2IMPORTANCE of SWEET POTATO to BAMC & BARBADOS Highest income earner among food crops at BAMC.Excellent crop for use in rotation with sugar-cane.Occupies large land areas.One of the few domestically produced commodities that is competitive with the imported product.
3CONSTRAINTS Limited information regarding yields of local cultivars. Prevalence of large tubers (<500g) which are rejected by average householder.Few tubers per plant.Difficult to forecast yields per unit area.
4RATIONALETo have an increase in the amount of marketable tubers produced at the BAMC.BAMC’s sweet potato is planted on single rows with 1 to 1.5 ft intra-row spacing and 5 ½ ft inter-row.As spacing increases, the total number of tubers decreases, while the yield of larger tubers increases. (Schultheis, Walters and Adams, 1999).
6OBJECTIVESTo determine the effect of cultivar and single- and double-row planting on the yield of four sweet potato cultivars.To determine average yield per acre for each cultivar.
7METHODOLOGYTrial established at Groves, St. George; smectoid clay, average drainage, responds well to tillage.Split plot design.Four (4) cultivars used:‘Caroline Lee’‘CBS 32’‘CBS 49’‘C104’
8Single-row: 1 ft intra-row; 5 ½ ft inter-row; middle of bed. Double-row: 1 ft intra-row; 2 rows on single bed 1 ½ ft apart.Fertilized with MAP at planting (2 bags/ acre).Tubers were harvested when the following were observed:Vine senescence.Flowering.Exudation of white latex from cut tuber.
9Description of cultivars used Skin ColourFlesh ColourShape of TuberTime to Maturity1.‘Caroline Lee’White/ CreamRound3 - 4 months2.‘CBS 32’Red-BrownDeep OrangeOval3.‘CBS 49’CreamOrangeElongated3months4.‘C104’Red
17EFFECT OF CULTIVAR ON YIELD Significant effect on tuber count/ plant, length and width of tuber (mm) and the average weight per tuber (g).‘C104’ showed the greatest yield potential.‘C104’ had the lowest number of tubers per plant at 4.9, highest average weight/ tuber (230.4 g), highest total weight of tubers per plant at g.
18Cultivar ‘CBS 32’ averaged the highest number of tubers per plant at 6 Cultivar ‘CBS 32’ averaged the highest number of tubers per plant at 6.5 but lowest average weight/ tuber of g and the lowest total weight of tubers per plant (876.4 g).The average weight of the tubers from all cultivars < 500 g.Tubers would be acceptable on the fresh market for household consumers.
19Average Weight/ Tuber (g) Total Weight of Tubers per Plant (g) Effect of cultivar on yieldParameterTuber Count/ HoleLength (mm)Width (mm)Average Weight/ Tuber (g)Total Weight of Tubers per Plant (g)‘Caroline Lee’5.2±2.2 b108.0±30.4 a61.0±14.0 a194.5±90.4 a957.2±467.1‘CBS 32’6.5±2.4 a104.6±13.3 a51.1±9.1 c138.8±61.2 b876.4±484.7‘CBS 49’5.0±2.4 b130.3±22.9 b53.0±15.3 bc220.3±170.7 a946.5±568.9‘C104’4.9±1.8 b125.4±57.5 b58.2±29.6 ab230.4±134.6 a1008.1±525.6Average5.4±2.3117.1±36.655.8±18.9196.0±126.0947.0±512.0
20THE EFFECT OF SINGLE- AND DOUBLE-ROW PLANTING ON YIELD Significant effect on the all parameters of yield with the exception of width (mm).With an increase in rows per bed, there was a subsequent decrease in yield.The increase in rows resulted in increased competition for limited resources (Schultheis, Walters and Adams, 1999).Lead to production of smaller tubers.
21Effect of single- and double-row planting on yield ParameterTuber Count/ HoleLength (mm)Width (mm)Average Weight/ Tuber (g)Total Weight of Tubers per Plant (g)Single-row6.3±2.3 a124.7±31.2 a58.9±13.9246.7±160.4 a1298.7±573.4 aDouble-row5.0±1.9 b113.3±38.6 b54.3±20.9170.7±95.6 b771.2±370.7 bAverage5.4±2.3117.1±36.655.8±18.9196.0±126.0947.0±512.0
22THE EFFECT OF THE INTERACTION OF CULTIVAR AND SINGLE- AND DOUBLE-ROW SPACING ON YIELD For most parameters, there was a decrease in the value from the single-row planting to double-row.The percentage change in the tuber count/ hole ranged from 1.9% for ‘CBS 49’ to 28.1% for ‘Caroline Lee’.‘CBS 49’ is less responsive is terms of the number of tubers it produces with increased competition; cultivar trait.
23Effect of interaction of cultivar and single and double-row planting on yield % Change* in Tuber Count/ Plant% Change in Length of Tuber% Change in Width of Tuber% Change in Average Weight/ Tuber% Change in Total Weight of Tubers/ Plant‘Caroline Lee’(28.1)(21.3)0.7(35.7)‘CBS 32’(27.5)2.7(7.6)(16.8)(43.5)‘CBS 49’(1.9)(10.7)(26.2)(31.4)(44.7)‘C104’(18.1)(2.4)4.1(16.7)(38.5)Total(20.6)(9.1)(7.8)(30.8)(40.6)
24Projected average yields per acre CultivarPlants per Acre(Single-Row)Average Yield per Acre (kg) – Single-Row(Double-Row)Average Yield per Acre (kg) – Double-Row% Increase in Yield‘Caroline Lee’Approx.7 9209945.115 84028.7‘CBS 32’9775.713.0‘CBS 49’10.5‘C104’23.0
25Total yield per acre (kg) increases from single- to double-row planting for each cultivar. The doubling of the number of plants within the acre aided the increase in the total yield per acre.Although these increased yields are encouraging, an economic analysis of the spacing data should be undertaken to determine true benefit (Schultheis, Walters and Adams, 1999).
26CONCLUSIONS‘C104’ showed greatest yield potential while ‘CBS 32’ shows the least.Double-rows resulted in lower yields per plant among sweet potato cultivars but resulted in increased average yields per acre.Both single- and double-row planting resulted in tubers that are ideal for sale on the local fresh market.Suggestions should not be made toward double-row planting for an increase in yield until an economic analysis of all factors is conducted.
28RATIONALE “Technical efficiency”. Measures the ability of a farm to obtain maximal output from a given set of inputs (output-oriented measures); or use the minimum feasible amount of inputs to produce a given level of output (input-oriented measures).”
29OBJECTIVESTo quantify economic feasibility of double-row planting of sweet potato as a production method within the BAMC setting.
31ENTERPRISE BUDGET Rain-fed double-row production on a per acre basis. Revenue sweet potato-1584(4) rods per $10.00 per rod = $The cost per acre of growing double-row sweet potato is $A return of $ is made from in field sales at the farm gate from this activity.
32Partial Budget: Substitution of one acre of sugar cane for one acre of double-row sweet potato LOSSESGAINSIncome LostNew IncomeOne acre of 25 $ per tonne $One acre of sweet potatoes 1584 rods per $10:00/rod $New CostsCosts savedDisc ridging/ acre of sweet potatoes =$49.25Manual weeding /acre of sweet potatoes2 manual weeding-4 $100.00=$200.00Ploughing 1 pass/acre of sugar cane =$71.64Rock picking/ acre of sugar cane =$98.87Fertilizer application/acre of sugar cane =$421.542 manual sprayings of sugarcane =$Pest/ disease Control of sweet potatoes –pesticide control- 2 applications $ 75.36Spring-tining/ acre of sugar cane =$13.25Infield sales of sweet potatoes 1employee( 5 days )= $323.20Mechanical reaping/acre of sugar cane =$841.12Total Costs: $Total benefits: $Net gain $Net lossTOTALS: $$
33Crop Biol. yield/ acre (kgs) Sales Rev. Cost of Product Net Returns PriceUnit(kg)Cost/Unit(kg)Ave. Yield per rod/kgs(Rod)Net returns% Returns‘C. Lee’12798$15840$2826$13013$1.23$0.228.08$1.78$1.0182.15‘CBS 32’11048$1.43$0.266.98$1.18‘CBS 49’11807$1.34$0.247.45$1.10‘C104’13212$1.20$0.218.34$0.98
34CONCLUSIONSDouble-row sweet potato production is a land saving device with tangible output and revenue enhancing benefits.Local and international research indicates that double-row sweet potato production results in a more marketable tuber with enhanced saleable value.Double row sweet potato production has the potential to increase revenue gained from sales on a per acre basis to the producer.
35RECOMMENDATIONSReplication of the double-row sweet potato study within different agro-ecological areas to closely examine links between individual cultivars and yield.Full commercialization of the double-row system of production by BAMC food crop unit, once further agronomic and economic research and evaluation validates its productive worth to BAMC.
36ACKNOWLEDGEMENTS Dr. S. Bellamy – Unit Head, ARVTU. Technical and Field Staff, ARVTU.CBS – Supply of planting material.