Vigor vegetativo de café conilon e seu potencial para indução de calos in vitro

Considering the importance of the culture of Coffea canephora in the Brazilian Amazon and the need for genetic improvement of this species for cultivation in the state of Rondonia, he objective of this study was to evaluate the correlation between the initial vigor of clonal plants of C. canephora variety Conilon, under field conditions, and its potential for in vitro propagation. Promising clones belonging to the Genetic Improvement Program of Coffea sp were used Embrapa (Brazilian Agricultural Research Corporation) Rondonia. The plant height, number and length of orthotropic shoots in coffee at 10 months after planting were evaluated. In the laboratory, leaves of plants of each clone were segmented into fragments of 1 cm ² which were inoculated on MS medium containing half the concentration of salts, AIB (10 μM), 2,4-D (20 μM) and 2iP (10 μM), sugar (20 g cm-3) and agar (6 g cm-3). Cultures were maintained in a growth chamber under 16 h photoperiod at 2000 lux and 24 ± 2 º C. The callus induction and the percentage of leaf area covered with callus cells were observed within 90 days. Clone 9 showed greater vegetative growth in the field. Only clone 12 showed no callus induced, all other clones were highly responsive to callus induction, and clone 5 showed a higher percentage of leaf area covered with callus cells. There was no phenotypic correlation between early vigor in the field and calogênico potential in vitro, for clones of coffee used.Considerando a relevância da cultura de Coffea canephora para a Amazônia brasileira e a necessidade de melhoramento genético dessa espécie para cultivo no estado de Rondônia, objetivou-se, neste trabalho, avaliar a correlação existente entre o vigor vegetativo inicial de plantas clonais de C. canephora var. Conilon, em condições de campo, e seu potencial para propagação in vitro. Foram utilizados clones promissores pertencentes ao Programa de Melhoramento Genético de Coffea sp. da Embrapa Rondônia. Foram avaliadas as características altura da planta, número e comprimento de brotos ortotrópicos, em cafeeiros com 10 meses pós-plantio. Em laboratório, folhas de plantas de cada clone foram segmentadas em fragmentos de 1 cm² os quais foram inoculados em meio MS, contendo metade da concentração dos sais, AIB (10 μM), 2,4-D (20 μM) e 2iP (10 μM), açúcar (20 g cm-3) e ágar (6 g cm-3). As culturas foram mantidas em sala de crescimento, sob fotoperíodo de 16 horas a 2000 lux e 24±2ºC. A indução de calos e a porcentagem de área foliar coberta com células de calo foram observadas nos 90 dias subsequentes. O clone 9 demonstrou maior crescimento vegetativo em campo. Apenas o clone 12 não apresentou calos induzidos, todos os outros clones foram altamente responsivos à indução de calos, e o clone 5 apresentou maior porcentagem de área foliar coberta com células de calo. Não houve correlação fenotípica entre vigor vegetativo inicial em campo e potencial calogênico in vitro, para os clones de cafeeiro utilizados

Quality evaluation of Coffea canephora ‘Apoatã’ seeds for rootstock production

Coffea canephora ‘Apoatã’ seeds are used for the formation of rootstocks for grafting of C. arabica seedlings. The quality of seeds and the individualization of used genotypes are prevalent factors for the formation of vigorous rootstocks that will enhance the formation of quality seedlings. The aim of the present study was to characterize and evaluate the seed quality of C. canephora ‘Apoatã’ genotypes for potential use of rootstocks for C. arabica species. Were used seeds of 30 C. canephora ‘Apoatã’ genotypes, obtained from the experimental field of Embrapa Rondônia in Ouro Preto do Oeste, RO, Brazil. The seeds were processed and subjected to germination, first germination count and tetrazolium tests. Moisture, 100- seed mass and chemical composition analyses of seeds were also determined. The mass, physiological quality and chemical composition of C. canephora ‘Apoatã’ seeds vary according to the genotype. The variation of the physiological quality of C. canephora ‘Apoatã’ seeds is not related individually to caffeine, total sugars, ash, ether extract, crude fiber protein and chlorogenic acid. Seed batches of C. canephora ‘Apoatã’ from different genotypes contain seeds of different sizes, being indicated the classification before the processing stage in order to prevent mechanical damages

Growth retardants in wheat and its effect in physiological quality of seeds

Plant lodging in wheat has been controlled through growth retardants. However, there is lack of information on the effect of these products on the physiological quality of seeds. The objective of this study was to evaluate the physiological quality of wheat seeds obtained under different rates and application times of three growth retardants. The trial was carried out in Viçosa-MG, from May to September 2005, in a factorial and hierarchical scheme, in randomized block design with four replications and a control treatment. The treatments consisted of 500, 1000 and 1500g ha-1 of chlormequat; 40, 80 and 120g ha-1 of paclobutrazol and 62.5, 125 and 187.5g ha-1 of trinexapac-ethyl applied at the 6 or 8 growth stage based on the scale of Feeks and Large, and a control treatment without growth retardant application. Leaf application of growth retardants as chlormequat, paclobutrazol and trinexapac-ethyl did not affect the germination and vigor of wheat seeds.O acamamento de plantas na cultura do trigo tem sido controlado com o uso de redutores de crescimento. No entanto, há carência de informações sobre o efeito desses produtos na qualidade fisiológica de sementes. O objetivo deste estudo foi avaliar a qualidade fisiológica das sementes de trigo obtidas sob efeito de doses e épocas de aplicação de três redutores de crescimento. O experimento, conduzido em Viçosa, Minas Gerais, entre maio e setembro de 2005, foi instalado com tratamentos em esquema fatorial e hierárquico com uma testemunha, no delineamento em blocos casualizados, com quatro repetições. Os tratamentos foram 500, 1000 e 1500g ha -1 de clormequat; 40, 80 e 120g ha -1 de paclobutrazol e 62,5, 125 e 187,5g ha -1 de trinexapac-etil aplicados no estádio 6 ou 8 da escala Feeks e Large, mais uma testemunha sem aplicação de redutor. A aplicação foliar dos redutores de crescimento clormequat, paclobutrazol e trinexapac-etil não afeta a germinação e o vigor das sementes de trigo

A bitter future for coffee production? Physiological traits associated with yield reveal high vulnerability to hydraulic failure in Coffea canephora

International audienceAbstract The increase in frequency and intensity of drought events have hampered coffee production in the already threatened Amazon region, yet little is known about key aspects underlying the variability in yield potential across genotypes, nor to what extent higher productivity is linked to reduced drought tolerance. Here we explored how variations in morphoanatomical and physiological leaf traits can explain differences in yield and vulnerability to embolism in 11 Coffea canephora genotypes cultivated in the Western Amazon. The remarkable variation in coffee yield across genotypes was tightly related to differences in their carbon assimilation and water transport capacities, revealing a diffusive limitation to photosynthesis linked by hydraulic constraints. Although a clear trade‐off between water transport efficiency and safety was not detected, all the studied genotypes operated in a narrow and/or negative hydraulic safety margin, suggesting a high vulnerability to leaf hydraulic failure (HF), especially on the most productive genotypes. Modelling exercises revealed that variations in HF across genotypes were mainly associated with differences in leaf water vapour leakage when stomata are closed, reflecting contrasting growth strategies. Overall, our results provide a new perspective on the challenges of sustaining coffee production in the Amazon region under a drier and warmer climate