expanded to different regions of the country, but the number of cultivars available is still limited. In the present study, a complete diallel cross was carried out using eight accessions of papaya from the UENF/Caliman germplasm bank. Four genotypes belong to the Formosa heterotic group and four, to the Solo group. This study aimed to evaluate the occurrence and viability of exploring heterosis in heterotic intragroup hybrids. Fifty-six hybrid progenies were generated and evaluated. Among the Formosa intragroup hybrids, two hybrid combinations (MR x J4 and MR x SK) showed heterosis for all traits, as well as good average total fruit production. Among the Solo intragroup hybrids, three hybrid combinations (WM x GG, WM x SS and WM x SM) stand out for fruit production and high content of soluble solids. In Formosa x Solo hybrids, all hybrid combinations with the parent JS (JS x WM, JS x GG, JS x SS and JS x SM) showed high fruit quality and good average for fruit production. The heterotic profile of the hybrids tested allowed the identification of promising hybrids within Formosa and Solo heterotic groups. The analysis of the canonical variables also allowed the visualization of distinct groups of hybrids, depending on the provenance of the parents.

Seleção de genótipos de soja resistentes a duas estirpes de Soybean mosaic virus

Soybean mosaic virus (SMV) is the most prevalent virus on soybeans (Glycine max) throughout the world. It causes mottling on seeds and has been associated with yield reduction. Recently, a new strain (SMV 95-1) was found infecting resistant cultivars, causing dwarfing and systemic necrosis. In a screening test carried out with the strains SMV 95-1 and SMV 95-2 on the germplasm collection, several resistant cvs. Embrapa 60, Embrapa 61, Embrapa 62, Embrapa 66 , Embrapa 133, Embrapa 134, Embrapa 135, and Embrapa 136 were identified as resistant to both strains. The resistant genotypes may serve in future soybean breeding programs in Brazil.

RT-PCR and Dot Blot hybridization methods for a universal detection of tospoviruses

Transcriptase reverse - polymerase chain reaction (RT-PCR) and dot blot hybridization with digoxigenin-labeled probes were applied for the universal detection of Tospovirus species. The virus species tested were Tomato spotted wilt virus, Tomato chlorotic spot virus, Groundnut ringspot virus, Chrysanthemum stem necrosis virus, Impatiens necrotic spot virus, Zucchini lethal chlorosis virus, Iris yellow spot virus. Primers for PCR amplification were designed to match conserved regions of the tospovirus genome. RT-PCR using distinct primer combinations was unable to simultaneously amplify all tospovirus species and consistently failed to detect ZLCV and IYSV in total RNA extracts. However, all tospovirus species were detected by RT-PCR when viral RNA was used as template. RNA-specific PCR products were used as probes for dot hybridization. This assay with a M probe (directed to the G1/G2 gene) detected at low stringency conditions all Tospovirus species, except IYSV. At low stringency conditions, the L non-radioactive probe detected the seven Tospovirus species in a single assay. This method for broad spectrum detection can be potentially employed in quarantine services for indexing in vitro germplasm.

Screening of sweet sorghum accessions for inhibition of secondary sporulation and saccharide measurements in honeydew of Claviceps africana

Certain sweet sorghums (Sorghum bicolor) inhibit the secondary sporulation of Claviceps africana, which occurs on exuded ergot honeydew when the parasite is supplied with excess sucrose, which is then transformed to unique free oligosaccharides fructosyl - mannitol and difructosyl - mannitol with spore germination inhibiting properties. Five accessions (BRA-035726-SUGAR DRIP, BRA-035696-THEIS, BRA-036013-MN-4578, BRA-035947-MN-4418 and CMSXS-633) of sweet sorghum were selected among 50 evaluated. These five accessions failed to support secondary sporulation on the "honeydew" exuded from infected florets. There was a higher concentration (%w/v) of the free oligosaccharides on the honeydew of these accessions when compared to a hybrid male-sterile grain sorghum. Therefore, a possible strategy would be seek to incorporate a sweet character into "A" lines for hybrid seed production in order to restrict secondary disease spread.

Deposição e acúmulo de matéria seca e nutrientes em serapilheira em um bosque de sabiá (Mimosa caesalpiniifolia Benth.)

A quantificação da deposição de serapilheira e o acúmulo de manta orgânica são etapas importantes dos estudos de ciclagem de nutrientes. Com esse fim, objetivou-se quantificar a deposição de serapilheira e o acúmulo de manta orgânica em um povoamento de Sabiá (Mimosa caesalpiniifolia Benth.), no campo experimental pertencente à Empresa Pernambucana de Pesquisa Agropecuária - IPA, Itambé, PE. Para quantificação da serapilheira foram utilizados 20 coletores de madeira de 0,50 x 0,50 x 15 cm, à distância do solo de 30 cm, distribuídos sistematicamente na área. O material depositado foi coletado mensalmente no período de outubro/2000 a setembro/2001. O material colhido em cada coletor foi separado em folhas, galhos, flores, frutos e miscelânea. A manta orgânica não decomposta sobre o solo foi amostrada, ao acaso, nas proximidades da caixa coletora, obtendo-se 20 amostras mensais. De cada amostra foi retirado o material contido numa área de 30 x 30 cm. O material colhido foi separado em folhas, flores, frutos, miscelânea e galhos. As amostras foram levadas à estufa a 60 º C no período de 48 horas até peso constante. A deposição mensal de serapilheira e frações folha e legume ocorreu em outubro, provavelmente devido ao início do período seco. A deposição e o estoque de serapilheira foram estimados em 7830,44 kg.ha-1.ano-1 e 8906.9, kg.ha-1, respectivamente, com a fração folha dominando. A fração folha apresentou os maiores teores de nutrientes.

Caracterização morfológica de frutos e sementes e desenvolvimento pós-seminal de Tamarindus indica L. - Leguminosae: caesalpinioideae

O tamarindeiro (Tamarindus indica L.) pertence à família Leguminosae e é uma árvore frutífera, nativa da África tropical, de onde se dispersou por todas as regiões tropicais do mundo. A caracterização morfológica de frutos e sementes é importante para identificação das espécies, bem como serve de base para estudos que visem a maiores conhecimentos ligados à germinação e vigor. Este trabalho teve por objetivo descrever a morfologia de frutos, sementes e plântulas, bem como caracterizar o processo germinativo de Tamarindus indica L. Para o estudo do fruto, foram observados tipo, cor, dimensões, textura e consistência do pericarpo e deiscência e número de sementes por fruto. Os aspectos observados nas sementes foram: cor, dimensões, textura e consistência dos tegumentos; e forma, borda, posição do hilo e de outras estruturas presentes e características do embrião. O estádio de plântula foi considerado quando os protófilos já estavam totalmente formados. Os elementos vegetativos descritos e ilustrados foram radícula, coleto, hipocótilo, cotilédones, epicótilo, protófilos e caule. O fruto de Tamarindus indica é um legume indeiscente medindo aproximadamente 7,3 a 9,2 cm e contendo de 1 a 11 sementes. O eixo embrionário encontra-se inserido nos cotilédones, sendo axial e invaginado. A germinação da semente é do tipo epígea. A plântula apresenta protófilos compostos de seis a nove pares de folíolos pequenos opostos e glabros.