The cornerstones of HARC's sugarcane research program were to improve sugarcane varieties through breeding and selection, to develop sound agronomic practices, and to control insects and diseases.
Sugarcane Breeding and Selection HARC maintains a breeding and selection program to identify sugarcane cultivars with high yield potential and resistance to sugarcane diseases and test them for site adaptability.
Producing sugarcane seedlings each year from genetically diverse parents (breeding clones) is essential for developing high yielding disease and insect resistant sugarcane cultivars for commercial planting by the sugar industry. About 1,200 Hawaii-produced breeding clones and 800 imported breeding clones are currently maintained in field plots at the HARC Breeding Station at Maunawili on Oahu. Advanced selection and yield testing of seedlings was accomplished in cooperation with island plantations. It requires about 10 to 15 years of testing to identify a new sugarcane cultivar.
Genetic engineering and molecular techniques have been developed as plant breeding tools. These include genetic transformation, tissue culture, and molecular marker techniques.
Agronomy and Weed Control It's important to control weeds in sugarcane fields as they compete for nutrients and water which can affect the sugarcane's vigor and ultimately the yield. Recently, field trials installed at the plantations yielded information on the most effective herbicide combinations of compounds that are registered for use in sugarcane and the rate required to give effective weed control. Several new herbicides that are not yet registered for use in sugarcane were also tested in small experimental plots. Mineral nutrition studies are also conducted to determine optimum rates and timing of fertilizer application.
Insect Control Hawaii's sugarcane industry has successfully controlled sugarcane insect pests through biological control rather than using pesticides. This strategy has proved itself over 100 years and has been used as a model for many other crops.
Presently, yellow sugarcane aphid (YSCA) is a prevalent pest in sugarcane fields, although the extent of damage it causes has not yet been quantified. HARC and Dr. Messing of the University of Hawaii's Kauai Research Center are cooperating on a project to introduce effective aphid parasitoids into Hawaii. The first aphid parasitoid, Aphidius colemani (Viereck) (Aphidiidae: Braconidae) introduced in April 1996 was not effective on YSCA but was highly effective on the melon aphid. When an effective YSCA parasitoid which passes quarantine and host range studies is introduced, field release will be conducted on Maui and Kauai at sugar plantations.
Lesser cornstalk borer (LCB) is not currently causing substantial damage in plant cane; however, we expect damage to increase with greater emphasis on ratooning. (Good cultural practice, especially timely irrigation in ratoon fields, will help reduce damage.) In anticipation of this, the sugarcane cultivar 73-6110 was transformed with a Bt gene. Laboratory feeding studies indicated that LCB-resistance was conferred. A decision on whether to deploy the transformed cultivar is pending.
Disease Control HARC's disease control program for the sugar industry develops assessment methods, identifies and controls disease problems, and screens breeding material for resistance to important diseases. Currently, several sugarcane diseases are of concern:
Eyespot Disease-is caused by the fungus Bipolaris sacchari and transmitted by air-borne spores which germinate and make leaf lesions resulting in yield lost due to reduced functional leaf area. New sugarcane clones are being screened for resistance to the pathogen using a toxin from the fungus to inoculate plants.
Smut Disease-is caused by the fungus Ustilago scitaminea which infects the plants systemically, stunting the shoots, and eventually killing the plant. New sugarcane varieties are screened for smut resistance by inoculating seed pieces of all clones with fungus spores and eliminating those that become infected. These are again tested for smut resistance under natural conditions by being planted among other infected plants and exposed to the airborne spores as they would be in nature. All seed cane is treated by soaking in hot water for 20 min at 52° C to kill the fungus. Seed farms are inspected periodically.
Yellow Leaf Syndrome-is-now a recognized virus disease of sugarcane which is transmitted by aphids and causes cane tonnage losses. The development of a tissue-blot immunoassay (TBIA) for detection of the causal virus (ScYLV) has made it possible to screen large numbers of plants accurately and quickly for the infection. All of the main commercial varieties were surveyed on the Hawaiian plantations and the virus was found to be more widespread than had been expected. Most infected sugarcane remains asymptomatic until it is placed under stress conditions. Inoculations with viruliferous aphid vectors determined that some sugarcane varieties are resistant to the virus. No specific control measures are practised.
Ratoon Stunting Disease-is a systemic bacterial infection that is generally symptomless, but results in cane tonnage losses which may be severe. The pathogen is Leifsonia xyli subsp. xyli. It is kept to a very low level in Hawaii by screening seed fields for infection using an immunological diagnostic technique and giving all seed a hot water treatment for 20 min at 52° C before planting.
Leafscald Disease-is caused by the bacterium Xanthomonas albilineans. Symptoms are white leaf streaks that coalesce and turn brown, eventually killing the plant. They appear on infected plants during cooler times of the year. In Hawaii, outbreaks occur during some years and not others. An immunological diagnostic technique can detect the bacterial infection in plants. However, control is maintained by giving seed a hot water treatment for 20 min at 52° C before planting. Some sugarcane varieties are resistant, but this cannot be counted upon for control because new strains of the bacteria occasionally appear.
HARC cooperates with many countries exchanging research findings and sending sugarcane varieties to them for disease testing. Sugarcane varieties developed in Hawaii are exchanged with other countries for breeding and all quarantine and disease protection protocols are strictly followed.
For more information, contact Dr. Chifumi Nagai Phone/fax: (808) 621-1385/621-1399
'HARC begins investigating the tropical oilseed-bearing tree Jatropha curcas'
In late-2006, HARC initiated the first test plot in Hawaii of Jatropha curcas, a tropical tree that has received a great deal of attention for its potential to provide vegetable oils for the biofuel industry. This work was supported by the Hawaii Farm Bureau Federation through a $37,000 grant stemming from a 2006 proposal entitled 'Jatropha curcas establishment for future biodiesel production.' Throughout 2007, HARC expanded its efforts in jatropha research to meet the demand for information surrounding this potential crop.
HARC's jatropha research began with the establishment of trees from seed of Madagascar origin. Further field plots were established from seed of Indian origin. In late 2007, plots of trees from these two sources and from locally available Hawaiian seed were also established. The test plantings were designed to monitor plant density as the trees mature. The first year of growth provided a field laboratory to begin evaluating the growth of jatropha in Hawaii's leeward environments. We have been able to achieve year-round flower and fruit production through supplemental irrigation and minimal fertilization. Two significant insect pests were identified in the test plantings: the papaya mealybug (Paracoccus marginatus) and the castor semilooper (Achaea janata). There also appear to be other viral and fungal pathogens that may affect jatropha's growth and reproduction cycles.
Hawaii's leeward climate zones appear capable of producing sapling jatropha trees that can begin to produce fruit within the first 5 months of growth. Although the yields are not economically significant, this rapid growth and reproduction will allow HARC researchers and their collaborators the opportunity to rapidly make improvements through traditional breeding procedures.
One of the most significant needs for research in jatropha is the development of uniform morphology, development and yield. Early plantings suggest that there is extreme genetic variability across populations. Selections and isolated plantings of superior materials are in planning stages to increase the availability of uniform seed material for further research efforts. Uniformity in established plantings will directly affect the ability to automate field operations and harvesting.
'HARC scientists take international trip to study Jatropha curcas'
In October 2007 Assistant Agronomist Mike Poteet and retired HARC Vice-President Dr. Robert V. Osgood traveled to multiple international locations to collect information on the research and production of Jatropha curcas. The trip was part of a project that HARC is partnered with the University of Hawaii's College of Tropical Agriculture and Human Resources for start-up research into tropical oilseed-bearing trees. The project entitled 'Terrestrial Oilcrops for Biodiesel Production' was granted $150,000 by the Hawaii Department of Agriculture in the summer of 2007. The international trip was designed to gain exposure to historic production areas, recent efforts at commercialization, and meet with other researchers at their field stations.
The first visit on the trip was to the African island-nation of Cape Verde. Cape Verde has a long history of small-scale production of jatropha oil for local use and export to European markets. Those limited supplies of oil were used for soap production in Europe and for lighting the small towns and cities of Cape Verde. Although the majority of commercial production ended in the 1970's, jatropha trees are still looked to as a resource in reforestation efforts. Cape Verde's national agricultural research station, INIDA, served as hosts for the visit and will be supplying some materials for future research projects in Hawaii.
Following the visit to Cape Verde, HARC's staff visited D1 Oils in London and the University of Hohenheim in Stuttgart, Germany. D1 Oils is a world leader in the commercial development of jatropha research and production with operations in Africa, South America, and Asia. The University of Hohenheim is home to Dr. Klaus Becker, an international leader in jatropha research in tropical regions over the last two decades.
From Europe, Dr. Osgood and Mr. Poteet traveled to India for a week's worth of visits. Starting in southern India at Tamil Nadu Agricultural University (TNAU), tours were given of field trials and extraction equipment. TNAU has been declared the Centre of Excellence for Biofuels by the Indian government. Their ties with local growers, processors and industry representatives provided an excellent opportunity to learn more about India's growing interest and investment into jatropha as a biofuel feedstock. While in Tamil Nadu, visits were also made to D1 Oils' regional research station and Bannari Amman's industrial site where jatropha oil extraction and transesterification are taking place.
From southern India, HARC scientists traveled to central India to visit several field sites of CleanStar Energy. CleanStar Energy is a private firm developing their own research and commercialization ventures to determine the economic feasibility of jatropha production in marginal lands across India. CleanStar served as hosts throughout the entire India trip, providing invaluable assistance in networking and travel.
Lastly, a brief tour of Haryana Agricultural University's Bawal Research Station was given. Researchers at Bawal have been studying jatropha as part of an agro-forestry system for nearly 10 years. The most potential for inter-cropping within jatropha and other oilseed-bearing trees comes within the first 2-3 years of growth when tree size is still relatively small and yields have not reached their full potential. Fully mature trees (~10 years old) were observed in an area that could be described as having extreme climate conditions (115?F in summer and $lt; 10?F in winter). This climate also dictates that superior trees be selected based on number of fruit clusters produced per branch per year. By isolating their most important production characteristic, Bawal scientists have been able to manage their selection efforts more effectively.
The final stop of the trip was at the University of the Philippines Los Banos (UPLB). UPLB has recently begun to collect jatropha planting materials from across the country to evaluate at their main campus in Laguna. Through government and private industry support, UPLB has plans to expand their research efforts in field production, oil extraction, and transesterification. Jatropha has been used by villagers in the Philippines for various purposes over many decades. Utilizing information from parts of the world on the tree's varied uses will help develop research that identifies valuable co-products to support the possible commercial production in Hawaii and elsewhere.
The remainder of the HDOA project with the University of Hawaii began in 2008 as multiple test sites were selected for different oilseed-bearing trees. Other trees of interest include Elaies guineensis (African oil palm), Aleurites moluccana (kukui nut), Moringa oleifera (kalamungay), and Pongamia pinnata (karanja). Plantings of these species were made across the State to compare climatic and soil effects on the potential productivity of each species. These test plots will help lay the foundation for the necessary research on perennial oilcrops in Hawaii.
Since that time, several experiments have been installed to determine the best agronomic practices for jatropha. A collection of jatropha from around the world is being studied to determine performance in Hawaii's diverse climate and soils.
Promising trees from several origins were selected and vegetatively propagated in isolation plots. The seeds where collected from these trees to determine the effect of isolated tree seed material on uniformity of height and branching structure of jatropha. Yield data is also being collected from these plots to observe seasonal variation in production and productivity over time.
Irrigation trials were installed to look at jatropha's drought tolerance characteristics as well as their effect on yield production. High and low rates were used in 2 separate experiments and this data was able to offer interesting insight into the effect of seed origin on drought tolerance characteristics. Drought tolerant varieties as well as water loving varieties have been identified. Another irrigation experiment installed in 2011 will examine different levels of water stress and its effect on yield production as well as fruiting synchronization.
A pruning experiment was installed and has been monitored for almost 3 years. The results hypothesized have not been realized. While pruning did in fact lead to a higher number of branches per tree, it also had a detrimental effect on yield. The yield of the pruned trees has yet to catch up to the yield of the unpruned trees. This significant setback in yield could be due to severity of pruning at early stages of growth. This will be examined in future pruning trials.
A plot has been established with plant material from China which is said to have higher oil content than that of other varieties. This as well as a supposed non-toxic variety from Mexico will need oil content and toxin analysis. The Mexican variety has heavy pest infestation and very low fruit production. A male sterile tree with desirable characteristics has been identified and will be used for future breeding.
For more information, contact Jamie Barton Phone/fax: (808) 677-5541