Young Banana Plants Research Articles

PM 7/21 (2) Ralstonia solanacearum, R. pseudosolanacearum and R. syzygii (Ralstonia solanacearum species complex)

Specific scopeThis Standard describes a diagnostic protocol for Ralstonia solanacearum, Ralstonia pseudosolanacearum and Ralstonia syzygii, i.e. phylotype/sequevar strain in the Ralstonia solanacearum Species Complex (RSSC).It should be used in conjunction with PM 7/76 Use of EPPO diagnostic protocols.Specific approval and amendmentApproved in 2003‐09. First revised in 2018‐02.

Chrysodeixis chalcites nucleopolyhedrovirus (ChchNPV): Natural occurrence and efficacy as a biological insecticide on young banana plants in greenhouse and open-field conditions on the Canary Islands.

Chrysodeixis chalcites, an important pest of banana crops on the Canary Islands, is usually controlled by chemical insecticides. The present study aimed to evaluate the efficacy of the most prevalent isolate of the Chrysodeixis chalcites nucleopolyhedrovirus (ChchNPV, Baculoviridae) as a biological insecticide. Overall the prevalence of ChchNPV infection in C. chalcites populations was 2.3% (103 infected larvae out of 4,438 sampled), but varied from 0–4.8% on Tenerife and was usually low (0–2%) on the other islands. On Tenerife, infected larvae were present at 11 out of 17 plantations sampled. The prevalence of infection in larvae on bananas grown under greenhouse structures was significantly higher (3%) than in open-field sites (1.4%). The ChchNPV-TF1 isolate was the most abundant and widespread of four genetic variants of the virus. Application of 1.0x109 viral occlusion bodies (OBs)/l of ChchNPV-TF1 significantly reduced C. chalcites foliar damage in young banana plants as did commonly used pesticides, both in greenhouse and open-field sites. The insecticidal efficacy of ChchNPV-TF1 was similar to that of indoxacarb and a Bacillus thuringiensis (Bt)-based insecticide in one year of trials and similar to Bt in the following year of trails in greenhouse and field crops. However, larvae collected at different time intervals following virus treatments and reared in the laboratory experienced 2–7 fold more mortality than insects from conventional insecticide treatments. This suggests that the acquisition of lethal dose occurred over an extended period (up to 7 days) compared to a brief peak in larvae on plants treated with conventional insecticides. These results should prove useful for the registration of a ChchNPV-based insecticide for integrated management of this pest in banana crops on the Canary Islands.

Changes in nutrient concentrations and leaf gas exchange parameters in banana plantlets under gradual soil moisture depletion

Changes in mineral nutrient concentration, growth, water status and gas exchange parameters were investigated in young banana plants ( Musa acuminata cv. ‘Grand Nain’) subjected to gradual soil moisture diminution. Experiments were performed in glasshouse under controlled temperature, and water stress was imposed by ceasing irrigation for 62 days. The data showed a parallel decrease of leaf gas exchange parameters and soil moisture initiated few days after the imposition of water stress. However, the leaf relative water content (RWC) showed a minor decrease in response to drought. The onset of growth reduction evaluated as plant height, pseudostem circumference, number of newly emerged leaves, leaf area, and leaf and root biomass took place approximately between 34 and 40 days after the beginning of the stress period. In addition, drought did not modify nitrogen and phosphorus concentrations in foliar and root tissues; however, it increased potassium, calcium, magnesium, sodium and chloride in leaves, and only calcium, sodium and chloride in roots. Collectively, the data reveal that banana plants show a drought avoidance mechanism in response to water stress. After a prolonged drought period, leaf RWC was hardly reduced, while gas exchange and growth parameters were reduced drastically. Increasing leaf mineral concentration could have help to maintain leaf RWC due to osmotic adjustment mechanism.

Presence of banana bacterial wilt (Xanthomonas campestris pv. musacearum) in Rwanda

In September 2005, visits were made to five sites within the Gisenyi province in northern Rwanda to investigate reports of a damaging banana disease affecting brewing, dessert and cooking varieties. Symptoms included progressive yellowing and wilting of leaves, shrivelling of male buds, premature ripening and internal discoloration of fruits plus characteristic yellow ooze from the vascular tissue of cut pseudostems. These symptoms resembled those of banana bacterial wilt (BBW) caused by Xanthomonas campestris pv. musacearum (Xcm). A yellow-pigmented bacterium was consistently isolated on yeast extract dextrose calcium carbonate agar from the internal tissues of flower stalks. Four isolates were identified as Xanthomonas campestris by fatty acid (Microbial ID Inc. [MIDI]) and metabolic (Biolog, Inc) analyses [ID probability score approx. 0·9]. Molecular studies using rep-PCR (Louws et al ., 1994) with ERIC and BOX primers confirmed that isolates had an identical DNA fingerprint to other Xcm isolates from Musa spp. in Ethiopia, Uganda and the Democratic Republic of Congo (DRC) and ensete (Ensete ventricosum) from Ethiopia. Pathogenicity was confirmed by injecting bacterial suspensions of isolate (IMI 393 640) into the stems of six young banana plants. Typical wilt symptoms were observed after three weeks. Bacteria were re-isolated from plants with symptoms and their identity confirmed by rep-PCR analysis. Xcm was first described from Ethiopia in the 1960s, infecting ensete and cultivated banana (Yirgou and Bradbury, 1968) but was only recently confirmed infecting bananas in Uganda and the DRC (Tushemereirwe et al ., 2004; Ndungo et al ., 2006). In Gisenyi province, banana is extensively cultivated in the highland plateaux. The wilt disease has been reported from three districts (Cyanzarwe, Gisenyi, Kanama), though it may have spread more widely. Local farmers report that wilt symptoms were first seen around 2002-2003. The disease may have spread from the DRC when Congolese people fled to Ruhengeri and Gisenyi provinces following the eruption of Mount Nyiragongo in January 2002. There is a regular interchange of people and goods across the Rwanda-DRC border and the first confirmed outbreak of Xcm in the DRC was in Masisi region (Lacs Mokotos), which is close to Gisenyi. This is the first report of BBW in Rwanda and poses a serious threat to banana production, endangering the livelihoods of banana growing households throughout the country. Ethiopian and Ugandan isolates and isolate (IMI 393 640) are held in the CABI Genetic Resource Collection. (Author's abstract).

The role of “effective microorganisms” in the composting of banana (Musa ssp.) residues

Abstract“Effective microorganisms” (EM) are a poorly defined mixture of supposedly beneficial microorganisms that are claimed to enhance microbial turnover in compost and soil. In Costa Rica, EM are used to produce organic compost (bokashi) from banana residues (Musa ssp.). Given the scarcity of scientific data about the effects of EM on the mineralization of plant residues, this study aimed at investigating the effects of EM addition on the decomposition of banana residues during Bokashi production. To this end, the following non‐EM treatments were compared to EM Bokashi: Bokashi produced with water (W), with molasses (M) as an EM additive, and with sterilized EM (EMst). Subsequently, the effects of the resulting Bokashi treatments on the growth of young banana plants were evaluated. Compared with non‐EM controls, the effect of EM on the mineralization of banana material was negligible. Dry‐matter losses of the composts with different EM treatments were similar, with about 78% over 5 weeks. Ergosterol concentration was highest in EM Bokashi (77 µg (g dry soil)–1) and lowest in EMst Bokashi (29 µg (g dry soil)–1). Microbial biomass carbon (Cmic) and microbial biomass nitrogen (Nmic) were both lowest in EM (Cmic = 3121 µg g–1; Nmic = 449 µg g–1), while Cmic was highest in Bokashi produced with molasses (3892 µg g–1) and Nmic was highest in EMst (615 µg g–1). Treatment effects on adenylate concentrations and adenylate energy charge were negligible. Application of all Bokashi variants to young banana plants significantly increased shoot growth under greenhouse conditions compared to plants grown in a control soil without amendments. However, these effects were similar for all Bokashi treatments, even if EM Bokashi increased the K concentrations in banana leaves significantly compared to Bokashi produced with EMst and the control. Bokashi produced with only molasses and EM Bokashi decreased the number of root nematodes under greenhouse conditions compared to the control. Overall, the results confirmed the expected influence of composting on the degradation of organic material and the effect of compost application on plant growth. Hower, under the conditions of this study, EM showed no special effects in this, except for increasing the K concentrations in the leaves of young banana plants.

Presence of banana xanthomonas wilt (Xanthomonas campestris pv. musacearum) in the Democratic Republic of Congo (DRC)

In May 2004, following reports from local farmers of a devastating new banana disease, the first three authors visited Masisi District, 72 km northwest from Goma in North Kivu Province, Democratic Republic of Congo (DRC) (altitude 1700 m above sea level) and diagnosed banana bacterial wilt caused by Xanthomonas campestris pv. musacearum (Xcm). Symptoms were similar to those seen in Uganda (Tushemereirwe et al., 2003) and included: progressive yellowing, wilting and blackening of leaves; yellow or brown vascular streaks throughout the plant; pockets of pale yellow bacterial ooze in airspaces within leaf bases; premature ripening and internal discoloration of fruits; and shrivelling of male inflorescence buds. Inflorescence symptoms probably result from transmission of bacteria by insects, and were uncommon. This may explain the limited spread in DRC since 2001, only c. 10 km from the original focus at Bashali Mokoto village, compared with 400 km in Uganda over the same period (see www.banana.go.ug). As in Uganda, ABB banana genotypes (especially 'Pisang Awak') appear to be the first to be infected, and matooke clones (Musa AAA-EA group) the last. Affected stools do not always die; new suckers emerge and these initially appear healthy but usually become infected from the mother plant, rarely surviving to flowering stage. The epicentre of the outbreak in Masisi was devastated, with total loss of yield and an alarming impact on food security. Using methods described by Tushemereirwe et al. (2004), yellow pigmented bacteria were isolated as almost pure cultures from samples of diseased inflorescence stalks sent to the Global Plant Clinic at CABI Bioscience, UK. Biochemical and molecular characteristics of two isolates were indistinguishable from Xcm from Uganda. Both caused rapid wilting within 7-10 days of inoculation into young banana plants from which the same organism was reisolated. It may be feasible to eradicate this outbreak by destroying affected plants and cleaning up affected fields, combined with removing male flower buds in surrounding healthy plants to prevent insect transmission. However, the first author has recently observed a new disease focus c. 20 km from the first, so continued vigilance and control action will be needed. The origin of these outbreaks is unknown. Until 2001, Xcm was known only from Ethiopia, where it causes disease in enset (Ensete ventricosum) and cultivated banana (Yirgou and Bradbury, 1968, 1974). It is possible that the disease has spread from wild or semicultivated enset plants, which can be found throughout the Masisi region. (Author's abstract).

Aclimatização de mudas micropropagadas de bananeira sob diferentes condições de luminosidade

O objetivo do presente trabalho foi avaliar a taxa de sobrevivência de mudas de bananeira micropropagadas, sob diferentes condições de aclimatização. Mudas de bananeira "Prata-Anã', obtidas por micropropagação, com 2-3 cm de comprimento, foram plantadas em bandejas contendo substrato comercial Plantmax. As bandejas contendo os tubetes foram colocadas sob estufins com cobertura plástica transparente, para aclimatização em diferentes condições de luminosidade. Os tratamentos foram compostos de: T1- Câmara de aclimatização sob cobertura em telhado de amianto; T2- Câmara de aclimatização sob telado, com 50 % de sombreamento, e T3- Câmara de aclimatização coberta com papel tipo Kraft e sob telado, com 50 % de sombreamento. O delineamento experimental foi inteiramente casualizado, com três tratamentos e setenta repetições. As plantas permaneceram por 15 dias nos referidos tratamentos, quando foi realizada a primeira avaliação. Aos 30 dias após o plantio, foi realizada a segunda avaliação. Foram avaliadas as características comprimento da muda, diâmetro do coleto, número de folhas completamente expandidas e porcentagem de pegamento. As características avaliadas foram submetidas à análise de variância, sendo os efeitos dos tratamentos comparados pelo teste de Tukey, a 5% de probabilidade. Na primeira avaliação, observaram-se 100 % de sobrevivência das plântulas nas três condições de luminosidade testadas. Aos trinta dias após o plantio em tubete, as plantas aclimatizadas em estufin sob telado com 50% de sombreamento apresentaram as maiores médias de comprimento, diâmetro e número de folhas, com 4,6 cm, 0,64 cm e 5,5 folhas, respectivamente.

Effect of aluminium on bananas (Musaspp.) cultivated in acid solutions. II. Water and nutrient uptake

Introduction. A previous paper showed that Al in the nutrient solution affected the growth, biomass production and chemical composition of bananas (Musa spp.). This paper aims at providing complementary results on the effect of Al on water and nutrient uptake by young banana plants. Materials and methods . Vitroplants of five cultivars (Grande Naine, Agbagba, Obino l'Ewai, Igitsiri and Kayinja) were grown for 40 d in a phytotron with a temperature close to that of their cropping areas. Dilute nutrient solutions without Al and with 78.5 μ M Al were supplied continuously with peristaltic pumps. Measurements of daily water and nutrient uptake were carried out twice a week. Rhizosphere acidification or alcalinisation were also monitored. Results and discussion . Aluminium reduced plant water uptake and cumulative detrimental effects were observed. After 40 d, water uptake was only 30-40% of the control. Without Al, nutrient uptake (Ca, Mg, K, P, NO3 -N, NH4 -N) increased with time, whereas Al inhibited the uptake of all elements, particularly Mg. As for water absorption, cumulative effects were observed: after 40 d, most nutrient uptake rates were reduced by more than 50% relatively to the control. The plantain bananas, Agbagba and Obino l'Ewai, were more resistant to Al than the others. Changes of temperature are likely to modify Al sensitivity as one cultivar, Kayinja, showed greater Al sensitivity at 28/25°C than at 24/20°C.

Temperature influences the distribution of some nutrients in young banana plants independently of its effect on dry matter

The distribution of N, P, K, Ca, Mg, Na, Cl, Mn, Cu, Zn, Fe and B among parts of vegetative banana plants well supplied with nutrients was examined in plants grown for 12 weeks under 6 temperature regimes ranging from 17 10 °C to 37 37 °C (day/night). As temperature increased, the proportion of dry matter in the leaves increased from 20 to over 50% at the expense of the corm and roots. The proportion of dry matter in the pseudostem was relatively less affected, being 20–25% of the whole plant dry weight under all temperature regimes. Changes in the ratio of C o C w (concentration of nutrient in the organ/concentration in the whole plant) with temperature showed that the distribution of N, P, K, Mg, Cl and Cu closely followed changes in the distribution of dry matter, whereas the distribution of Ca, Na, Mn, Zn, Fe and B within the plant was not so linked. Higher temperature increased the C o C w ratio in corm and pseudostem and decreased it in the roots. Nutrients in the leaves were least affected. The magnitude of the change depended on the nutrient and organ involved, varying from no significant change for Cu and Zn in the leaves to more than a 2-fold decrease of Cl in the roots. The stability of C o C w in the leaves means that they are more suitable than other organs for use in assessing whole-plant nutrient status.

Temperature influences nutrient absorption and uptake rates of bananas grown in controlled environments

We explored the influence of temperature on the concentration of nutrients in banana plants, the nutrient uptake rate, apparent root transfer coefficient ( \\ ̄ ga) and the relationship between accumulation of dry matter and nutrient. Young banana plants ( Musa (AAA group, Cavendish sub-group) ‘Williams’) were grown at six temperature regimes (17/10–37/30°C) in sunlit growth chambers for 12 weeks. The amount of nutrient absorbed was influenced by the amount of growth made, but the link between the two differed from one element to another. Temperatures less than 29 22° C reduced the concentration of all elements in the whole plant, except Fe. Temperature influenced the root uptake rate of B 10-fold; K, Na, Ca, Fe and Zn 3–4-fold; and N, P, Mg, Mn, Cu, Cl 1–2-fold. Among the elements the highest recorded rate was 12 mg g −1 day −1 for K at 33 26° C . The optimum temperature for nutrient uptake rates differed among the elements. This was accounted for largely by greater growth at those temperatures of organs with high concentration of particular elements. The \\ ̄ ga (an estimate of efficiency of uptake) of B varied 12-fold among treatments; K, Ca, Mg, Na, Mn, Zn and Cl varied 3–5- fold and N, P, Cu and Fe varied 2–3-fold. The ratio of relative nutrient accumulation rate, R m, to the relative growth rate, R w, was most stable across temperatures for N and least stable for B and Na. However, the trend was for R m R w to increase as temperature rose, indicating an absorption of nutrients greater than might be expected from a change in growth rate as temperature increased, and a decreased efficiency in their utilization for plant growth.