Luiz Antonio Augusto Gomes

Inheritance of foliar zingiberene contents and their relationship to trichome densities and whitefly resistance in tomatoes

The sesquiterpene zingiberene, present in leaf glandular trichomes, is reportedly responsible for the high level of arthropod resistance found in Lycopersicon hirsutum var. hirsutum. This paper reports on the inheritance of zingiberene contents and of the various types of glandular trichomes in the interspecific cross L. esculentum × Lycopersicon hirsutum var. hirsutum. Plants of L. esculentum ‘TOM-556’ (= P1), L. hirsutum var. hirsutum ‘PI-127826’(= P2), F1 (P1 × P2) and F2 (P1 ×P2) were evaluated for zingiberene contents and densitities of and glandular (types I, IV, VI and VII) trichomes. Broad sense heritabilities were high for all traits studied (0.678, 0.831, 0.996, 0.799 and 0.717 respectively for zingiberene and trichome types I, IV, VI, VII). There were significant positive genetic correlations between zingiberene contents and densities of trichomes types IV, VI and VII. Inheritance of zingiberenecontents can be explained mostly by the action of a single major locus, inwhich the allele from L. hirsutum that conditions high content is incompletely recessive over the allele from L. esculentum. Action of an incompleteley recessive allele in one major locus appears to be evident for densities of trichome types IV, VI and VII, but there is also evidence of the action of other epistatic loci for types IV and VI. F2 genotypes selected for high zingiberene levels showed higher levels of resistance to the silverleaf whitefly Bemisia argentifolii than L. esculentum ‘TOM-556’, levels that were comparable those found in L. hirsutum var. hirsutum ‘PI-127826’ and other whitefly resistant accessions.

Adubação verde na produção orgânica de alface americana e repolho

The exclusive use of organic compost in the production of organic vegetables has been found to be a costly practice due to the high volume of compost demanded to obtain commercial productions. Thus, one of the alternatives for complementary fertilization of vegetables is the use of green manure. The objective of this work was to evaluate three green manure species, used to complement the fertilization with organic compost, in relation to the nutrient contents in their biomass, and to productivity and agronomic traits of crisphead lettuce and cabbage. The experiment was carried out at the Olericulture Sector of the Federal University of Lavras (UFLA), in Lavras, Minas Gerais State, Brazil, from December 2001 to August 2002, in a soil classified as Udox. The experiment was arranged in a randomized block design in a factorial scheme (4x2) with three repetitions. The first factor was constituted by the green manure species: black-velvet bean (Stizolobium aterrimum), jack bean (Canavalia ensiformis), and sunnhep (Crotalaria juncea), plus a control treatment (weed and mineral fertilizers); and the second factor was constituted by the vegetable crops: crisphead lettuce and cabbage. Among the tested green manure species, sunnhep presented the best potential for extraction of N, P, K, Mg, B, Mn and Zn. In addition, sunnhep was more efficient than jack bean or black velvet bean in increasing the commercial weight of cabbage head. In relation to productivity, as for lettuce, green manuring plus organic compost did not differ from the control; while for the cabbage, these treatments had a performance statistically inferior. The use of green manure plus organic compost allowed to obtain commercial crisphead lettuce and cabbage heads with satisfactory weight for the market.

Híbridos pré-comerciais resistentes a Tuta absoluta obtidos de linhagem de tomateiro rica em acilaçúcares

This experiment was designed to assess the agronomic potential of tomato hybrids obtained from the tomato line TOM-687, an acylsugar-rich line with confirmed resistance to an array of tomato pests. The experiment was carried out at the HortiAgro Sementes research station, in Ijaci, Minas Gerais State, Brazil. The treatments comprised 30 genotypes (5 commercial hybrid checks, 1 high acylsugar line (TOM-687), and 24 hybrids in which TOM-687 was one of the parents). Plants were trained to two stems, in a spacing of 1.30 m between rows x 0.50 m between plants within a row, totaling 15,385 plants per hectare. Nine harvests were performed between November 1st, 2008 and November 28th,2008. Traits assessed were mean fruit weight (g fruit-1) and total yield (t ha-1). All 24 hybrids with TOM-687 as a parent showed yields similar to those of the commercial check hybrids Debora Max, Bravo, Bonus, Kombat and Atyna. Four of these experimental hybrids (TEX-298, TEX-310, TEX-315 and TEX-316) were assessed for resistance to the South American tomato pinworm Tuta absoluta, and were shown to possess higher degrees of pest resistance than the current commercial hybrid checks.

Inheritance of bolting tendency in lettuce Lactuca sativa L.

Resistance to early flowering is an important attribute of lettuce cultivars adapted to tropical conditions. Lettuce cultivars may vary widely in the number of days necessary from sowing to inflorescence formation and flowering. In this paper, we report on the polygenic inheritance of the number of days to flowering in two crosses among contrasting lettuce cultivars – Vitória × Brasil-303 and Babá × Elisa. F1 and F2 seed were obtained for each cross, and used to estimate broad sense heritabilities. F3 families were obtained from randonly sampled F2 plants, and used to estimate narrow sense heritabilities based on parent-offspring regression. Trials were carried out in plastic greenhouses in Campos dos Goytacazes, in the Northern part of the State of Rio de Janeiro, Brazil. Broad and narrow sense heritabilities for days to first anthesis were 0.737 and 0.489 for the cross Vitória × Brasil-303, and 0.818 and 0.481 respectively, for the cross Babá × Elisa. In both crosses, both early and late-flowering transgressive segregants were obtained. Genetic gains based on selection of late flowering transgressive segregants in the F2s were estimated to be 10.2 days in Vitória × Brasil-303 cross, and 8.7 days in the Babá × Elisa cross.

Intra and interlocus interactions between alcobaça (alc), crimson (ogc), and high pigment (hp) loci in tomato Lycopersicon esculentum mill.

The ripening mutant allele alcobaça (alc/alc) may be deployed to extend shelf life in tomatoes, but has reportedly negative effects on fruit colour development. Colour enhancing mutants crimson (ogc/ogc) and high pigment (hp/hp) could potentially overcome this limitation, but a detailed account of their interactions with alc is not available. In this paper, we report on intra-allelic (additive and dominant) interactions within these 3 loci, and on their possible interallelic (epistatic) interactions. Eight near-isogenic (NIL) tomato lines in background Flora-Dade were obtained, representing all possible 2nhomozygous combinations in the n = 3 loci. The 8 NIL were crossed in all possible combinations (reciprocals excluded), to obtain 28 hybrids that were heterozygous in at least one locus. The 36 treatments (= 8NIL + 28 hybrids) were grown in a randomized complete block design with 4replications, and the following traits were evaluated: total yield, average fruit mass, fruit firmness at harvest (= breakerstage) and 6 days after harvest (d.a.h)., % coloured fruit surface, fruit lycopene and beta-carotene contents, fruit % soluble solids and solids/acidity ratio, internal and external fruit colour. The loci alcobaça, crimson and high pigment or their epistatic interactions had significant influence on the expression of all traits measured. Epistatic effects were responsible for most of the variation among genotypes (with a minimum of 48.1%of the total sum of squares for % coloured fruit surface and a maximum of 82.8% for total yield). External fruit colour was defficient in all alc/alc genotypes, and their commercial use is impaired, in spite of improvements in fruit internal and external colour brought about by deployment of specific genotypic constitutions in lociogc and hp. Some but not all alc+/alc genotypes were firmer and showed improved fruit quality over the normal Flora-Dade (alc+/alc+ogc+/ogc+hp+/hp+) background. The following genotypic combinations represented good compromises between yield, long shelf life and fruit quality traits: alc+/alc ogc+/ogchp+/hp, alc+/alc ogc/ogchp+/hp+ and alc+/alc ogc+/ogc+hp+/hp

Correlação entre caracteres e estimação de parâmetros populacionais para batata-doce

Sweetpotato cultivars currently grown were selected essentially for their use in human consumption, with little regard for their other potential uses such as ethanol production or animal feed. The objective of this work was to estimate population parameters and genotypic, phenotypic and environmental correlations associated with these traits. Thirty-nine sweetpotato genotypes from the germplasm bank of the Universidade Federal de Lavras were assayed in a randomized complete block design trial with 2 replications. The estimated genetic (CVg) and environmental (CVe) coefficients of variation, the broad sense heritabilities (ha2) and the b= CVg/CVe ratio favor selection of the majority of the traits analysed, with estimates generally higher than 9.52%, 1.44 and 79.31% for CVg, CVg/CVe and ha2, respectively. For all pairs of traits studied, the genotypic and phenotypic correlations had the same sign, and were similar in both magnitude and level of significance. In the cases where correlations were significant, the estimates of the genotypic correlations were slightly higher than those of the phenotypic correlations, and both were higher than environmental correlations as was observed between total fresh root yield x percentage of dry matter in roots, percentage of dry matter in the leaves+vines x total fresh root yield, mean root shape ratings x general root shape ratings. No genetic or phenotypic correlation was observed beetween percentage of root dry matter and measured root density. The selection and recommendation of sweet potato genotypes based on a set of these studied characteristics (depending on the segment of market to be explored), will make possible the complete use of this precious vegetable genetic resource, and its more intense adoption in national agriculture.

Produção de mudas de alface em substrato alternativo com adubação

Alternative substrates, besides allowing the production of quality seedlings, reduce the production costs. In this work we evaluated the production of lettuce seedlings (Lactuca sativa L.) using mixtures of carbonized rice husk and earthworm humus with different doses of SulPoMag®. The experimental design consisted of complete randomized blocks, with five treatments and four replicates. The evaluated mixtures consisted of treatment 1: 70% of earthworm humus (HM) and 30% of carbonized rice husk (CAC), with 12.2 g of Arad phosphate (FA) per each liter of mixture, and treatments 2, 3 and 4: formulated with the same quantities of HM, CAC and FA, added respectively with 2,0; 4,0 and 8,0 g of SulPoMag®. The commercial substrate Bioplant® (SC) was used as control. The characteristics shoot fresh mass (MFPA), root fresh mass (MFRZ), shoot dry matter (MSPA), root dry matter (MSRZ), content of shoot dry matter (TMSPA), content of root dry matter (TMSRZ) and electrical conductivity (CE in dS m-1) were evaluated. The commercial substrate and the mixture 1 were superior to the others. Independent of the doses of SulPoMag®, the mixtures did not present differences among them. The mean values of the treatments for MSPA were in the same tendency for MFPA, except for treatment 3, that presented production of MSPA similar to treatment 1 and the commercial substrate. Raising values of the electrical conductivity (CE) were observed in a linear way, in all mixtures, with increasing doses of SulPoMag®. The production of lettuce seedlings is feasible similar to that obtained with the use of commercial substrate, using raw material found in the property. The production of MFPA was negatively affected by the addition of SulPoMag® in the substrate.

Heterose e capacidade combinatória de linhagens de pimentão (Capsicum annuum L.)

Conduziu-se este trabalho com os objetivos de avaliar a capacidade combinatoria de linhagens-elite de pimentao, identificar combinacoes hibridas superiores quanto a produtividade e qualidade de frutos, e inferir sobre os modos de acao genica envolvidos na expressao dos caracteres de importância economica. Para isso, foram realizados cruzamentos dialelicos para obtencao de hibridos, os quais foram analisados segundo o esquema dialelico parcial tipo North Carolina II, estimando-se as capacidades geral (CGC) de cada genitor dentro de cada grupo, bem como as capacidades especificas (CEC) de combinacao para cada combinacao de genitores. Os hibridos experimentais apresentaram heterose para producao total e massa media de fruto. A caracteristica producao precoce e condicionada, predominantemente, por alelos recessivos. Os melhores hibridos, com perspectivas para uso comercial, foram F1 (L-3436 x L-004), F1 (L-3513 x L-004) e F1 (L-3509 x L-004). Foram obtidos valores positivos de heterose padrao variando de 7,50 a 49,89% para producao precoce, de 0,45 a 28,55% para producao total, e de 3,07 a 47,37% para massa media de fruto, em relacao a cultivar-padrao Magali-R F1.

Avaliação de populações F2 de alface quanto à resistência aos nematóides das galhas e tolerância ao florescimento precoce

No presente trabalho avaliou-se e selecionou-se plantas resistentes aos nematoides das galhas (Meloidogyne spp) e tolerantes ao calor quanto ao florescimento, a partir de oito populacoes F2 de alface. Em um primeiro experimento, fez-se a avaliacao para nematoides das galhas. Alem das oito populacoes F2, utilizaram-se como testemunhas as cultivares Regina 71 (suscetivel) e Grand Rapids (resistente). De acordo com uma escala de notas de 1 a 5, referentes a incidencia de galhas nas raizes de cada planta, estabeleceu-se um ponto de truncagem baseado no numero de plantas das cultivares Regina 71 e Grand Rapids para cada nota, que no caso foi a nota 2. Plantas das populacoes F2 com notas 1 e 2 foram consideradas resistentes, sendo selecionadas. Tomaram-se aleatoriamente 80 plantas de cada populacao, entre as selecionadas, e das cultivares Regina 71 e Grand Rapids, as quais foram transplantadas para estufa. Avaliou-se nesta etapa, o numero de dias decorridos da semeadura ate a primeira antese em cada planta, obtendo-se a distribuicao de frequencia das plantas da cultivar Regina 71 (tolerante ao florescimento precoce) e Grand Rapids (suscetivel ao florescimento precoce). Estabeleceu-se da mesma forma que no experimento anterior, um ponto de truncagem, que neste caso foi de 111 dias. Este numero foi utilizado como limite minimo para selecao de plantas tolerantes ao florescimento precoce. Foi possivel selecionar 13,46% das plantas, que floresceram a partir dos 111 dias, as quais ja haviam sido selecionadas para resistencia a nematoides. O efeito aditivo e a herdabilidade alta para o carater de resistencia a nematoides, assim como para a tolerância ao pendoamento precoce, permitem antever a possibilidade de obtencao de linhagens superiores, a partir de plantas selecionadas para estas caracteristicas.

Alcobaça ALLELE AND GENOTYPIC BACKGROUNDS AFFECT YIELD AND FRUIT SHELF LIFE OF TOMATO HYBRIDS

Post-harvest shelf life of tomato fruit may be increased by deploying mutant alleles which affect the natural ripening process and/or by a favorable genotypic background. Among the several ripening mutant genes, alcobaca (alc) has proved to be highly efficient in increasing shelf life of commercial tomato fruits, especially in heterozygosis, a state at which no limiting deleterious effects upon fruit color occur. The effects of heterozygosity in the alcobaca locus (alc+/alc) on yield and fruit quality traits of tomato hybrids with three genotypic backgrounds. We evaluated three pairs of hybrids obtained from crosses between the near-isogenic pollen source lines Flora-Dade (alc+/alc+) and TOM-559 (alc/alc), and three maternal lines (Stevens, NC-8276 and Piedmont). The six treatments were factorial combinations of two different status in the alc locus (alc+/alc and alc+/alc+) versus three different genotypic backgrounds (maternal lines). Fruits were harvested at the breaker stage of maturation and stored in shelves at 21oC for 14 days. Yield and fruit quality traits were then evaluated. Regardless of the background, the alc allele in heterozygosis (alc+/alc) did not interfere with the total yield, commercial yield, average mass per fruit, average mass per commercial fruit, fruit shape, or with fruit peduncular scar diameter. The alc+/alc genotype reduced the rate of firmness loss and delayed evolution of the red color of the fruit, thus contributing to an increase of the post-harvest shelf life for all three genotypic backgrounds.