University, Nakhon Pathom, Thailand, 73140 Adding Efficiency cassava production by irrigation in Coarse-loamy, mixed, Oxic Paleustults soil. K. Panitnok(1), S. Chaisri(2), E. Sarobol(3), N. Udomprasert(7), S. Ngamprasitthi(4), P. Chaisri(2), P. Changlek(5) and P. Thongluang(6) (1)Khao Hin Son Research Station, Kasetsart University, Chachoengsao, Thailand, 24120 (2)Lop Buri Research Station, Kasetsart University, Lop-Buri, Thailand, 15250 (3)Department of Agronomy, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand, 10900 (4)Suwanwajokkasikit Field Crops Research Station, Kasetsart University, Nakhon Ratchasima, Thailand, 30320 (5)Agro-Ecological System Research and Development Institute, Kasetsart University, Phetchabun, Thailand, 67270 (6)National Corn and Sorghum Research Center, Kasetsart University, Nakhon Ratchasima, Thailand, 30320 (7)Department of Agronomy, Faculty of Agriculture Kamphaeng Saen, Kasetsart University, Nakhon Pathom, Thailand, 73140 Corresponding author E-mail: kingkan_mee@hotmail.com Abstract Results Table 1. Yield and yield components of three cassava cultivars in 5 water regimes; T1= application at the rate of 60 mm per plant per month at 2 to10 months after planting, T2= application at the rate of 60 mm per plant per month at 2 to 4 months after planting, T3= application at the rate of 60 mm per plant per month at 5 to 7 months after planting, T4= application at the rate of 60 mm per plant per month at 8 to10 months after planting and T5= application by rain in November 2010-October 2011 at Khao Hin Son Research Station, Chachoengsao, Thailand. The increase in production of crop plants has been slowed by the occurrence of environmental stresses. The significant one is drought. Then the objective of this study was to determine the effect of irrigation on yield of three cassava cultivars grown on Map Bon, coarse-loamy variant soil at Khao Hin Son Research Station, Chachoengsao, Thailand during November 2010 to October 2011. The experiment was carried out in a split plot in Randomized Complete Block Design (RCBD) with three replications. Five irrigation schemes were the main plot: (1) application at the rate of 60 mm per plant per month at 2 to10 months after planting, (2) application at the rate of 60 mm per plant per month at 2 to 4 months after planting, (3) application at the rate of 60 mm per plant per month at 5 to 7 months after planting, (4) application at the rate of 60 mm per plant per month at 8 to 10 months after planting, and (5) application by rain. The sub plot comprised of three cassava cultivars; i.e. KU 50, HB 60 and HB 80. The results illustrated that the treatments with various period of irrigation schemes gave differences in fresh stem weight, fresh leaves weight and fresh root yield but the treatments with application at the rate of 60 mm per plant per month at 8 to 10 months after planting tended to give higher fresh stem weight, fresh leaves weight and fresh root yield by 93, 21 and 13% (37.57, 11.81 and 69.24 ton per hectare) and KU 50 tended to give higher fresh root yield than HB 60 and HB 80 by 68.10, 59.73 and 57.11 ton per hectare, respectively. The application at the rate of 60 mm per plant per month at 2 to 4, 5 to 7 and 8 to 10 months after planting tended to give higher root starch content and HB 80 tended to give higher root starch content (26.47%). Varieties Treatment Fresh stem weight Ton/ha Fresh leaves Fresh root yield Fresh lower stem weight Root starch content % Root number 1000 root per ha KU 50 T1 21.95 b 7.41 ab 66.39 a 9.94 b 25.90 a 116.91 b T2 26.04 b 8.68 ab 57.99 a 12.15 b 26.40 a 134.72 ab T3 24.65 b 5.90 b 66.32 a 10.42 b 25.17 a 150.35 ab T4 37.57 a 11.81 a 84.88 a 17.86 a 183.78 a T5 19.45 b 9.72 ab 64.93 a 11.81 b 25.40 a 109.72 ab HB 60 19.19 a 11.72 a 50.92 a 9.83 a 22.30 b 133.10 ab 21.88 a 10.76 a 57.64 a 9.37 a 24.63 ab 118.75 ab 17.16 a 7.55 a 68.36 a 9.45 a 25.70 a 135.76 ab 17.94 a 9.73 a 62.36 a 8.97 a 25.57 a 145.02 a 17.36 a 10.42 a 59.38 a 10.07 a 25.97 a 90.63 b HB 80 23.67 a 11.05 a 61.50 a 7.12 a 26.03 ab 173.77 a 31.94 a 43.75 a 8.33 a 25.73 ab 131.25 a 26.04 a 9.03 a 60.42 a 6.94 a 26.40 ab 170.14 a 26.17 a 11.93 a 60.48 a 10.29 a 28.83 a 149.81 a 27.43 a 59.37 a 25.37 b 122.57 a Mean of treatment 21.61 a 9.88 a 59.60 ab 8.96 a 24.74 a 141.26 a 26.62 a 9.95 a 53.13 b 25.59 a 128.24 a 22.62 a 7.49 a 65.03 ab 8.94 a 25.76 a 152.08 a 27.23 a 11.16 a 69.24 a 12.37 a 26.52 a 159.54 a 21.41 a 10.65 a 61.23 ab 25.58 a 107.64 a ** * Mean of varieties 25.93 ab 8.71 a 68.10 a 12.44 a 25.61 a 139.10 a 18.71 b 9.93 a 59.73 a 9.54 a 24.83 a 124.65 a 27.05 a 10.85 a 57.11 a 8.55 a 26.47 a 149.51 a Table 2. Soil moisture of Map Bon, coarse-loamy variant in 5 water regimes; T1= application at the rate of 60 mm per plant per month at 2 to10 months after planting, T2= application at the rate of 60 mm per plant per month at 2 to 4 months after planting, T3= application at the rate of 60 mm per plant per month at 5 to 7 months after planting, T4= application at the rate of 60 mm per plant per month at 8 to10 months after planting and T5= application by rain in November 2010-October 2011 at Khao Hin Son Research Station, Chachoengsao, Thailand. (g/g). Varieties Treatment Planting Date 60 days after planting 84 days 151 days 188 days 211 days KU 50 T1 0.06283 b 0.04540 ab 0.08263 a 0.06460 bc 0.08200 a 0.04863 bc T2 0.07867 ab 0.03530 b 0.07837 a 0.05860 bc 0.02783 c 0.02600 c T3 0.08673 ab 0.03533 b 0.08093 a 0.05923 bc 0.04640 bc 0.06753 ab T4 0.11790 a 0.03833 ab 0.07110 a 0.07387 abc 0.02633 c 0.02653 c T5 0.07773 ab 0.06160 a 0.09240 a 0.07920 abc 0.02913 c 0.02667 c HB 60 0.10657 ab 0.03573 b 0.07150 a 0.06983 abc 0.06987 ab 0.07493 a 0.10817 ab 0.05207 ab 0.09033 a 0.06863 abc 0.03767 c 0.02657 c 0.08873 ab 0.03403 b 0.09797 a 0.08820 ab 0.05510 abc 0.05610 ab 0.11110 ab 0.04483 ab 0.09517 a 0.04133 c 0.03950 c 0.02567 c 0.09827 ab 0.03890 ab 0.08357 a 0.06740 abc 0.02630 c 0.03007 c HB 80 0.09673 ab 0.04210 ab 0.09893 a 0.06827 abc 0.07020 ab 0.05667 ab 0.09167 ab 0.02970 b 0.07330 a 0.05713 bc 0.04770 bc 0.02583 c 0.08137 ab 0.03417 b 0.10917 a 0.06423 bc 0.05053 bc 0.06087 ab 0.10930 ab 0.04663 ab 0.06947 a 0.06567 abc 0.03573 c 0.03717 c 0.10660 ab 0.04177 ab 0.07730 a 0.10690 a 0.04757 bc 0.02917 c Mean of treatment 0.08871 a 0.04108 a 0.08436 a 0.06757 a 0.07402 a 0.06008 a 0.09283 a 0.03902 a 0.08067 a 0.06146 a 0.03773 a 0.02613 b 0.08561 a 0.03451 a 0.09602 a 0.07056 a 0.05068 a 0.06150 a 0.11277 a 0.04327 a 0.07858 a 0.06029 a 0.03386 a 0.02979 ab 0.09420 a 0.04742 a 0.08442 a 0.08450 a 0.03433 a 0.02863 ab * ns Mean of varieties 0.08477 a 0.04320 a 0.08109 a 0.06710 a 0.04234 a 0.03907 a 0.10257 a 0.04112 a 0.08771 a 0.06708 a 0.04569 a 0.04267 a 0.09713 a 0.03887 a 0.08563 a 0.07244 a 0.05035 a 0.04194 a Introduction Cassava is one of the important economic crops of North-Eastern and Eastern parts of Thailand. In 2009, the fresh cassava production is about 28,000,000- 30,000,000 tons per year, the revenue earned by exported cassava and cassava products are about fifty-thousands of millons of baht per year.Furthermore, cassava products is applicable to many industries including food, paper, adhesive and more, 500,000 families, cassava products aims to support the cassava-growing farmers’ income. Average cassava yield was very low (2,479 kg rai -1) due to low soil fertility resulted from long term, continuous cultivation of cassava without simultaneously improving soil fertility or soil and water conservation perspective. The Map-Bon, coarse-loamy variant is in the coarse-loamy, mixed, Oxic Paleustults great group soil. The important characteristics of this top soil (0-7/10 and 7/10-32 cm)are : neutral to medium acid soil, sandy loam; weak fine and medium subangular blocky structure; very friable-friable, non sticky, non plastic; many fine- many fine tubular and many medium interstitial pores; and few fine-medium roots; granite and quartzite derived soil parent material; well drainage; moderate permeability; medium run off and surface soil erosion. Materials and Methods Experimental site The Field experiment was located at Chachoengsao province (13ํ 10่ - 13ํ 59่ N latitude ; 100ํ 50่ – 102ํ 1่ E longtitude) and the experiment was carried out from November 2010 to October 2011 at the Khao Hin Son Research Station of Kasetsart University, Phanomsarakam, Chachoengsao, Thailand. The soil texture was loamy sand with pH of 4.37 – 5.00 (very strongly acid-extremely acid) Methods The experiment was laid out as a split plot in RCBD design with three replications. Size of sub plot was 5x7 m.The main plot treatments were : T1) application at the rate of 60 mm per plant per month at 2 to10 months after planting, T2) application at the rate of 60 mm per plant per month at 2 to 4 months after planting, T3) application at the rate of 60 mm per plant per month at 5 to 7 months after planting, T4) application at the rate of 60 mm per plant per month at 8 to10 months after planting and T5) application by rain, and 3 cultivars subplots consist of, V1) KU 50, V2) HB 60 and V3) HB 80. Weed was controlled twice with planting date and one month after planting by herbicide and hand tool. Application of 15-15-15 chemical fertilizer at the rate of 50 kg per 312.5 per hectare at two months after planting. Acknowledges This project was financially supported by Kasetsart University Research and Development Institute (KURDI). Conclusion ใ In the cultivar, HB 80 and KU 50 gave the highest fresh stem weight, KU 50 tended to give higher fresh root yield, while HB 80 tended to give higher root number per plant and root starch content. In the irrigation treatment, T4) application at the rate of 60 mm per plant per month at 8 to10 months after planting tended to give the highest fresh stem, leaves and lower stem weight, root starch content, root number and all so gave the highest fresh root yield. In the cultivar and irrigation treatment, KU 50 with application at the rate of 60 mm per plant per month at 8 to10 months after planting (T4) tended to give the highest fresh root yield, while HB 80 with application at the rate of 60 mm per plant per month at 8 to10 months after planting (T4) tended to give the highest root starch content.