RESEARCH-ARTILE Agricultural performance and genetic parameters for yield-related traits of sugar- and energy cane families derived from planned crosses.

The forecast of a growing energy demand in the coming years has aroused particular interest in biomass for energy cogeneration, to diversify the energy matrix by using clean and renewable sources. To meet the new demands of the sugarcane industry, this study evaluated the agronomic performance and estimated genetic parameters for yield traits in sugar- and energy cane families derived from planned crosses. The cane families were assessed in the northwest of the State of Paraná, county of Paranavaí, in a randomized complete block design, with three replications. The evaluations were carried out 12 months after the first cut, in the ratoon cane cycle, in December 2014, under very unfavorable conditions for the crop, due to the low fertility and water-holding capacity of the soil. Besides, the crop was evaluated at the end of the harvest, when the agricultural and industrial quality of the crop is reduced. The following traits were evaluated at the plot level: soluble solids content, apparent sucrose content (PC), fiber content, tons of cane per hectare, tons of sucrose per hectare (TSH), and tons of fiber per hectare (TFH). High genetic variability was observed for all evaluated traits, with accuracy estimates from 0.69 (TSH) to 0.92 (PC), and high heritability ​​(up to 0.84), indicating the possibility of genetic progress. The sugarcane families derived from crosses of Saccharum spontaneum and Saccharum robustum species with sugarcane hybrids had the highest fiber contents. Highest sugar contents were found in sugarcane families resulting from crosses of sugarcane clones and conventional cultivars. The TSH means were highest in the families F160 x MEX68-200 and RB855156 x RB987935. The highest genotypic mean for TFH was observed in the special polycross involving cultivar RB036066 with S. spontaneum accessions as pollen donors.

Comparison between different selection indices in energy cane breeding.

Sugarcane breeding programs have been adapting to a new market demand: aside from high sucrose yield per hectare, the sector needs new cultivars with higher fiber percentages. The selection of sugarcane clones based on phenotype alone is a complex task. The selected clones should display high performance in a series of yield- and quality-related traits. Selection indices can provide information about which clones can best combine the traits of agronomic interest. In this study, different selection indices were evaluated in a population of 220 clones. The following traits were evaluated: weight of 10 stalks with straw, weight of 10 stalks with no straw, tons of cane per hectare with straw, tons of cane per hectare with no straw, sucrose content, fiber percentage, and tons of fiber per hectare. The selection indices of Smith (1936) and Hazel (1943) and Mulamba and Mock (1978), the base index (Williams, 1962), and the index of Pesek and Baker (1969) were used. The selection index of Mulamba and Mock (1978) without economic weight estimates, the index of Mulamba and Mock with economic weights based on heritability, and the index of Pesek and Baker (1969) with the desired gains based on genetic standard deviations were efficient for the selection of energy cane clones with good fiber yield, sucrose content, and tons of cane per hectare.

Selection in sugarcane based on inbreeding depression.

This study aimed to evaluate the gene action associated with yield-related traits, including mean stalk weight (MSW), tons of sugarcane per hectare (TCH), and fiber content (FIB) in sugarcane. Moreover, the viability of individual reciprocal recurrent selection (RRSI-S1) was verified, and the effect of inbreeding depression on progenies was checked. The results were also used to select promising genotypes in S1 progenies. Eight clones (RB925345, RB867515, RB739359, SP80-1816, RB928064, RB865230, RB855536, and RB943365) and their respective progenies, derived from selfing (S1), were evaluated. Several traits, including the number of stalks, MSW, soluble solids content determined in the field, stalk height, stalk diameter, TCH, soluble solids content determined in the laboratory, sucrose content, and FIB were evaluated in a randomized block design with hierarchical classification. The results showed that the traits with predominant gene action associated with the dominance variance of MSW and TCH were most affected by inbreeding depression. The FIB, with predominant additive control, was not affected by selfing of the clones, and the RB867515⊗, RB928064⊗, RB739359⊗ and RB925345⊗ progenies performed best. Therefore, the use of S1 progenies for RRSI-S1 in sugarcane breeding programs is promising, and it should be explored for the future breeding of clones with high FIB levels.

Genetic diversity and coefficient of parentage between clones and sugarcane varieties in Brazil.

The success of the development of new sugarcane varieties is associated with the ability to correctly select the genitor. The aim of this study was to evaluate the genetic diversity between 113 clones and sugarcane varieties using the Ward-modified location model procedure with added information about the coefficient of parentage and endogamy. In this study, data was used from 100 experiments that evaluated clones; the experimental phase was conducted in 70 places between the years 2002 and 2009 on the outlining in random blocks. According to the diversity analysis, 3 groups formed: G1, G2, and G3, which were composed of 58, 8, and 47 genotypes, respectively. The clones of groups G1 and G3 were the most outstanding. Thus, biparental crossbreeding involving clones and varieties of these 2 groups can efficiently obtain transgressive genotypes. Knowledge of the heterotypic groups indicated by the Ward-modified location model method, along with the parentage information, will make it a lot easier to define the desirable and undesirable crossbreeds for public and private breeding programs that develop sugarcane varieties.

Genetically modified crops: Brazilian law and overview.

In Brazil, the first genetically modified (GM) crop was released in 1998, and it is estimated that 84, 78, and 50% of crop areas containing soybean, corn, and cotton, respectively, were transgenic in 2012. This intense and rapid adoption rate confirms that the choice to use technology has been the main factor in developing national agriculture. Thus, this review focuses on understanding these dynamics in the context of farmers, trade relations, and legislation. To accomplish this goal, a survey was conducted using the database of the National Cultivar Registry and the National Service for Plant Variety Protection of the Ministry of Agriculture, Livestock and Supply [Ministério da Agricultura, Pecuária e Abastecimento (MAPA)] between 1998 and October 13, 2013. To date, 36 events have been released: five for soybeans, 18 for corn, 12 for cotton, and one for beans. From these events, 1395 cultivars have been developed and registered: 582 for soybean, 783 for corn and 30 for cotton. Monsanto owns 73.05% of the technologies used to develop these cultivars, while the Dow AgroScience - DuPont partnership and Syngenta have 16.34 and 4.37% ownership, respectively. Thus, the provision of transgenic seeds by these companies is an oligopoly supported by legislation. Moreover, there has been a rapid replacement of conventional crops by GM crops, whose technologies belong almost exclusively to four multinational companies, with the major ownership by Monsanto. These results reflect a warning to the government of the increased dependence on multinational corporations for key agricultural commodities.

Genetic diversity in sugarcane varieties in Brazil based on the Ward-Modified Location Model clustering strategy.

We evaluated the genetic diversity of 77 clones of sugarcane used in crosses made by the Brazilian interuniversity network for the development of the sugar/energy sector (RIDESA) breeding program. Characterization of the genotypes was carried out at the ratoon stage, based on eight morphological traits and seven agronomic traits. Diversity analysis was carried out beginning with the Ward-Modified Location Model. The ideal number of groups was three. Groups 1, 2, and 3 were composed of 37, 21, and 19 accessions, respectively. Group 1 was formed entirely of commercial varieties (hybrids of advanced generations) and elite clones, with the exception of the old varieties 'Caiana Fita' and 'Cana Blanca' (hybrids of Saccharum officinarum). In general, group 2 had more divergent accessions regarding origin, including L60-14, NG57-6, TUC77-42, IN84-105 (hybrid of S. officinarum), and 28NG289 (species of S. robustum). Group 3 was formed entirely of commercial varieties and elite clones from the RIDESA program, with the exception of genotypes Co285 (India), Q124 (Australia) and VAT90-212 (unknown origin). The analysis based on the Ward-Modified Location Model procedure resulted in an adequate and clearly discriminating grouping of sugarcane accessions, allowing the use of all the available information about the genotypes, in a mix of continuous and categorical variables.

Genetic diversity and selection gain in the physic nut (Jatropha curcas).

The use of efficient breeding methods depends on knowledge of genetic control of traits to be improved. We estimated genetic parameters, selection gain, and genetic diversity in physic nut half-sib families, in order to provide information for breeding programs of this important biofuel species. The progeny test included 20 half-sib families in 4 blocks and 10 plants per plot. The mean progeny heritability values were: 50% for number of bunches, 47% for number of fruits, 35% for number of seeds, 6% for stem diameter, 26% for number of primary branches, 14% for number of secondary branches, 66% for plant height, and 25% for survival of the plants, demonstrating good potential for early selection in plant height, number of branches, and number of fruits per plant. In the analysis of genetic diversity, genotypes were divided into 4 groups. Genotypes 18, 19, 20, and 8 clustered together and presented the highest means for the vegetative and production. Lower means were observed in the 17, 12, 13, and 9 genotypes from the same group. We detected genetic variability in this population, with high heritability estimates and accuracy, demonstrating the possibility of obtaining genetic gains for vegetative characters and production at 24 months after planting.

Parâmetros genéticos de frutos, sementes e plântulas de Jatropha ribifolia (Pohl) Baill. (Euphorbiaceae) / Genetic parameters of fruits, seeds and seedlings of Jatropha ribifolia (Pohl) Baill. (Euphorbiaceae)

O objetivo deste trabalho foi estimar parâmetros genéticos de frutos, sementes e plântulas de Jatropha ribifolia (Pohl) Baill., subsidiando futuros programas de melhoramento e conservação genética. Foram selecionadas 20 matrizes da espécie e os frutos coletados em área de Caatinga, no Município de Jequié - BA / Brasil. Para descrição morfológica foram observadas características de 50 frutos e 50 sementes. Para germinação foi utilizado o delineamento experimental inteiramente casualizado com 20 tratamentos (progênie) e três repetições de 20 sementes. O fruto de J. ribifolia é seco, cápsula loculicida e septicida, endocarpo lenhoso e deiscência explosiva (autocórica). A semente é oval, endospérmica, de testa lisa, com diferentes colorações e carúncula presa na parte ventral. O hilo é visível e a rafe bem marcada longitudinalmente. A germinação é hipógea-criptocotiledonar. O tempo médio para germinação foi de 10 a 40 dias. As matrizes de J. ribifolia estudadas apresentaram variabilidade genética significativa para a maioria dos caracteres estudados.

The aim of this study was to estimate genetic parameters of fruits, seeds and seedlings of Jatropha ribifolia (Pohl) Baill, subsidizing future breeding and genetic conservation programs. Twenty matrices of the species and the fruits collected in the Caatinga area in the city of Jequié - BA / Brazil were selected. For morphological description, the features of 50 fruits and 50 seeds were observed. For germination, completely randomized design was used with 20 treatments (progeny) and three replicates of 20 seeds. J. ribifolia fruit is dry and has loculicidal and septicidal capsule, woody endocarp and explosive dehiscence (autochory). The seed is oval, endospermic and has smooth testa and different colors, with caruncle attached to the ventral part. The hilum is visible and the raphe is longitudinally marked. Germination is hypogeal-cryptocotylar. The average time for germination was from 10 to 40 days. The matrices of J. ribifolia showed significant genetic variability for most of the studied traits.