Yacon production at different planting seasons and growing environments / Produção de yacon em diferentes estações de plantio e ambientes de cultivo

Yacon is a functional food with great potential for horticultural exploitation and its cultivation demands the generation of agronomic information. To address these needs, this study was performed to evaluate the production of yacon planted in different planting seasons under two growing conditions in Brazil. The experiments were conducted in two different locations, one in the mountain region (tropical microclimate at altitude with milder temperatures) and the other in the lowland region (warm tropical microclimate with higher temperatures). At both sites, yacon was planted in four seasons: autumn (April), winter (July), spring (September) and summer (December). At harvest, the tuberous roots were evaluated for leaf area index and the variables of vegetative development and productivity of plants (for total and standard commercial roots). It was concluded that yacon cultivation in mountain conditions (tropical climate with milder temperature) promotes the development and production of yacon. Additionally, planting in the autumn for both growing conditions (mountain or lowland) promotes the development and production of yacon, including increased production of roots of better commercial grade, allowing greater economic profitability. These results indicate that temperature has an influence on the growth and yield of the tuberous roots of yacon, and milder temperatures were more favourable.

A yacon é um alimento funcional com grande potencial para exploração hortícola e seu cultivo exige a geração de informações agronômicas. Para atender a essas necessidades, este estudo foirealizado com o objetivo de avaliar a produção de yacon plantada em diferentes estações de plantio sob duas condições de crescimento no Brasil. Os experimentos foram conduzidos em dois locais diferentes, um em região montanhosa (microclima tropical de altitude com temperaturas mais amenas) e o outro em região de baixada (microclima tropical quente com temperaturas mais elevadas). Em ambos os locais, a yacon foi plantada em quatro estações: outono (abril), inverno (julho), primavera (setembro) e verão (dezembro). Por ocasião da colheita das raízes tuberosas foram avaliados o índice de área foliar e variáveis de desenvolvimento vegetativo e produtividade das plantas (raízes tuberosas totais e por padrão). Concluiu-se que o cultivo de yacon em condições de montanha (clima tropical com temperatura mais suave) promove melhor desenvolvimento e produção de yacon. Além disso, plantar no outono para ambas as condições de crescimento (montanha ou baixada) promove melhor desenvolvimento e produção de yacon, incluindo o aumento da produção de raízes tuberosas de melhor qualidade comercial, permitindo maior rentabilidade econômica. Estes resultados indicam que a temperatura influenciou o crescimento e o rendimento das raízes tuberosas de yacon e as temperaturas mais amenas foram mais favoráveis.

Effects of shading on tuberous root traits, photosynthetic characteristics and gene transcription of Rehmannia glutinosa / 中草药

To reveal the effects of shading on tuberous root and photosynthetic characteristics of Rehmannia glutinosa, and analyze the molecular mechanism of shading affecting the expansion of R. glutinosa tuberous root by transcriptome sequencing. Methods: R. glutinosa plants were treated with full light, 60% shading and 90% shading. High-throughput sequencing was used to sequence the transcriptome of the R. glutinosa tuberous roots treated with full-light and 90% shading, and the differentially expressed genes were screened out. The expression characteristics of some genes in tuberous roots and leaves were analyzed by real-time fluorescence quantitative PCR. Results: After shading, the number of parenchyma cell layers in the tuberous roots was decreased, but the proportion of ducts was increased, the length, diameter and fresh weight of tuberous roots were decreased significantly, and the tuberous roots barely expanded under 90% shading treatment. The number of parenchyma cell was decreased and the proportion of duct was increased in root tubers of R. glutinosa. With the increase of shading degree, the content of chlorophyll a and b and total chlorophyll content were gradually decreased, and photosynthetic capacity was decreased. A total of 3 348 differentially expressed genes were obtained by transcriptome analysis, of which 1 396 were down-regulated and 1 952 were up-regulated. Through enrichment analysis of KEGG metabolic pathway, 1 668 differentially expressed genes (53.4%) were enriched into 117 metabolic pathways, and 17 of them were significantly enriched pathways. The plant hormone signaling pathway was enriched firstly, followed by the plant pathogen interaction pathway, the phenylethanoid glycoside biosynthesis pathway, starch and sucrose metabolic pathways were also enriched significantly. In the hormone signaling pathway, most of different expressed genes were up-regulated. Eleven expansin genes were down-regulated under 90% shading, only five expansin genes were up-regulated. Two of beta-amylase genes (Bmy) related to starch degradation were up-regulated when shading treated, while the sucrose phosphate synthase genes (SPS) were down-regulated. Most of the genes involved in lignin synthesis were down-regulated and most of the genes involved in cellulose synthesis were up-regulated. Conclusion: The photosynthetic capacity of R. glutinosa was decreased under shading conditions, and led to the accumulation of photosynthate decreased in its leaf and tuberous root. R. glutinosa plant responded to shading by regulating the differential expression of a series of hormone pathway genes, which prevent the expansion of tuberous roots.

Tending of wild Heterosmilax yunnanensis / 中国中药杂志

To minimize the predatory harvest of Heterosmilax yunnanensis and maintain the sustainable utilization of its resources, a study on the tending technology of wild H. yunnanensis was carried out. The results showed that the tuber tending model had a higher seed emergence rate, shorter growth period and easier control of male and female ratios than other tending models; by removing shrubs, topping, bending pruning, controlling insects and pests and other effective technical measures, the growth period of H. yunnanensis was shortened; the average annual net income of the tending area was 1 086 yuan/mu (1 mu≈666.67 m²), which was 86.9% higher than before. This study was conducive to increasing the yield and quality of H. yunnanensis in Karst landform area, and instructive for the tending of other wild traditional Chinese medicinal herbs in this area.

Intervalos entre podas de duas variedades de mandioca / Intervals between prunings of two cassava varieties

Este experimento foi conduzido com o objetivo de avaliar o efeito do intervalo entre podas em duas variedades de mandioca. O ensaio foi instalado na área experimental da Universidade Estadual do Sudoeste da Bahia, Campus de Vitória da Conquista, no período de dezembro de 2008 a julho de 2010, utilizando-se o delineamento em blocos ao acaso, com dez tratamentos e três repetições. Os tratamentos foram arranjados segundo esquema fatorial 2x5, formados pela combinação entre duas variedades de mandioca (Caitité e Sergipe) e cinco intervalos entre podas (dois, quatro, seis e oito meses após o plantio e testemunha - sem poda). A poda da parte aérea foi realizada à altura de 15 cm em relação à superfície do solo. Foram avaliadas as seguintes características: produtividades de parte aérea, raiz e amido; porcentagem de massa seca e de amido e rendimento de farinha. As médias de variedades foram comparadas pelo teste Tukey e, para os intervalos entre podas, foi realizada análise de regressão. Foram utilizados contrastes para a comparação da testemunha com a média dos tratamentos podados. A variedade Caitité apresentou maior produtividade de raízes e maior produtividade de amido, compensando a redução no teor de massa seca de raízes que ocorreu com a poda. A poda influenciou negativamente a maioria das características avaliadas, entretanto, se realizada em intervalos a cada seis a oito meses, permite melhor distribuição da produção de parte aérea, sem promover elevada redução na produtividade de raízes tuberosas.

This experiment was conducted to evaluate the effect of pruning interval in two cassava varieties. The experiment was installed in the experimental area of Universidade Estadual do Sudoeste da Bahia, campus of Vitória da Conquista - BA, from December 2008 to July 2010, using a randomized complete block design, with ten treatments and three replications. Treatments were arranged in a 2x5 factorial design, formed by combining two varieties of cassava (Caitité and Sergipe) and five pruning intervals (two, four, six and eight months after planting and a witness - no pruning). The pruning was held at a height of 15 cm from the soil surface. Were evaluated the following characteristics: yields of shoot, root and starch; dry matter content, starch and flour yield. The average varieties were compared by Tukey test and for intervals between pruning, regression analysis. The variety Caitité had higher root yield and higher productivity starch, offsetting the reduction in the dry mass of roots that occurred with the pruning. Pruning negatively influenced most valued characteristics, however, was performed at intervals of every six to eight months, allows better distribution of production shoots, without promoting high reduction in root yield.

Anatomy of the underground system in Vernonia grandiflora Less. and V. brevifolia Less. (Asteraceae)

This work dealt with the anatomy of the underground system in Vernonia grandiflora Less. and V. brevifolia Less. (Vernonieae; Asteraceae), two perennial geophytes, to elucidate their ability to sprout in the Brazilian Cerrado conditions. V. grandiflora, a subshrubby species, possessed a thickened underground system constituted by a xylopodium and many tuberous roots. The xylopodium had stem and root structure and its buds were axillary or originated from the cortical parenchyma proliferation. The tuberous roots produced by this organ were adventitious and accumulated inulin-type fructans mainly in the cortical parenchyma. The thickened underground system of V. brevifolia, an herbaceous species, was a tuberous primary root whose buds originated from the proliferated pericycle. The occurrence of these bud-forming underground systems, which stored reserve compounds, enabled these plants to survive throughout unfavourable environmental conditions in the Cerrado, such as dry season and frequent fires in the winter.

Este trabalho teve como objetivo estudar a anatomia dos sistemas subterrâneos de Vernonia grandiflora Less. e V. brevifolia Less. (Vernonieae; Asteraceae), duas geófitas perenes, a fim de esclarecer sua capacidade para brotar em condições de Cerrado. O sistema subterrâneo espessado de V. grandiflora, uma espécie subarbustiva, é constituído pelo xilopódio e por várias raízes tuberosas. O xilopódio possui estrutura mista (radicular e caulinar) e suas gemas são de origem axilar ou se originam a partir da proliferação do parênquima cortical. As raízes tuberosas produzidas por este órgão são adventícias e acumulam frutanos do tipo inulina, principalmente no parênquima cortical. Em V. brevifolia, uma espécie herbácea, o sistema subterrâneo espessado é constituído pela raiz primária cujas gemas são originadas a partir do periciclo proliferado. A ocorrência destes sistemas subterrâneos gemíferos, que armazenam compostos de reserva, permite que estas plantas sobrevivam às condições desfavoráveis do Cerrado, tais como a estação seca e os freqüentes incêndios durante o inverno.