Genetic Variability among Genotypes of Physic Nut Regarding Seed Biometry

With probable center of origin in Brazil, the species Jatropha curcas L., known as physic nut, is a tropical oilseed with potential for cultivation aiming at the production of biodiesel. This study was conducted with the objective of investigating the genetic variability regarding the morphology of seeds of physic nut, using biometric analyses to identify variables that have potential for the study of the diversity of the species and the classification of genotypes. Seeds of 22 genotypes of physic nut, from the germplasm bank of Embrapa Agroenergia (Brazil) were evaluated regarding characteristics of size and mass. The genotypes of Jatropha curcas L. selected by the Brazilian breeding program presented high diversity for characteristics of the seeds, allowing the exploration of this genetic variability to classify genotypes in different groups. In addition, variables related to the biomass of the seeds present high relative contributions to the diversity observed in the genotypes.

Severity of Leaf Rust and Brown Eyespot in Genotypes of Coffea arabica L.Cultivated with High Plant Density

This study investigated the severity of leaf rust and brown eyespot in genotypes of Coffea arabica L. cultivated with high plant density in the region of Caparaó-ES. The experiment was conducted in a competition field, cultivated with high plant density (8333 plants per hectare), following a randomized block design, with 16 genotypes and four replications. The plants were evaluated during consecutive harvests to study two complete reproductive cycles (from 2010 to 2012). Data were obtained for the phenologicalstages of flowering, graining, maturation and vegetative rest of each cycle. The severity of leaf rust (Hemileia vastratrix) and brown eyespot (Cercospora coffeicola) was evaluated using descriptive scales. It was observed that the genotypes are able to keep a considerable level of resistance to the leaf rust and brown eyespot when cultivated with increased density. The genotypes presented variability regarding the severity of the leaf rust and brown eyespot, indicating the existence of differential levels of resistance between them. For cultivation with high plant density, the genotypes Katipó, Paraíso MG H419-1, H419-3-3-7-16-4-1-1, Araponga MG1, Catucaí Amarelo 24/137, Catiguá MG2, Sacramento MG1, Pau-Brasil MG1, Catiguá MG3, Oeiras MG 6851 and Tupi present higher level of resistance for leaf rust. In addition, the genotypes Paraíso MG H419-1, Catiguá MG2, Pau-Brasil MG1, Catiguá MG3, Oeiras MG 6851, Tupi, Catuaí IAC 44, Catuaí IAC 81 and Catuaí IAC 144 present higher level of resistance for brown eyespot.

Differential Growth of Genotypes of Physic Nut Conditioned by Nitrogen Fertilization

The adequate supply of nitrogen is essential for the plant metabolism. This nutrient has an irreplaceable role on the vegetative and reproductive growth of physic nut;therefore the correct management of the fertilization is very important, particularly in tropical regions, which present considerable losses of nitrogen by leaching and volatilization processes. This study was made with the objective of evaluating the growth of genotypes of physic nut conditioned by nitrogen fertilization. The experiment was conducted in controlled environment, following a factorial scheme 12 × 4, with 12 Brazilian genotypes of Jatropha curcas L. and 4 levels of nitrogen fertilization (0%, 50%, 100% and 150% of the recommendation), in completely randomized design, with four replications. The growth of the genotypes was evaluated at 100 days of cultivation. Positive response to the increase in the nitrogen supply was observed in most genotypes, with gain in plant height, stem diameter, number of leaves, leaf area and root volume. The levels of nitrogen fertilization promoted differential growth between genotypes, being possible to identify genotypes with superior growth for each level.

Adaptation to Long-Term Rainfall Variability for Robusta Coffee Cultivation in Brazilian Southeast

Coffee is one of the world most traded agricultural commodities. Currently, a lot of attention has been on Robusta coffee (Coffea canephora Pierre ex A. Froehner) because it seems to evidence a greater tolerance to extreme climatic events than Arabica coffee (C. arabica L.). Despite this, only a few works have been developed aimed at discriminating the climatic vulnerability in regions which prioritize robust coffee production. The aim of this work was to analyze historical climatic variables in space and time for the characterization of climatic vulnerability of micro-regions, in search of mitigation and adaptation, which might support the improvement of production systems of C. canephora coffee trees. The case study was carried out for one of the largest production regions of Robusta coffee of the world, in Brazil, geographically located between the 39°38' and 41°50' West longitude meridians and the 17°52' and 21°19' South latitude parallels. The vulnerability was characterized by the spatial and temporal variation of rainfall and rainfall seasonal pattern (based on 30 years of historical data), elements of climatic water balance, elevation and area planted with Robusta coffee. The choice of mitigation and adaptation were based on widely validated criteria. Overall, the results show that the vulnerability of Robusta coffee is related to low index of rainfall, the rainfall seasonability and the water deficiency. In the studied region, there is approximately 42% of some type of water vulnerability during the year, with a severe to medium scale;this vulnerability is very pronounced in regions farther away from the coast of the Atlantic Ocean, since for a year approximately 92% of them are water deficient. In addition, the data show that this distance from the ocean implies a reduction of 75% in the phases of water surplus not only. The strategies of greater potential for adaptation and mitigation are related to the planting of improved genotypes, utilization of polycultures systems, increasing plant density, the implementation of irrigation systems and the management of spontaneous plants.

Applicability of the Method of Linear Dimensions to Estimate Leaf Area in Improved Genotypes of Coffea arabica and Coffea canephora

There are different methods to determinate leaf area in coffee plants;however, methodologies that allow measurement of leaf area accurately and in nondestructive ways are very important, as they are less economically costly and enable measurements on the same leaf over time, making it possible to describe accurate patterns of growth. The objective of this study was to investigate the applicability of the method to estimate leaf area using linear dimensions of leaves for improved genotypes of Coffea arabica L. and Coffea canephora Pierre ex A. Froehner. The experiment was conducted in two separated competition fields, each one following factorial schemes 10 × 2, with 10 genotypes and 2 methods to obtain the leaf area: measuring linear dimensions, and using equation model (estimated leaf area) and leaf area integrator (real leaf area). The genotypes for both Coffea arabica L. and Coffea canephora Pierre ex A. Froehner have different leaf areas, making it possible to discriminate groups of genotypes for both species using the size of their leaves as classification criteria. Even with the differences between genotypes, the pattern of leaf shape remains similar, confirming the applicability of the method to estimate leaf area using linear dimensions of leaves for improved genotypes, such as the model proposed by Barros, without the occurrence of loss of accuracy for the improved genotypes, for both Arabica and Conilon coffee, studied in this experiment.

Growth and Quality of Clonal Plantlets of Conilon Coffee(Coffea canephora Pierre ex A.Froehner)Influenced by Types of Cuttings

To achieve high crop yieldin agriculture, the production of plantlets of superior quality is one of thebasic prerequisites. For conilon coffee, the current recommendation in theproduction of clonal plantlets through vegetative propagation is to usediagonal cuttings, in bevel form. However, there are indications that othertypes of cutting have been successfully used to produce plantlets. In thiscontext, this experiment was conducted with the objective of studying thedevelopment of plantlets of conilon coffee obtained by different types ofcuttings. The experiment was conducted in a greenhouse. The cuttings wereobtained from the middle portion of orthotropic stems of standardized plants.The experiment followed a split plot in time design, with three types ofcuttings (bevel, sharp bevel and straight) and two times of evaluation, withfour repetitions. At 30 and 120 days after planting, plantlets were collectedand evaluated. The results show the increase occurred in the variables due tothe straight cut when compared to the others, except for stem diameter.Emphasizing in this context, the straight cut promoted an increase in seedlingheight, production of biomass and in the Dickson’s quality index when comparedto cuttings in bevel and sharp bevel.