The effects of plant spacing on yield and quality of butterfly pea (Clitoria ternatea L) cultivated in organic-Oriented farming system on grey soil

10 Nong Lam University, Ho Chi Minh City The effects of plant spacing on yield and quality of butterfly pea (Clitoria ternatea L.) cultivated in organic-oriented farming system on grey soil Duong T. T. Pham∗, Tri M. Bui, & Thuy T. H. Tran Faculty of Agronomy, Nong Lam University, Ho Chi Minh City, Vietnam ARTICLE INFO Research Paper Received: March 30, 2020 Revised: May 10, 2020 Accepted: June 02, 2020 Keywords Butterfly pea Clitoria ternatea L. Grey soil Organic-oriented farming system Plant spacing ∗Corresponding author Pham Thi Thuy Duong Email: pttduong@hcmuaf.edu.vn ABSTRACT Clitoria ternatea L. is a plant species that can be used in food and pharmaceutical industry. This study was conducted to evaluate the effects of different plant spacing on the productivity and quality of butterfly pea grown on grey soil in Thu Duc, Ho Chi Minh City. Six treatments correspond to plant spacing of 80 x 15 cm, 80 x 20 cm, 80 x 25 cm, 80 x 30 cm, 80 x 35 cm and 80 x 40 cm. The results showed that the highest flower amount (296.8 flowers/plant) was obtained with butterfly pea planted at the spacing of 80 x 15 cm, commercial flower weight (7.86 g/100 flowers), theoretical yield of fresh flower (1,779.0 kg/1,000 m2), actual yield of fresh flower (841.9 kg/1,000 m2), theoretical yield of commercial flower (194.6 kg/1,000 m2) and actual yield of commercial flower (89.0 kg/1,000 m2). Nevertheless, plant spacings did not affect the dry matter ratio, anthocyanin and tannin content in the commercial butterfly flowers. Cited as: Pham, D. T. T., Bui, T.M., & Tran, T. T. H. (2020). The effects of plant spacing on yield and quality of butterfly pea (Clitoria ternatea L.) cultivated in organic-oriented farming system on grey soil. The Journal of Agriculture and Development 19(3), 10-15. 1. Introduction Clitoria tenatea L. also known as butterfly pea, is a species belonging to Fabaceae family. Cur- rently, the flowers from butterfly pea are being used in food, medicine as well as in cosmetics (Morris, 2009). Especially, the dried butterfly pea flowers can also be used as tea. Butterfly pea tea is characterized by a rich source of natu- ral antioxidants (Kamkaen & Wilkinson, 2009), which is also highly safe (Luu, 2005) and satis- fied most requirements of the consumers. Conse- quently, the flowers are consumed increasingly as healthy food. However, the research on farming techniques which are necessary for butterfly pea reaching high yield and quality, are still limited. Plant spacing is an important determinant of plant growth, development and productivity (Mc- Murray, 2004; McRae et al., 2008; Khaliq et al., 2009). The impact of crop density is mainly due to differences in solar radiation distribution. An optimization of solar radiation uptake is the most important for photosynthetic efficiency. An ap- propriate plant density or spacing helps plants take advantage of sunlight energy, reducing pests and diseases, paving the way for high productiv- ity. In addition, appropriate spacing can also save the seedlings, labor and other costs, those turn out to improve the economic efficiency. Contreras et al. (2012) concluded that when planting but- The Journal of Agriculture and Development 19(3) www.jad.hcmuaf.edu.vn Nong Lam University, Ho Chi Minh City 11 terfly pea plant with a distance of 25 x 25 cm gave highest total grain yield, grain yield per plant, number of pods per plant, number of pods per m2, fruit length, number of seeds in pod as well as the seed weight. However, there is no recom- mendation for suitable plant spacing for butterfly pea flower used as tea. Therefore, the aim of this research was to identify suitable plant spacing for butterfly pea growing on grey soil in organic- oriented farming system. 2. Materials and Methods 2.1. Experimental design The experiment was conducted at the Experi- mental field of Faculty of Agronomy, Nong Lam University, Ho Chi Minh City (September 2019 to January 2020). The seeds of double-winged butterfly pea va- riety (collected in Pham Van Coi Commune, Cu Chi District, Ho Chi Minh City) was sown. Nutrient used for the whole experiment was well composed cow dung, that supplied by the Experimental field of Animal Science and Veteri- nary Medicine Faculty, Nong Lam University in Ho Chi Minh city. The manure was applied at a rate of 5.0 tons/ha at 15 days before planting. Insects and butterflies occurrences on the ex- perimental field were cached manually. No other chemical fertilizers or pesticides was used before and during cultivation period. One-factor experiment was arranged in a Ran- domized Completed Block Design (RCBD) in- cluded 6 treatments with 3 replicates. The plant spacing in the experiment included: 80 x 15 cm (8,333 plants/1,000 m2), 80 x 20 cm (6,125 plants/1,000 m2), 80 x 25 cm (The control) (5,000 plants/1,000 m2), 80 x 30 cm (4,167 plants/1,000 m2), 80 x 35 cm (3,571 plants/1,000 m2) and 80 x 40 cm (3,125 plants/1,000 m2). Total number of experimental plots was 18 plots; a single plot area was 16.8 m2; The spacing between two neigh- bouring plots was 0.5 m; The whole experimental area was 302.4 m2. 2.2. Land preparation and field management Beds were established with a size of 6.0 x 2.8 m, each bed consisted of 3 single rows, each bed was 80 cm apart and 20 cm from the aisle; Composted cow dung was applied at the rate of 5 tons/ha 15 days before planting. Staking setup: U-shaped staking was made of bamboo, with a height of 1.5 m, each row con- sisted of 7 bamboo poles separated by 1.0 m; a black film was used to cover along the rows for weed preventing. Seeds were sown on a nursery. After 15 days, the seedlings reached 3 pairs of leaves which then were transplanted onto the experimental field. At 60 days after planting, the plant tips were cut off for branch boosting. Experimental field was watered once/day. Weed control was conducted manually once in every 15 days. When butterfly pea at flowering stage, new opening flowers were harvested every 2 days. The fresh flowers were left on open air in 48 hours for naturally dryness, then finally, dried at 95oC for 40 minutes (Luong, 2004). 2.3. Data collection and statistics Data from following parameters were collected, including: Total numbers of flowers per plant (flow- ers/plant): Count the average number of flowers on the target plants at all harvests until the end of the experiment; Fresh flowers weight (g/100 flow- ers): Weigh 100 fresh flowers at harvest time 60, 75 and 90 days after planting, then average; Com- mercial flower weight (g/100 flowers): Weigh 100 dried flowers at harvest time 60, 75 and 90 days after planting, after drying at 95oC for 40 minutes and then average; Theoretical fresh flower yield (kg/1,000 m2): [Total number of flowers/plant (flower/plant) * fresh flower weight (g/100 flow- ers) * number of plants/1,000 m2]/105; Actual fresh flower yield (kg/1,000 m2): [Total fresh flow- ers weight/plot (kg) x 1,000]/16,8; Theoretical commercial flower yield (kg/1,000 m2): [Total number of flowers/plant (flower/plant) * com- mercial flower weight (g/100 flowers) * number of plants/1,000 m2]/105; Actual commercial flower yield (kg/1,000 m2): [Total commercial flowers weight/plot (kg) x 1,000]/16,8. Anthocyanin content in commercial flowers was determined using the method TCVN 11028:2015; Tannin content was determined by Leventhal method. Data analysis was conducted with ANOVA test and Duncan rank at significance level α = 0.01 using SAS 9.1 software. www.jad.hcmuaf.edu.vn The Journal of Agriculture and Development 19(3) 12 Nong Lam University, Ho Chi Minh City Table 1. Soil characters of the experimental plots1 Indices Unit Result Method pHKCl(1:5) 5.501 pH meter EC(1:5) mS/cm 0.367 EC meter Total Organic Car- bon % 0.718 Tiurin Total N % 0.062 Kjeldahl N-NH+4 mg/100 g 0.597 Devardar – Alloy C/N 11.581 Total P2O5 % 0.053 Colorimeter Availability P2O5 mg/100 g 4.390 Bray #1 Total K2O % 0.154 Flame photometer Exchangeability K2O mg/100 g 5.085 Flame photometer CEC meq/100 g 7.801 Acetate Amonium Soil texture % Sand: 82.20 Loam: 13.05 Clay: 4.75 Densitometrer 1Analyzed by Department of Soil Science, Faculty of Agronomy, Nong Lam University, 2019. Table 2. Amount and mass of butterfly pea flower under the influence of plant spacings Plant spacing (cm) Flower amount(flowers/plant) Fresh flower weight (g/100 flowers) Commercial flower weight (g/100 flowers) 80 x 15 296.80a 73.23ab 7.86a 80 x 20 290.70a 73.98a 7.88a 80 x 25 (Control) 277.23a 72.95ab 7.92a 80 x 30 249.20b 70.20b 7.22b 80 x 35 204.50c 70.18b 7.33b 80 x 40 180.00c 69.95b 7.46b CV (%) 4.27 1.67 1.48 F value 60.93** 6.95** 22.77** a-cIn the same column, numbers with the same character are statistically insignificant difference. **: the difference is statistically significant at α = 0.01. 3. Results and Discussions 3.1. Evaluation of soil quality at the experi- mental field Physical and chemical analysis results of the experimental soil (Table 1) suggested that the ex- periment plot soil has texture containing 82.20% of sand, 13.05% of loam and 4.75% of clay. Ac- cording to Garc´ıa-Gaines & Frankenstein (2015) the soil at the experimental field is belonging to loamy sand texture. The soil was highly acidic (pHKCl(1:5) = 5.501) and not saline (EC(1:5) = 0.367 mS/cm) (Slavich & Petterson, 1993). It was recommended that the soil pH ranged from 5.5 to 8.9, which was acceptable for butterfly pea (Singh et al., 2017). The soil organic C content was low (0.718%) and the C/N ratio was 11.581. The soil had low levels of macronutrients (Rayment & Lyons, 2011). Furthermore, cation exchange capability was also low. However, butterfly pea is a native plant, it is highly adaptable to various soil types therefore this location was acceptable for butter- fly pea cultivation. Even those, organic fertilizer supplement is necessary to provide nutrients for plants during cultivation. 3.2. Influence of plant spacing to amount and mass of butterfly pea flower The number of flowers and flower weight are most important factor correlating to butterfly pea flower yield. At the same plant spacing, the The Journal of Agriculture and Development 19(3) www.jad.hcmuaf.edu.vn Nong Lam University, Ho Chi Minh City 13 Table 3. Theoretical and actual yields of butterfly pea under the influence of plant spacing Plant spacing (cm) Theoretical fresh flower yield(kg/1000 m2) Actual fresh flower yield (kg/1000 m2) 80 x 15 1,812.6a 841.9a 80 x 20 1,345.5b 721.9b 80 x 25 (Control) 1,011.0c 562.2c 80 x 30 728.5d 511.0c 80 x 35 511.8e 442.3cd 80 x 40 395.0e 371.6d CV (%) 6.3 7.7 F value 233.9** 47.3** a-eIn the same column, numbers with the same character are statistically insignificant difference. **: the difference is statistically significant at α = 0.01. greater the number of flowers and the heavier weight, the higher the yield will be. Results pre- sented in Table 2 showed that the total number of flowers per plant was significantly different be- tween plants grown at different spacing in the ex- periment. Planting at the spacing of 80 x 15 cm gave the most flowers (296.8 flowers/plant), but not statistically different from the plant spacing of 80 x 20 cm (290,70 flowers/plant) and 80 x 15 cm (277.23 flowers/plant). Planting at the spac- ing of 80 x 40 cm obtained lowest number of flow- ers (only 180 flowers/plant), the difference was 116.80 flowers/plant lower as compared to plant- ing at the spacing of 80 x 15 cm. Fresh flower weight and commercial flower weight of butterfly pea plants were significantly different under the influence of different plant spacing. Butterfly pea plants grown at a spac- ing of 80 x 20 cm gained the highest fresh flower weight (73.98 g/100 flowers), event it was not sta- tistically different from planting at the spacing of 80 x 15 cm or 80 x 25 cm. The lowest fresh flowers weight gained when planting at the spacing of 80 x 40 cm (69.95 g/100 flowers). It was 4.03 grams lower than when planting at the spacing of 80 x 15 cm. Similarly, the highest commercial flower weight of butterfly pea was obtained when planting at the spacing of 80 x 20 cm (7.88 g/100 flowers) even it was not statistically different from plant- ing at the spacing of 80 x 15 cm or 80 x 25 cm. Planting at the spacing of 80 x 40 cm gained low- est commercial flower weight (7.46 g/100 flow- ers) but which was not statistically different from planting at the spacing of 80 x 30 or 80 x 35 cm; It was only 0.42 g lower if compared to planting at spacing of 80 x 15 cm. Because the experiment conducted at the end of rainy season, most of growth season was during dry and hot weather, plant population at higher density perhaps made microclimate not as hot as in lower density population. The result shown that at higher plant spacing (80 x 15 cm, 80 x 20 cm, 80 x 25 cm), butterfly pea plants grown bet- ter, giving more flowers and higher flower mass. This result were in accordance with a report by Tran & Pham (2018) on Limnophila rugosa (Roth) Merr. when they found that growing in a long spacing, especially when the growing sub- strate covered so it is less affected. Because of high temperature at the experimental area, the plants grew well and formed more leaves. 3.3. Influence of plant spacing to theoretical and actual yields of butterfly pea Results presented in Table 3 shown that but- terfly pea grown at the spacing of 80 x 15 cm reached highest theoretical yield as well as actual flower yield (1,812.6 and 841.9 kg/1,000 m2, re- spectively). The actual yield of fresh flowers ac- counts for 46.4% of the theoretical fresh flower yield. Besides, butterfly pea grown at the spac- ing of 80 x 40 cm, yielding the lowest theoretical and actual fresh flower yields (395.0 and 371.6 kg/1,000 m2, respectively). The actual yield of fresh flowers accounts for 94.1% of the theoreti- cal fresh flower productivity. The difference in the ratio of actual yield and theoretical yield was due to the level of coverage of the pea plants. When the pea plants were higher density, it might lead to the plants being overlapped. In fact, plants at high density tended to be overlapped each other, which affected to actual numbers of harvestable flowers on the plot. As a consequence, there was a big difference between the theoretical fresh yield www.jad.hcmuaf.edu.vn The Journal of Agriculture and Development 19(3) 14 Nong Lam University, Ho Chi Minh City Table 4. Commercial flower yields of butterfly pea under the influence of plant spacings Plant spacing (cm) Theoretical commercial floweryield (kg/1000 m2) Actual commercial flower yield (kg/1000 m2) 80 x 15 194.6a 89.0a 80 x 20 143.4b 75.9b 80 x 25 (Control) 109.8c 60.1c 80 x 30 75.0d 52.5cd 80 x 35 53.6e 45.7de 80 x 40 42.0e 39.0e CV (%) 5.7 7.3 F value 296.6** 55.2** a-eIn the same column, numbers with the same character are statistically insignificant difference. **: the difference is statistically significant at α = 0.01. Table 5. Dry matter, anthocyanin and tannin contents of butterfly pea flowers under influence of plant spacings Plant spacing (cm) Contents (%)Dry matter Anthocyanin Tannin 80 x 15 10.753 0.538 1.817 80 x 20 10.661 0.546 1.824 80 x 25 (control) 10.856 0.538 1.820 80 x 30 10.295 0.540 1.824 80 x 35 10.490 0.540 1.827 80 x 40 10.635 0.536 1.829 CV (%) 1.930 1.745 0.483 F value 2.831ns 0.380ns 0.760ns ns: non-significant. and the actual yield. Less shading between plants reduced the difference. 3.4. Influence of plant spacing to commercial flower yields of butterfly pea Commercial flower ratio is a determinant of economic efficiency for the farmers. In this re- search, butterfly pea flowers were naturally dried for 48 hours at room temperature then trans- ferred to temperature of 95oC for 40 min in order to reach commercial quality level with moisture content was about 12%. The results presented in Table 4 shown that the difference of theoretical and actual commercial flower yield was statistical significance between flower collected from plants grown in different spacing. Butterfly pea plants grown at the spacing of 80 x 15 cm obtained the highest theoretical commercial yield (194.6 kg/1000 m2); the plants grown at the spacing of 80 x 40 cm (42.0 kg/1000 m2), was 152.6 kg/1000 m2 lower than that. The actual harvest of commercial flowers was also highest with the butterfly pea planted at the spacing of 80 x 15 (reaching 89.0 kg/1,000 m2). It was statistically significant higher as compared to plants in all other treatments. Plant grown at the spacing of 80 x 40 cm, showed the lowest commercial flower (39.0 kg/1,000 m2); it was 40 kg/1,000 m2 lower as compared to plants grown at the spacing 80 x 15 cm. In general, it was obvious that the plant density greatly affected to both theoretical and commer- cial flower yields. The butterfly pea when grown at a higher density obtained a higher yield. At the same time, the difference between theoretical yield and actual yield was high. 3.5. Influence of plant spacing to dry matter, anthocyanin and tannin contents of but- terfly pea flowers Results in Table 5 indicated that different plant spacing did not affect the quality of butterfly pea flower indices including dry matter ratio, an- thocyanin and tannin content in dried flowers. The dry matter ratio of the butterfly pea flower ranged from 10.3 to 10.86%. In the commercial The Journal of Agriculture and Development 19(3) www.jad.hcmuaf.edu.vn Nong Lam University, Ho Chi Minh City 15 flowers, anthocyanin content ranged from 0.54 to 0.55%. This result suggested that anthocyanin in butterfly pea flowers is higher than that in some fruits such as blueberries (0.08 to 0.53%), cherry (0.35 to 0.45%), black raspberry (0.08 to 0.18%) (Horovitz et al., 2008). Anthocyanin re- lated to the intensity of plant colour, the darker the colour, the higher the anthocyanin content. Nevertheless, tannin content in commercial but- terfly peas ranged from 1.82 to 1.83%, is much lower than that in black tea (13.36%), green tea (2.65%) and Oolong tea (8.66%) (Khasnabis et al., 2015). Tannin is polyphenol compounds in plants that help to against bacteria and induce acrid taste, it plays an important role in the qual- ity of tea products. 4. Conclusions Pea flower of plants grown at the spacing of 80 x 15 cm gained highest number of flowers on plant (296.8 flowers/tree), dry flower weight (7.86 g/100 flowers), the theoretical fresh flower yield (1,779.0 kg/1,000 m2), the actual fresh flower yield (841.9 kg/1,000 m2), the theoretical com- mercial flower yield (194.6 kg/1,000 m2) as well as the actual commercial flower yield (89.0 kg/1,000 m2). The different plant spacing did not affect quality criteria such as dry matter, anthocyanin and tannin content in commercial butterfly pea flower. References Contreras, C. I .M, Torres, B. M. J., Herna´ndez, M. A. S., & Lo´pez, M. L. P (2012). Evaluation of plant spac- ing on seed yield and quality of Clitoria ternatea L. cv. Tehuana. Tropical and Subtropical Agroecosystems 15(3), 489-497. Garc´ıa-Gaines, R. A., & Frankenstein, S. (2015). USCS and the USDA soil classification system. Missouri, USA: Engineer Research and Development Center, US Army Crops of Engineer. 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