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Goiânia, Brazil

Severino L.S.,Embrapa Algodao | Auld D.L.,Texas Tech University
Australian Journal of Crop Science | Year: 2014

Castor (Ricinus communis L.) is an industrial oilseed crop that is tropical by origin but cultivated in temperate regions. There are reports that castor seed yield is significantly reduced by exposure to cool temperatures during the seed filling stage. The aim of this study was to measure the effect of the air temperature on the growth rate of castor seed and to determine the base temperature for this critical physiological process. Racemes of castor cv. Brigham initiated at different days were tagged after pollination, and fruits were harvested in five days increments during the 2012 growing season at Lubbock, TX, USA (latitude 33°36' N).The air temperature was recorded at 5-minutes intervals from tagging the first raceme until the end of the growing season. The seed water content and seed dry weight were used for the calculation of the influence of air temperature in the seed growth rate and to determine the base temperature of this physiological process. It was found that the seed growth rate was reduced as the air temperature became cooler. The seed growth rate was 13.8 mg day-1 in the racemes initiated on 31 July (28 °C, on average), compared with 4.3 mg day-1 in the racemes initiated on 20 August (20 °C, on average). The base temperature (used for calculation of degree-days) for castor seed growth was estimated to be 15 °C, and a castor seed required 464 degree-days to reach physiological maturity. Source

The cotton mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) has been reported occurring in several countries causing severe losses in economically important crops, including cotton. Based on information reported by farmers in the regions of the Southwest and Middle São Francisco, Bahia and also in the regions of the Agreste and Semi-arid of the Paraiba State, high infestations of cotton mealybugs have occurred in these regions during the cotton season of 2007 and 2008. The cotton mealybug was identified as P. solenopsis and this represents the first record of this insect attacking cotton in Brazil. Source

Teixeira A.D.D.,Federal University of Vicosa | Fialho M.D.C.Q.,Federal University of Vicosa | Zanuncio J.C.,Federal University of Vicosa | Ramalho F.D.S.,Embrapa Algodao | Serrao J.E.,Federal University of Vicosa
Arthropod Structure and Development | Year: 2013

Cell death, proliferation, and differentiation in some developmental stages of insects have been studied in the midgut of ametabolous, which undergo only continuous growth, and holometabolous, which undergo complete metamorphosis. However, in hemimetabolous insects, evolutionarily intermediate between ametabolous and holometabolous, midgut reorganization during the post-embryonic development has been poorly studied. The present study evaluates the post-embryonic development of the midgut of a hemimetabolous insect, Podisus nigrispinus, to test the hypothesis that these insects have programmed cell death and proliferation followed by differentiation of regenerative cells during midgut growth from nymphs to adult. The morphometrical data showed a 6-fold increase in midgut length from the first instar nymph to the adult, which did not result from an increase in the size of the midgut cells, suggesting that the growth of the midgut occurs by an increase in cell number. Cell death was rarely found in the midgut, whereas proliferation of regenerative cells occurred quite frequently. The growth of the midgut of P. nigrispinus appears to result from the proliferation of regenerative cells present in the epithelium; unlike ametabolous and holometabolous insects, the midgut of P. nigrispinus does not undergo extensive remodeling, as shown by the low frequency of digestive cell death. © 2013 Elsevier Ltd. Source

Severino L.S.,Embrapa Algodao | Auld D.L.,Texas Tech University
Industrial Crops and Products | Year: 2013

A deeper understanding of the growth and development of castor plant (Ricinus communis L.) will be required for the transition from the low input/low yield present scenario to the desired condition of mechanically harvested with high seed yield. The objective of this review was to discuss important aspects of castor growth and development in order to propose a framework for the study of aspects that can potentially impact castor breeding and crop management. Gaps in the knowledge were emphasized. Castor has a slow and cold-sensitive germination that negatively impact crop establishment. The importance of cotyledonary leaves has been poorly studied. Leaf area is very responsive to growing conditions, and factors that influence leaf size and leaf number were discussed. Leaves play a role beyond photosynthesis, particularly on the storage of nutrients and assimilates. Remobilization of stored compounds during leaf senescence is pivotal for seed filling, and this process can impact seed yield in early maturing varieties. Studies on castor root are scarce, despite its importance for plant growth. Some physiological processes of seed development such as seed filling duration and seed growth rate play an important role in the adaptation to different environments and for increasing earliness. Seed abortion is an important mechanism of sink adjustment to environmental conditions which can be explored for increased plasticity. Harvest index is a simple approach that historically has been very useful for increasing seed yield of many crops, and that should be used more often in castor research. Finally, modeling would be an obvious consequence of progresses in the understanding of physiological processes controlling castor plant growth and development. © 2013 Elsevier B.V. Source

Soares D.J.,Embrapa Algodao
Australasian Plant Disease Notes | Year: 2010

A powdery mildew fungus belonging to the genus Oidium subgen. Fibroidium was found on Heliotropium indicum in north-east Brazil. This fungus was identified as Oidium heliotropii-indici and is described for the first time on this host from Brazil. © Australasian Plant thology ociety 2010. Source

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