Rice production in Cambodia / edited by H. J. Nesbitt - IRRI books

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ladesh. Since the earliest flowering time targeted for photoperiod-sensitive varieties in Cambodia is October, very few materials from the strong breeding programs of India and Bangladesh are useful. In view of this, CIAP has embarked on the development of photoperiod-sensitive varieties to meet the country’s future needs. IRRI supports CIAP by providing segregating populations derived from crosses between Cambodian varieties and improved varieties. Selection environments. The environment under which selection is conducted indicates the environment in which a selected variety will perform well. Cognizant of the limited resources of the farmers, the low fertility of most Cambodian soils, and the risks associated with rainfed lowland rice culture, the present yield trials are conducted using a low level of fertilizer (20 kg N, 4.4 kg P 8.3 kg K ha -1 ). In some research sites, supplementary irrigation is being done; in others, rainfall is a critical factor and the crop is often exposed to drought, flash flood, and submergence. On-farm variety adaptation trial. In each maturity group, released varieties and/or outstanding selections in multilocation on-station trials are channeled into the on-farm adaptation trials (OFATs) (Makara et al 1995). This nonreplicated trial is conducted by farmers in their farms using their own resources and management practices and their best variety as check.. Each variety is grown in a 100-m 2 plot. Farmers keep the harvest. In OFATs, farmers are given the opportunity to select the variety(ies) suited to their individual management methods and needs. OFATs also serve as a demonstration area to attract neighboring farmers. It is a major venue by which new varieties are disseminated. As a seed source, OFATs have an important role to play since Cambodia has no seed industry to speak of. Through OFATs, researchers become aware of the farmers’ varietal requirements. Varietal releases A total of 16 varieties identified in the CIAP testing program have been approved by the Varietal Recommendations Committee (VRC) of Cambodia for rainfed lowland ecosystems since 1990 (Table 5.4). There are four early-duration varieties which are also suited to dry season rice cultivation. Modern medium-duration varieties. Santepheap ( santepheap means peace in Khmer) 1, Santepheap 2, and Santepheap 3 are modern medium-duration varieties. The first two are photoperiod-insensitive and were developed by IRRI. Santepheap 3 is a weakly sensitive variety developed at the Orissa University of Agriculture and Technology in India. They mature in less than 140 d and have intermediate plant stature (Table 5.5). The average yields in advanced yield trials fertilized with 60 kg N, 13.2 kg P, and 24.9 kg K ha -1 were 3.9 t ha -1 for Santepheap 1 and 4.0 t ha -1 for Santepheap 2 and Santepheap 3. They have at least a 14 % yield advantage over check variety IR42. In 280 on-farm variety trials conducted from 1992 to 1995, the three varieties had higher mean yields than the farmers’ best varieties. Santepheap 3 had a 16% yield advantage; Santepheap 2, 8.3 %; and Santepheap 1, 4.2 %. In OFATs, farmers generally apply low levels of fertilizer. Farmers were asked to identify their first and second preferences among varieties tested. Some farmers identified two first preferences and two second preferences. Santepheap 3 was the most preferred variety, being ranked first by 130 farmers. Santepheap 1 and Santepheap 2 were ranked first by 64 and 68 farmers, respectively. Local checks were given first preference by 16 farmers. All recommended varieties had a higher second preference score than the check. The differential preference suggests that different varieties could find their own niche in farmers’ fields. RICE ECOSYSTEMS AND VARIETIES 51
Table 5.4 Recommended varieties sponsored by CIAP for the rainfed lowland rice ecosystem of Cambodia. Variety Designation Origin Year released Early duration a IR66 IR72 Kru Kesar Medium duration Santepheap 1 Santepheap 2 Santepheap 3 CAR 1 CAR 2 CAR 3 Late duration CAR 4 CAR 5 CAR 6 CAR 7 CAR 8 CAR 9 lR32307-107-3-2-2 lR35366-40-3-3-2-2 lR13429-150-3-2-1-2 lR48525-100-1-2 lR43342-10-1-1-3-3 lR45411-40-2-1 OR142-99 Pram Bei Kuor (PPD679) Sambak Kraham (PPD597) Sraem Choab Chan (Germplasm B-293) Changkom Ropeak (Germplasm B-528) Kantouy Touk (PPD156) Sae Nang (Germplasm B-429) Changkong Kreal (PPD 723) Phcar Sla (PPD 364) Srau Kol (PPD 86) IRRI, Philippines IRRI, Philippines IRRI, Philippines IRRI, Philippines IRRI, Philippines IRRI, Philippines OUAT, India Cambodia Cambodia Cambodia Cambodia Cambodia Cambodia Cambodia Cambodia Cambodia 1990 1990 1990 1993 1992 1992 1992 1995 1995 1995 1995 1995 1995 1996 1996 1996 a Also recommended for the dry season. Table 5.5 Agronomic characteristics of recommended modern medium-duration varieties. Station trials Yield in on-farm trials (t ha -1 ) a Variety Duration Height Yield % YA b 1992 1993 1994 1995 Mean % YA (d) (cm) (t ha-I) Santepheap 1 133 106 3.9 14.7 2.7 (87) 2.3 (56) 2.4 (76) 2.5 (58) 2.5 (277) 4.2 Santepheap 2 136 108 4.0 14.3 2.9 (87) 2.4 (57) 2.4 (76) 2.6 (58) 2.6 (278) 8.3 Santepheap 3 138 106 4.0 17.6 3.1 (87) 2.5 (57) 2.5 (77) 2.8 (58) 2.8 (279) 16.7 Check c - - 3.4/3.5 d - 2.5 (87) 2.3 (55) 2.2 (74) 2.5 (58) 2.4 (274) - a Values in parentheses refer to number of trials conducted. b YA is the yield advantage of the recommended variety over the check. c Check variety for station trials was IR42 while that for on-farm trials was the farmer's best variety. Check variety differs from site to site. d First value to be used when comparing Santepheap 1 and 3 with the check; second value for comparing Santepheap 2 with the check. Santepheap 3 appears to have a wider adaptation than Santepheap 1 and Santepheap 2. For example, in the 1995 OFATs, eight farmers reported a period of drought. The mean yield of Santepheap 3 was 2.3 t ha -1 while that of farmers’ varieties was 2.2 t ha -1 . Santepheap 1 had 1.9 t ha -1 , while Santepheap 2 had 2.0 t ha -1 . Another example involved the trials conducted in Pursat Province in 1994. The Pursat Agronomy Office in collaboration with UNDP conducted OFATs in 59 sites while CIAP conducted theirs in 11 sites. In the CIAP trials, the farmers applied their own cultural management practices which often involved low fertilizer levels. In the Pursat- 52 JAVIER
Page 2 and 3:
EDITED BY H. J. NESBITT Cambodia-IR
Page 4:
Foreword Rice production in Cambodi
Page 8 and 9: CHAPTER 1 Rice in the Cambodian eco
Page 10 and 11: tions. Because of the importance of
Page 12 and 13: It was under this nationalized syst
Page 14 and 15: workers according to the amount of
Page 16 and 17: Table 1.2 Rice and other crop areas
Page 18 and 19: 1994). Average farm sizes vary acro
Page 20 and 21: Cited references Bolton M. 1996. Re
Page 22 and 23: CHAPTER 2 Topography, climate, and
Page 24 and 25: Temperature At the peak of the hot
Page 26: improving its exposure to solar rad
Page 29 and 30: Geomorphology Cambodia’s rice-gro
Page 31 and 32: throughout the profile and, in some
Page 33 and 34: Kompong Siem soil. The Kompong Siem
Page 35 and 36: Table 3.4 Proportion (%) of each ri
Page 38 and 39: CHAPTER 4 Rice-based farming system
Page 40 and 41: flowering date. Early-maturing vari
Page 42 and 43: Double cropping of rice with cash c
Page 44: Cattle and water buffalo provide dr
Page 47 and 48: Table 5.1 Different rice ecosystems
Page 49 and 50: Table 5.2 Area planted to rice ('00
Page 51 and 52: Seeding rate varies from 50 to 120
Page 53 and 54: Excessive rains from September to O
Page 55 and 56: Table 5.3 Mean and range (in parent
Page 57: the country where the improved vari
Page 61: Table 5.6 Performance of recommende
Page 71 and 72: season deepwater rice areas that ha
Page 73 and 74: Table 5.7 Yield, growth duration, a
Page 75 and 76: varieties. However, it is very like
Page 77 and 78: have good elongation ability. Durin
Page 79 and 80: Figure 5.4 shows the flooding patte
Page 81 and 82: Pests. Insect pests and diseases ar
Page 83 and 84: to upland rice could be found in ot
Page 85 and 86: Uprooted seedlings are covered with
Page 87 and 88: CIAP, in collaboration with the SDC
Page 90 and 91: CHAPTER 6 Pest management in rice G
Page 92 and 93: Table 6.2 Major natural enemies of
Page 94 and 95: (Walker). The yellow stem borer (S.
Page 96 and 97: Direct seeded rice is more suscepti
Page 98: 1.5-12.5 times as many wet season f
Page 101 and 102: Many of the problems associated wit
Page 103 and 104: The desired number of plants establ
Page 105 and 106: with 3-4 blades per row. The major
Page 107 and 108: large numbers of eggs and fry at th
Page 109 and 110:
Trap pond data collected from Kompa
Page 111 and 112:
Ricefield culture fisheries 3 In ar
Page 113 and 114:
Fish culture can therefore be used
Page 115 and 116:
Additional labor and draft power is
Page 117 and 118:
drilling for underground water, and
Page 119:
Helmers K, Bleakely R, Sakkunthea S
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