Response of eight sugarcane cultivars to glyphosine and glyphosate ripeners

Studies were conducted on eight sugarcane (Saccharum spp. hydrid) cultivars during the 1982–83 (plant crop) and 1983–84 (ratoon crop) growing seasons to determine the effects of glyphosine (Polaris) (N,N-bis (phosphonomethyl) glycine) and glyphosate (Polado) (sodium-N-(phosphonomethyl) glycine) on stalk sucrose content and yield. Difference due to crops (plant vs. ratoon) for sugarcane quality, kilograms of sugar per ton of cane (S/T), sugarcane yield, tons of cane per hectare (TCH), and sugar yield, tons of sugar per hectare (TSH) were significant. Significant differences were found in quality for the ratoon crop and cane and sugar yield in both crops due to ripener treatment. Cultivars in both crops differed significantly in quality and yield. Harvest dates were significantly different for all plant characteristics. Interactions of cultivar by treatment for the plant crop, harvest date by treatment for the ratoon crop, and cultivar by harvest date for both crops for cane quality also were significant. Time from ripener application to achievement of maximum sugar concentration also depended on cultivar. This is important in determining the economic benefits of a ripener treatment. Climatic conditions may also affect the benefits of such applications.Mention of trade name or proprietary product does not imply or constitute an endorsement or recommendation by the USDA or the University of Florida.     

Response of eight sugarcane cultivars to glyphosine and glyphosate ripeners

Studies were conducted on eight sugarcane (Saccharum spp. hydrid) cultivars during the 1982–83 (plant crop) and 1983–84 (ratoon crop) growing seasons to determine the effects of glyphosine (Polaris) (N,N-bis (phosphonomethyl) glycine) and glyphosate (Polado) (sodium-N-(phosphonomethyl) glycine) on stalk sucrose content and yield. Difference due to crops (plant vs. ratoon) for sugarcane quality, kilograms of sugar per ton of cane (S/T), sugarcane yield, tons of cane per hectare (TCH), and sugar yield, tons of sugar per hectare (TSH) were significant. Significant differences were found in quality for the ratoon crop and cane and sugar yield in both crops due to ripener treatment. Cultivars in both crops differed significantly in quality and yield. Harvest dates were significantly different for all plant characteristics. Interactions of cultivar by treatment for the plant crop, harvest date by treatment for the ratoon crop, and cultivar by harvest date for both crops for cane quality also were significant. Time from ripener application to achievement of maximum sugar concentration also depended on cultivar. This is important in determining the economic benefits of a ripener treatment. Climatic conditions may also affect the benefits of such applications.     

Growth Parameters of Yield of Plantain (Musa cv. AAB)

The performance of the crop plant and the ‘ratoon’plant (lateral shoot succeeding the harvested main shoot) of65 medium-sized False Horn plantains (Musa cv. AAB) was studiedby measuring vegetative and inflorescence (bunch) parameters.From significant regressions between different parameters itappears that taller pseudostems produce leaves at a faster rate,flower earlier and produce heavier infructescences which needmore time to mature. A high yield is determined by vigorousinitial growth of the planted sucker (lateral root). Beforeflowering, there is no sink competition between ratoon and mainpseudostem growth, and fast-growing main pseudostems are accompaniedby fast-growing ratoons. After flowering, competition occursbetween the fructifying inflorescence, a preferential sink andthe ratoon. The results indicate that plantain should not beconsidered as an annual crop. Growth, development, production parameters, bananas, plantains     

Spacing and sucker management in the commercial plantain production in the rainforest belt of Nigeria

Maintaining one, two or three suckers per rootstock in plantain (Musa spp.) populations of 2000, 1600 and 1333 per hectare were evaluated for sustained yield in the orchard for three harvest cycles. The yield per plantain for the plant crop was not significantly affected by either population density or the number of suckers maintained. However, the total yield significantly increased with the increased plantain population per hectare. The yield per plantain decreased in the first and subsequent ratoon crop harvests as the original plantain population per hectare doubled or tripled when two or three suckers were maintained respectively per rootstock. Although the total yield per hectare was significantly higher when two or three suckers were maintained per rootstock, the individual bunch weight and the fingers significantly decreased to an unacceptable size to the consumers. Establishment of orchards at 1600 plantains per hectare with two suckers maintained per rootstock in subsequent cycles produced consistently good quality marketable fingers and sustained high yield.     

Field evaluation of micropropagated bananas derived from plants containing Banana Bunchy-Top Virus

Micropropagated bananas derived from Banana Bunchy-Top Virus (BBTV) infected plants, but displaying no symptoms of the disease, were established in the field. They were grown for three years and produced a plant crop and ratoon crops. No disease symptoms were observed. There was uncertainty as to whether

Cryopreservation for the elimination of cucumber mosaic and banana streak viruses from banana (Musa spp.)

The utilisation of cryopreservation for the eradication of cucumber mosaic virus (CMV) or banana streak virus (BSV) from Musa spp. was investigated. Banana plants, cv. Williams (AAA, Cavendish subgroup), were mechanically infected with CMV or naturally infected with BSV, and proliferating meristems were produced from the infected plants. Excised meristematic clumps were cryopreserved through vitrification using PVS-2 solution. The health status of regenerated in vitro plants was first checked by means of ELISA. The putative virus-free material was subsequently tested a second time following greenhouse acclimatisation. The frequency of virus eradication for CMV and BSV was 30% and 90%, respectively, following cryopreservation. In comparison, the frequency of virus-free plants regenerated directly from highly proliferating meristems, corresponding to a spontaneous eradication rate, reached 0% and 52% for CMV and BSV, respectively. The conventional meristem culture resulted in 0% CMV-free plants and 76% BSV-free plants, while the cryoprotective treatment resulted in 2% CMV-free plants and 87% BSV-free plants. To understand the mode of action of cryopreservation for the eradication of viral particles, we examined the structure of the meristem tips by light microscopy. The cryopreservation method used only allowed survival of small areas of cells located in the meristematic dome and at the base of the primordia.     

Variability of responses to 1-methylcyclopropene by banana: influence of time of year at harvest and fruit position in the bunch

To examine the effect of early‐climacteric (postripening) 1‐methylcyclopropene (1‐MCP) exposure on the shelf‐life and quality of green Cavendish bananas (Musa acuminata cv. Williams) from the middle section of the bunch, bananas were harvested bimonthly and treated with 100 μL L^?1 ethylene for 2 consecutive days prior to exposure to 0, 100, 300, 1000, 3000 or 10 000 nL L^?1 1‐MCP for 24 h prior to storage at 22°C. 1‐MCP treatment at a concentration of 300 nL L^?1 or above increased banana shelf‐life significantly compared with the control, regardless of the month in which fruit were harvested except March where a higher concentration was needed (3000 nL L^?1). Fruit harvested in May were the most responsive with a greater than twofold increase in shelf‐life. To examine the effect of fruit position in the bunch on 1‐MCP efficacy, green fruit from the top or bottom of bunches were treated with 100 μL L^?1 ethylene for 2 consecutive days prior to early‐climacteric 1‐MCP (300 nL L^?1) exposure for 24 h at 22°C. In spring and autumn but not in summer, application of 1‐MCP to early‐climacteric fruit was more effective in fruit from the top than in those treated from the bottom of the bunch, increasing shelf‐life. Firmness of 1‐MCP‐treated fruit was up to 19% greater than that of the control across the year, except in fruit from the bottom of the bunch. Given that 1‐MCP is less effective in extending the shelf‐life of summer‐harvested fruit (particularly those from the bottom of the bunch), we conclude that preharvest conditions and fruit position in the bunch affect their responsiveness to ethylene and their behaviour during the ripening process.     

Breaking the Cycle of Xanthomonas campestris pv. musacearum in Infected Fields through the Cultivation of Annual Crops and Disease Control in Adjacent Fields

Cultivation of non‐host crops after uprooting Xanthomonas campestris pv. musacearum (Xcm)‐infected banana plants has been advocated for breaking Xanthomonas wilt disease (XW) cycle in fields. Knowledge on the interaction of these crops with Xcm is limited. Maize, beans and sweet potato were planted after uprooting Xcm‐infected banana plants in Rwanda and eastern Democratic Republic of Congo (DR Congo). A weed fallow (mixed species) served as the control. After one, two and/or four break‐crop or fallow seasons, healthy plantlets were replanted and monitored for XW for 12–24 months. XW status in adjacent fields was monitored, and diseased stems within 100–300 m radius of the two‐ and four‐season experiments were uprooted. In Rwanda, soil and plant parts from the one‐season experiments were sampled for Xcm isolation and Xcm‐like colonies confirmed with Xcm‐specific primers using PCR. Pathogenicity tests were performed to confirm the ability of the PCR‐positive isolates to infect healthy banana plantlets. XW was observed in all the one‐season experiments, with higher cumulative incidences in maize and bean plots. However, no similar trends were observed in the two‐season experiments, with a 6–8% incidence observed only in bean and potato plots in DR Congo. Lengthening time under break crops to two and four seasons, respectively, reduced the incidence to 3% and zero in Rwanda and 0–8% in the two‐season experiments in DR Congo. Incidence in the first‐season experiments highly correlated (R = 88) to that in the adjacent fields, suggesting possible re‐infections from these fields. Two season with break crop plus collective XW control are recommended in these agro‐ecosystems. PCR‐positive Xcm‐like colonies from break crops only induced localized cell death on banana, while PCR‐positive isolates from symptomatic banana plants caused full XW symptoms. Cross‐infection/inoculation studies under controlled conditions are still needed to conclusively elucidate Xcm interaction with these crops.     

Disease spread patterns of Banana streak virus in farmers, fields in Uganda

Three surveys were conducted to establish the disease spread patterns of Banana streak virus (BSV) in farmers, fields in Uganda. Transects were traced both across the fields and from infection foci within a field. BSV incidence in adjacent quadrats was also determined to quantify statistically the spatial relationships of infected plants in the fields. Severity assessment along transects across fields revealed clusters of plants with moderate to high severity and clusters of plants with no BSV or low severity. Symptom severity decreased away from foci of infection (b=?0.014; P=0.0081). Observed frequency of infected quadrat counts differed from corresponding expected frequency of infected quadrat counts (Poisson, s distribution, x²; P<0.01). BSV– infected plants, therefore, were aggregated in well‐established fields. Aggregation of infected plants in farmers, fields and the decrease of severity away from infection foci suggest the likely involvement of a slow moving vector in BSV transmission.     

Plant domestication disrupts biodiversity effects across major crop types

Plant diversity fosters productivity in natural ecosystems. Biodiversity effects might increase agricultural yields at no cost in additional inputs. However, the effects of diversity on crop assemblages are inconsistent, probably because crops and wild plants differ in a range of traits relevant to plant–plant interactions. We tested whether domestication has changed the potential of crop mixtures to over‐yield by comparing the performance and traits of major crop species and those of their wild progenitors under varying levels of diversity. We found stronger biodiversity effects in mixtures of wild progenitors, due to larger selection effects. Variation in selection effects was partly explained by within‐mixture differences in leaf size. Our results indicate that domestication might disrupt the ability of crops to benefit from diverse neighbourhoods via reduced trait variance. These results highlight potential limitations of current crop mixtures to over‐yield and the potential of breeding to re‐establish variance and increase mixture performance.