Bộ Nông nghiệp Phát triển nông thôn (MARD) 008/07VIE Selection and development sweet potato varieties with high root quality for food processing in Northern and Central of Vietnam MS4 Evaluation and selection of new sweet potato varieties in Bac Giang, Thanh Hoa and Quang Tri 2008-2009 July 2008 Institute Information Project Name Vietnamese Institution Vietnamese Project Team Leader 008/07VIE_Commercial and High Quality Cultivars of Root and Tuber Crops for Processing Purpose in the Northern and Central Vietnam Food Crops Research Institute Food Crops Research Institute A/Prof Dr Nguyen Van Tuat Australian Personnel Faculty of Agriculture, Food and Natural Resources, University of Sydney Prof Dr Les Copeland Date commenced 02/2008 Completion date (original) 12/2009 Completion date (revised) 02/2010 Reporting period First six months Australian Organisation Contact Officer(s) In Australia: Team Leader Prof Dr Les Copeland Name: Professor Position: Organisation Faculty of Agriculture, Food and Natural Resources, University of Sydney Telephone: Fax: Email: +61 9351 2935 + 61 9351 2945 l.copeland@usyd.edu.au In Australia: Administrative contact Annette Vervoort Name: Adm Assistant Position: Organisation Faculty of Agriculture, Food and Natural Resources, University of Sydney Telephone: Fax: Email: 61 9351 8795 61 9351 4172 a.vervoort@usyd.edu.au In Vietnam A/Prof Dr Nguyen Van Tuat Name: Director Position: Organisation Food Crops Research Institute Telephone: Fax: Email: 0320 716395 0320 716385 vantuat55@vnn.vn I OBJECTIVES In the project of "Selection and development sweet potato varieties with high root quality for food processing in Northern and Central of Vietnam”, the objectives are: 1) Select sweet potato varieties for the purpose of food processing from Food Crops Research Institute with ability to adapt to farming conditions in Northern and Central regions in Vietnam 2) Develop and evaluate some methods of processing sweet potato root (manufacturing processes of starch, chips and wine) 3) Develop methods to ferment sweet potato vine and leaves used for livestock feeding by local farmers 4) Strengthen the research capacity of the Vietnamese staff in Science and Agriculture, extension of techniques to improve quality of seed and plant breeding, technologies of crop preservation and processing and quality inspection methods of finished products 5) Improve understanding of farmers to expand the technology for plant protection of sweet potato as part of sustainable farming systems 6) Establish model sites to demonstarte good breeding seeds, advanced production technology and to organise scientific conferences in order to share knowledge with farmers It is necessary to conduct research with new sweet potato varieties and advanced technology in Bac Giang, Thanh Hoa and Quang Tri priovinces from 2008 to 2009 in order to select suitable sweet potato varieties sduited to the environmental conditions of each region II AIMS Select the best one or two sweet potato varieties with high yield and good quality for the provinces of Bac Giang, Thanh Hoa and Quang Tri III RESEARCH METHODS AND SCOPES 3.1 Methods 3.1.1 Location Food Crops Research Institute Bac Giang (Bich Son, Viet Yen, Ngoc Chau, Tan Yen, Mai Trung, Hiep Hoa) Thanh Hoa (Nguyên Binh, Tinh Gia, Quang Luu, Quang Xuong, Dong Thanh, Dong Son) Quang Tri (Vinh Thai, Vinh Linh, Gio Hai, Gio Linh, Hai Quy, Hai Lang,) 3.1.2 Materials Ten varieties were collected from Food Crops Research Institute Hoang Long and local sweet potato varieties were the control samples 3.1.3 Experiment type - Randomized complete block design (RCBD) - Study area: 11 varieties x replications x 15 m2 = 660 m2 - Protection area: 340 m2 - Total: = 1,000 m2 3.1.4 Experimental treatments Replication Kl5 KB1 No HT2 TM1 VC.01 VC.68-2 VC.97-6-2 VC.04-24 VC.02-193 Hoang Long Replication No HT2 VC.02-193 KB1 Hoang Long KL5 VC.04-24 VC.01 TM1 VC.97-6-2 VC.68-2 Replication Kl5 KB1 VC.97-6-2 VC.04-24 TM1 VC.02-193 VC.68-2 No HT2 VC.01 Hoang Long Replication VC.97-6-2 TM1 VC.01 VC.04-24 Kl5 KB1 No Hoang Long HT2 VC.68-2 VC.02-193 3.1.5 Planting method - Cut and plant sweet potato root with the clean tools in all of the locations - Distance: the distance between two plants in a row was 0.2 m and the density was 40,000 plants/ha - Align the plant vertically to the bed surface 3.1.6 Planting time: Winter and Spring 2008-2009 Thanh Hoa and Bac Giang: 5-10th October, 2008 Quang Tri: 15-20th December, 2008 3.1.7 Fertilization method Fertilizer Cattle manure Urea Lan Super Kali - kg /ha 15,000 150 550 220 Kg(NPK)/ha 60-70 kg N/ha 90-100 kg P/ha 120 kg K/ha Mix all of the cattle manure and Lan super as well as 30% of Urea and 30% of Kali for treament before planting - Half of the remaining Urea and Kali lefts was fertilized 20-25 days after planting The other half was added in 40 to 45 days after planting 3.1.8 Plant protection Identify and control pests: - Take out the black cut worm (Agrotis ipsilon) by hand or using recommended pesticide - Using trap or pesticide for beetles (Cylas spp.) 3.1.9 Irrigation - Apply irrigation days after fertilizing 3.1.10 Harvesting data collection - For each treatment, sweet potato roots were harvested from a m long section in the middle of the bed - Sweet potato roots were inspected with criteria such as insects, diseases, breakage for each treatment - Counting the number of roots for each treatment - Weighing and grading roots: small 100g 3.1.11 Participants - Food Crops Research Institute: Nguyen Van Tuat, Truong Cong Tuyen, Nguyen Dat Thoai, Truong Thi Thuy, Nguyen Phan Anh, Tran Quoc Anh, Do Thi Lieu, and Nguyen Thi Hien - The University of Sydney: Les Copeland, Peter Sharp, Richard Trethowan 3.12 Statistic analysis - Data were collected by the Vietnamese participants and analyzed statistically by the Australian experts 3.2 Research scope - Describe the nature and origin of new sweet potato varieties - Describe morphological characteristics of 11 studied varieties - Investigate the effect of climate on sweet potato growth in three provinces of Bac Giang, Thanh Hoa and Quang Tri in 2008-2009 - Evaluate and and select new potato varieties in Bac Giang based on quality and yield - Evaluate and select new potato varieties in Thanh Hoa based on quality and yield - Evaluate and select new potato varieties in Quang Tri based on quality and yield IV RESULTS 4.1 Nature and origin of new sweet potato varieties 4.1.1 Origin of sweet potato selection Variety KL5 The variety KL-5 was derived from the open pollination of the variety Number This variety has medium vine and leaves, deeply lobed leaves It is able to grow strongly and regenerate quickly and is suitable for trimming vines and leaves periodically The vines and leaves are soft and sweet which is suitable for livestock feed Vine-leaf yield is 25-30 tonnes/ha The root yield is very high, normally achieving an average 20–22 tonnes/ha, intensively reaching 28-30 tonnes/ha Variety number The variety Number was created from 1b Mien Nam × Bat Luan Xuan This variety has high yield, short growth period 90 to 120 days Normally, it has the root yield of 12-15 tonnes/ha, and with intensive farming, it can reach 20-25 tons/ha It has high adaptability to various climates Variety KB1 The variety KB1 was selected from open pollination breeding of mother Read derived from America with code: 93-65-629 The young leaves of KB1 are violet while the mature leaves are triangular and green The root has long oblong, white skin, and ivory-white flesh Variety HT2 The variety HT2 was selected from local varieties in Ha Tay, coded: HT2 The young and mature leaves are triangular, serrated; and light green The root has oblong or long eliptic shape, white skin, and highly soft flesh Root yield can reach 20-22 tonnes/ha Variety TM1 The variety TM1 was selected from local varieties in Hai Duong, coded: TM1 The young and mature has heart and serrated shape shaped and light green colour The root has long eliptic shape, pink skin, and white flesh It can reach the root yield of 18-20 tonnes/ha Variety VC01 The variety VC01 was selected from the local varieties in Thai Binh with the code of VC01 The young and mature leaves have heart shape with light green colour and the vines are crawling The root has long eliptic shape, ivory-white skin, and white flesh Root yield can reach 18-20 tonnes/ha Variety VC68-2 The variety VC68-2 was imported from the International Potato Center (Centro Internacional de la Papa-CIP), coded VC68-2 The young and mature leaves are dark green heart and the vines are crawling The root has round shape, violet skin, and ivory-white flesh Its root yield is about 18-20 tonnes/ha Variety VC97-6-3 The variety VC97-6-3 was selected from open pollination breeding of 97-6 The leaves have heart shape; leaves and vines have light green colour, and the vines are crawling The root has round shape, white skin, and ivory-white flesh Root yield of this variety can reach 22-25 tonnes/ha Variety VC04-24: The variety VC04-24 was selected from pollination breeding with code of VC04-24 The leaves and vines are light green and the vines are semi-erect The mature leaves are deeply lobed The root has round shape, yellow flesh with pink spots The yield can reach about 20-22 tonnes/ha 10 Variety VC02-193 The variety VC02-193 was selected from open pollination breeding of KB4 The vine are light green, leaves are dark green The mature leaves are deeply lobed The root has long eliptic shape, white skin, and ivory-white flesh Its yield is about 20-22 tonnes/ha 11 Variety Hoang Long The variety Hoang Long was imported from China in 1969 and is very popular in many places now The yellow vines are crawling The leaves has heart shape, the young foliage has light violet colour The root has pink skin and ivory flesh The yield of roots is high but that of vines and leaves is average Quality of root is also moderate 4.2 Morphological characteristics of 11 studied sweet potato varieties Table showed that varieties have their particular characteristics however most of them are semierect or crawling The colour of the vines and leaves is light green to dark green, except for Hoang Long, which has a violet colour Sweet potato varieties have various leaf shapes such as heart or triangular, deep or shallow lobes, serrates or plain Table 1: Characteristics of 11 studied sweet potato varieties in Project CARD 008/07VIE No Criteria Varieties KL5 No KB1 10 11 HT2 TM1 Vine shape Half standing Half standing Half standing Half standing Half standing Root skin colour Root shape Root flesh colour Deep lobe Red Long Ivory-white Dark green Lobe Violetred Round Green Light green Heart Ivorywhite Round Green Green White Long White Green Green Long White Green Green Long White Dark green Light green Light green Dark green Violet Vine colour Leaf colour Green Green Dark green VC01 Crawling VC68-2 Crawling VC97-6-3 Crawling VC04-24 Half standing Dark green Light green Light green VC02-193 Crawling Green Hoang long Crawling Violet Leaf shape Shallow lobe Serrated heart Heart Pinkred Violetred Ivoryyellow Yellow – spotted violet Heart Violet Round Ivory-white Heart Violetred Round Ivory-white Violet Round Yellow – spotted pink White Long Ivory-white Pink Round Yellow Shallow lobe Deep lobe Heart 4.3 Effects of the climate on sweet potato growth in three provinces of Bac Giang, Thanh Hoa and Quang Tri in 2008-2009 4.3.1 The climate record in Bac Giang Sweet potato origined in a tropical climate Therefore, it grows very well in conditions of relatively high temperature (optimal temperature of 21-23oC) and with 8-10 h/day of sunlight Table 2: Climate record in Bac Giang, 2008 Months Average Rain fall (mm) Relative humidity temperatures (%) (0C) Jan 14.9 4.3 86 Feb 13.5 14.1 78 Mar 20.1 46.5 88 Apr 23.3 86.7 90 May 25.7 97.0 83 Jun 26.1 118.4 84 Jul 27.9 110.0 80 Aug 27.4 145.2 85 Sep 26.2 249.6 87 Oct 29.8 292.6 87 Nov 20.5 237.8 79 Dec 17.3 16.8 76 Source: Center of Weather Forecast in Bac Giang province Sunshine period (h) 77 51 88 90 110 130 180 160 121 176 153 130 The sweet potatoes were planted in Bac Giang on 5-10th October 2008 and harvested on 15th February 2009 The climate data was recorded during the season by the Center of Weather Forecast in Bac Giang province (Tables and 2) - In the first stage of growth, from October until November, the climate was relatively good for the plant to grow As shown in Table 2, the temperatures were 29.8oC and 20.5oC in October and November, respectively - During the stage of root swelling, the temperature decreased suddenly down to very low levels, which influenced negatively nutrient accumulation in root The temperatures were 17.3oC and 14.9oC in December 2008 and January 2009, respectively On the other hand, the sunshine period were too short and continuously decreased from 5.1 h/day, 4.3 h/day to 3.1 h/day in November, December 2008 and January 2009, respectively Table 3: Climate record in Bac Giang, 2009 Months Average Rain fall (mm) Relative humidity temperatures (%) (0C) Jan 14.9 1.4 75 Feb 21.9 13.3 86 Mar 20.5 42.3 84 Apr 22.7 54.3 85 May 24.7 98.5 86 Jun 25.6 120.6 87 Source: Center of Weather Forecast in Bac Giang province Sunshine period (h) 95 55 54 65 80 110 The experiments in Bac Giang were affected by unfavourable climate conditions compared to the normal requirements for temperature of 21-23oC and sunshine period of 8-10 h/day 4.3.2 The climate record in Thanh Hoa In Thanh Hoa, the sweet potatoes were planted on 5-10th October 2008 and harvested on 15th February 2009 The records collected from the Center of Weather Forecast of Thanh Hoa are shown in Tables and - In the first stage of growth in October until November, the weather was relatively good for the sweet potato plant to grow The temperatures were 25.7oC and 21.7oC in October and November, respectively -During the stage of root swelling, the temperature in Thanh Hoa decreased suddenly but were not as low compared to Bac Giang Therefore the climate did not influence too negatively nutrient accumulation by the roots The temperatures were 18.6oC and 16.2oC in December 2008 and January 2009, respectively However, the sunshine period were too short and continuously decreased from 4.3 h/day, 3.5 h/day to 2.5 h/day in Novemver, December 2008 and January 2009, respectively Table 4: Climate record in Thanh Hoa, 2008 Months Jan Feb Mar Apr May Jun Jul Aug Average temperatures (0C) 15.9 13.5 20.1 24.3 26.7 28.1 28.9 28.4 Rain fall (mm) 84.3 15.1 26.5 116.7 97.0 188.4 110.0 145.2 Relative humidity (%) Sunshine period (h) 86 78 88 90 83 84 80 85 77 31 106 110 192 130 185 169 10 Sep 27.2 349.6 Oct 25.7 348.2 Nov 21.7 106.0 Dec 18.6 18.6 Source: Center of Weather Forecast in Thanh Hoa province 87 86 77 78 121 92 129 107 Table 5: Climate record in Thanh Hoa, 2009 Months Average Rain fall (mm) Relative humidity temperatures (%) (0C) Jan 16.2 8.6 78 2eb 22.0 39.2 88 Mar 19.9 35.4 89 Apr 23.6 133.5 90 May 26.0 178.3 87 Jun 27.7 190.5 87 Source: Center of Weather Forecast in Thanh Hoa province Sunshine period (h) 113 105 61 93 162 155 Similar to Bac Giang, the experiments in Thanh Hoa were affected by unavourable climate conditions compared to the optimal temperature of 21-23oC and sunshine period of 8-10 h/day 4.3.3 The climate record in Quang Tri province In Quang Tri, the sweet potatoes were planted on 15-20th December 2008 and harvested on 1520th April 2009 The climate data are shown in Table - At the first stage of growth on 15/December/2008 until January 2009, the relatively low temperature and light influenced negatively on the growth of the sweet potato (Table 6) - At the stage of swelling root, temperature was more stable in February and March about 23.5oC and 24.1oC, respectively The temperature was suitable for root to accumulate the nutrient However, the sunshine period were still very low: about 2.3 h/day, 4.4 h/day to 4.1 h/day in January, February and March 2009, respectively Similar to Bac Giang and Thanh Hoa, the experiments in Quang Tri were affected by inconvenient climate condition compared to the normal requirements for temperature of 21-23oC and sunshine period of 8-10 h/day 11 Table 6: Climate record in Quang Tri, 2009 Months Average Rain fall (mm) Relative humidity temperatures (%) (0C) Jan 18.1 190.0 86 Feb 23.5 15.9 89 Mar 24.1 70.4 93 Apr 25.6 100.5 86 May 27.1 315.0 85 Jun 30.3 13.7 75 Source: Center of Weather Forecast in Quang Tri province Sunshine period (h) 69 132 123 115 210 80 4.4 Evaluate and and select new potato varieties in Bac Giang and Thanh Hoa In Bac Giang and Thanh Hoa, mean weight of roots harvested was determined for all of the new sweet potato varieties were from the winter season 2008 (Table 7) It was showed that the average root weight of KB1 and VC04-24 varieties in different locations were 73.43 and 71.37 g, respectively, which were much higher than those of the other varieties including Hoang Long and the local variety The root weights of the same varieties were significantly different from various locations The average root weights produced from the locations in S1, S2 and S5 were higher than those from S3, S4 and S6 Clearly, besides the varieties, environment conditions (soil, climate) also affected greatly the mean root weights of these sweet potato varieties Table 7: Mean root weight (gram) of sweet potato varieties studied in Winter season 2008 Varieties S1 S2 S3 S4 S5 S6 Average KL5 82.08 70.32 66.50 56.23 82.46 35.67 65.54 KB1 83.53 111.76 64.71 64.81 78.82 36.92 73.43 No 90.65 99.56 36.04 52.10 72.52 42.85 65.62 HT2 83.86 79.73 55.01 43.19 71.16 38.58 61.92 TM1 68.37 83.34 86.75 48.48 68.18 40.42 65.92 VC.01 73.13 85.85 43.53 55.56 77.42 40.55 62.67 VC.68-2 91.97 79.16 43.84 73.76 77.23 43.47 68.24 VC.97-6-3 77.11 47.76 56.95 58.74 68.14 37.44 57.69 VC 04-24 97.90 89.34 42.94 71.72 78.14 48.20 71.37 VC02-193 78.16 92.83 59.28 46.48 77.92 42.40 66.18 Hoang Long 75.29 132.59 38.24 39.72 53.50 40.95 63.38 Local variety 80.85 117.40 51.63 45.99 58.00 43.12 66.17 Average 81.91 90.80 53.79 54.73 71.96 40.88 65.68 LSD (5%) 20.03 44.40 31.31 12.75 10.11 6.07 CV% 14.40 28.90 34.40 13.80 8.30 8.80 Note: S1= Bich Son-Viet Yen, Bac Giang S2= Cao Xa, Tan Yen, Bac Giang S3= Dong Quang, Dong Son, Thanh Hoa S4= Mai Trung, Hiep Hoa, Bac Giang S5= Nguyen Binh, Tinh Gia, Thanh Hoa S6= Quang Minh, Quang Xương, Thanh Hoa 12 The dry matter contents were determined for roots of the sweet potato varieties at all of locations in Bac Giang and Thanh Hoa, 2008 ( Table 8) The highest dry matter content in these sweet potato varieties were 25.65% of HT2 and 25.38% of VC01 The values were much higher than those of Hoang Long (21.29%) and the local (20.49%) On the other hand, in the same varieties, the dry matter content in a location was different between locations For example, HT2 had high dry matter content of 33.5% and 30.73% in S2 and S6, respectively but only 24.6% and 18.57% in S1 and S3, respectively Therefore, varieties and environment caused different dry matter content of these sweet potato roots The main factor was the winter in Bac Giang (S1) and Thanh Hoa (S3) influencing unfavourably dry matter content Table 8: Dry matter content (%) in root of Sweet potato varieties in Winter season 2008 Varieties S1 20.13 18.63 23.37 24.60 22.50 27.53 23.57 24.10 20.33 20.13 21.57 20.23 22.22 3.30 8.80 S2 20.63 26.17 27.87 33.50 23.7 29.10 26.13 20.67 27.20 28.63 24.47 21.73 25.82 3.97 9.10 S3 19.17 19.90 19.50 18.57 19.07 19.13 18.90 18.97 19.33 18.83 18.17 19.20 19.06 1.65 5.10 S4 20.97 21.73 21.23 21.37 20.87 23.0 22.43 22.77 18.87 21.93 22.87 19.83 21.49 1.904 5.2 S5 18.9 19.77 23.83 25.10 18.67 27.13 25.23 20.67 18.20 20.87 21.77 20.73 21.74 2.34 6.40 S6 20.20 23.97 22.47 30.73 18.20 26.40 20.23 20.50 20.90 18.80 18.90 21.23 21.88 3.06 8.20 KL5 KB1 No HT2 TM1 VC.01 VC.68-2 VC.97-6-3 VC 04-24 VC02-193 Hoang Long Local variety Average LSD (5%) CV% Note: S1= Bich Son-Viet Yen, Bac Giang S2= Cao Xa, Tan Yen, Bac Giang S3= Dong Quang, Dong Son, Thanh Hoa S4= Mai Trung, Hiep Hoa, Bac Giang S5= Nguyen Binh, Tinh Gia, Thanh Hoa S6= Quang Minh, Quang Xương, Thanh Hoa Average 20.00 21.70 23.05 25.65 20.50 25.38 22.75 21.28 20.81 21.53 21.29 20.49 22.03 The dry matter content of vine-leaf of vine-leaves as shown in Table 9, varied from 10.62 to 12.22% Most of the varieties had similar values of dry matter content but No8 had the highest average dry matter content of 12.22% The dry matter content of vine-leaves in Bac Giang (S2) and Thanh Hoa (S5) had high values of 11.52 and 12.56%, respectively 13 Table 9: Dry matter content (%) in vine-leaf of sweet potato varieties in Winter season 2008 Varieties S1 S2 S3 S4 S5 S6 Average KL5 11.50 11.14 11.19 9.92 11.70 10.72 11.03 KB1 9.87 11.15 10.83 10.54 11.92 9.41 10.62 No 12.97 12.05 12.13 11.82 13.61 10.733 12.22 HT2 11.75 11.19 12.01 11.42 13.10 11.74 11.87 TM1 10.10 11.51 11.90 11.08 12.56 9.52 11.00 VC.01 10.94 12.21 12.29 11.16 12.99 11.69 11.88 VC.68-2 12.90 8.75 10.28 10.34 11.36 10.74 10.73 VC.97-6-3 10.01 12.84 11.86 10.79 12.12 10.62 11.37 VC 04-24 10.03 12.57 11.33 9.24 11.31 10.10 10.76 VC02-193 9.54 11.31 11.30 11.25 13.23 9.37 11.00 Hoang Long 10.14 12.08 12.08 11.89 13.51 10.64 11.72 Local variety 10.01 11.42 11.54 13.31 13.31 9.88 11.58 Average 10.81 11.52 11.50 11.06 12.56 10.43 11.31 LSD (5%) 1.48 1.90 0.99 1.27 2.32 1.40 CV% 8.10 9.70 5.10 6.80 10.90 7.90 Note: S1= Bich Son-Viet Yen, Bac Giang S2= Cao Xa, Tan Yen, Bac Giang S3= Dong Quang, Dong Son, Thanh Hoa S4= Mai Trung, Hiep Hoa, Bac Giang S5= Nguyen Binh, Tinh Gia, Thanh Hoa S6= Quang Minh, Quang Xương, Thanh Hoa The vine-leaf yields of the new varieties in Bac Giang and Thanh Hoa in the winter season 2008 were calculated and presented in Table 10 - The unfavourable climate in the winter of 2008 affected the growth of the sweet potato varieties (Table 2, 3, and 5) and reduced the vine-leaf yield The highest yield was only 8.01 tonnes/ha from TM1 while Hoang Long and the local variety had very low yields of 5.95 and 6.85 tonnes/ha, respectively - In the same varieties, the vine-leaf yield in various locations were different Therefore, evaluation of adaptability of a variety to the environment is necessary Table 10: Vine-leaf yield (tonnes/ha) of sweet potato in Winter season 2008 Varieties KL5 KB1 No HT2 TM1 VC.01 VC.68-2 VC.97-6-3 VC 04-24 VC02-193 Hoang Long Local variety S1 8.36 7.87 8.71 6.78 8.27 8.33 7.02 7.69 10.64 9.60 6.96 8.38 S2 3.71 3.24 3.91 4.60 4.80 4.60 4.64 11.13 3.64 4.84 3.33 3.62 S3 6.51 4.31 4.96 6.16 6.89 6.18 2.44 4.69 5.40 5.64 3.89 6.49 S4 8.69 8.37 8.60 7.85 9.83 9.03 9.48 8.99 9.06 9.42 7.99 8.09 S5 10.83 10.16 11.23 10.02 13.58 12.10 12.66 11.13 11.45 11.67 10.20 10.88 S6 3.36 3.24 3.71 4.60 4.69 4.40 4.64 3.64 3.42 4.84 3.33 3.62 Average 6.91 6.20 6.85 6.67 8.01 7.44 6.82 7.88 7.27 7.67 5.95 6.85 14 Average 8.22 4.67 5.30 8.78 11.32 3.96 LSD (5%) 1.33 1.52 1.38 0.86 1.21 1.37 CV% 9.50 19.20 15.40 5.80 6.30 20.50 Note: S1= Bich Son-Viet Yen, Bac Giang S2= Cao Xa, Tan Yen, Bac Giang S3= Dong Quang, Dong Son, Thanh Hoa S4= Mai Trung, Hiep Hoa, Bac Giang S5= Nguyen Binh, Tinh Gia, Thanh Hoa S6= Quang Minh, Quang Xương, Thanh Hoa 7.04 Evaluation of root yield of the new sweet potato varieties in Thanh Hoa and Bac Giang is shown in Table 11 In general, all of the root yields were lower than the expected potential yields due to the infavourable weather in all locations However, VC68-2, VC04-24 and VC02-193 achieved higher root yields of 13.75, 14.94 and 13.64 tonnes/ha, respectively, than Hoang Long and the local variety with 10.62 and 10.13 tonnes/ha, respectively The location S1 had the highest root yield of the six locations Table 11: Root yield (tonnes/ha) of sweet potato varieties in Winter 2008 Varieties S1 S2 S3 S4 S5 S6 Average KL5 17.87 10.67 10.29 11.41 11.33 11.16 12.12 KB1 19.36 10.62 12.13 12.12 11.54 11.04 12.80 No 17.78 10.73 10.47 10.61 10.82 11.24 11.94 HT2 15.13 9.38 9.64 10.51 10.54 11.62 11.14 TM1 14.42 12.00 11.22 11.29 11.98 9.42 11.72 VC.01 14.89 10.36 9.73 10.64 8.87 9.04 10.59 VC.68-2 19.29 13.56 13.80 11.88 12.93 11.02 13.75 VC.97-6-3 15.89 13.00 9.93 11.32 10.76 10.27 11.86 VC 04-24 22.62 11.13 12.51 15.16 14.33 13.87 14.94 VC02-193 19.51 12.00 11.78 14.30 13.56 10.69 13.64 Hoang Long 18.40 8.82 7.84 9.93 10.13 8.60 10.62 Local variety 18.73 10.16 7.00 7.68 7.80 9.40 10.13 Average 17.82 11.04 10.53 11.40 11.22 10.62 12.10 LSD (5%) 1.87 1.28 2.68 0.70 0.76 1.83 CV% 6.20 6.90 15.00 3.60 4.00 10.20 Note: S1= Bich Son-Viet Yen, Bac Giang S2= Cao Xa, Tan Yen, Bac Giang S3= Dong Quang, Dong Son, Thanh Hoa S4= Mai Trung, Hiep Hoa, Bac Giang S5= Nguyen Binh, Tinh Gia, Thanh Hoa S6= Quang Minh, Quang Xương, Thanh Hoa In the winter season 2008, the total yields of sweet potato varieties were calculated for all locations in Bac Giang and Thanh Hoa (Table 12) - In general, the new sweet potato varieties had total yields of 17.81-22.21 tonnes/ha, which were higher than the control (Hoang Long) and the local variety 15 - VC68-2, VC04-24 and VC02-193 had total yield of 20.56, 22.21 and 21.31 tonnes/ha, respectively, much higher than Hoang Long (control) and the local varieties with values of 16.57 and 16.9 tonnes/ha, respectively - Among the six locations, the S1 and S5 seemed most suitable for the new sweet potato varietes to grow In the total yield of S1, VC 04-24, VC 02-193 and VC68-2 reached upto 33.27, 29.11 and 26.31 tonnes/ha respectively The highest potential yield of varieties in location is also shown in the Table 12 Table 12: Total yield (tonnes/ha) of sweet potato varieties in all locations in Winter season 2008 Varieties S1 S2 KL5 26.22 14.38 KB1 27.22 13.87 No 26.49 14.64 HT2 21.91 13.98 TM1 22.69 16.80 VC.01 23.22 14.96 VC.68-2 26.31 18.20 VC.97-6-3 23.58 24.13 VC 04-24 33.27 14.78 VC02-193 29.11 16.84 Hoang Long 25.36 12.16 Local variety 27.11 13.78 Mean 26.04 15.71 LSD (5%) 2.25 1.96 CV% 5.10 7.40 Note: S1= Bich Son-Viet Yen, Bac Giang S3= Dong Quang, Dong Son, Thanh Hoa S5= Nguyen Binh, Tinh Gia, Thanh Hoa S3 16.80 16.44 15.42 15.80 18.11 15.91 16.24 14.62 17.91 17.42 11.73 13.49 15.83 2.97 11.10 S4 20.10 20.48 19.21 18.37 21.12 19.66 21.35 20.31 24.22 23.72 17.92 15.76 20.19 1.07 3.10 S5 22.15 21.70 22.05 20.56 25.56 20.97 25.59 21.89 25.79 25.22 20.33 18.68 22.54 1.56 4.10 S6 14.51 14.29 14.96 16.22 14.11 13.44 15.67 13.91 17.29 15.53 11.93 13.02 14.57 2.58 10.50 Average 19.03 19.00 18.80 17.81 19.73 18.03 20.56 19.74 22.21 21.31 16.57 16.97 19.15 S2= Cao Xa, Tan Yen, Bac Giang S4= Mai Trung, Hiep Hoa, Bac Giang 16 ... project of "Selection and development sweet potato varieties with high root quality for food processing in Northern and Central of Vietnam? ??, the objectives are: 1) Select sweet potato varieties for. .. yield - Evaluate and select new potato varieties in Quang Tri based on quality and yield IV RESULTS 4.1 Nature and origin of new sweet potato varieties 4.1.1 Origin of sweet potato selection Variety... purpose of food processing from Food Crops Research Institute with ability to adapt to farming conditions in Northern and Central regions in Vietnam 2) Develop and evaluate some methods of processing