INTRODUCTION

Rice (Oryza sativa L.) began to be cultivated about 10,000 years ago in humid regions of tropical and subtropical Asia (Acevedo et al., 2006). As for its taxonomic classification, rice belongs to the family Poaceae, genus Oryza and species sativa. There are two cultivated species, Asian rice (Oryza sativa L.) and African rice (Oryza gla-berrima Steud.). In Asian rice, two subspecies are distinguished, indica and japonica (Paredes et al., 2021). The rice was introduced in Paraguay by Jesuit missionaries in the eighteenth century, around 1750. In its beginnings, the yield obtained was approximately 20 times the amount of grain sown (Rengger, 2010).

In 2022, the area planted with irrigated rice was 205,744 ha, from which a total production of 975,069 tons was obtained. The area dedicated to this crop, from 2008 to 2022 increased 507.5% and total production had an increase of 573.9%. The main cultivation areas are located in the departments of Itapúa, Misiones, Ñeembucú, and Paraguarí (Dirección de Censos y Estadísticas Agropecuarias/ Ministerio de Agricultura y Ganadería, [DCEA/ MAG] 2024).

Paraguay does not have its own varieties in the irrigated rice category. It introduces foreign varieties from neighboring countries with similar environmental conditions. Currently, there are 30 varieties registered in Paraguay, most of which come from Brazil: 11 varieties from Instituto Riograndense do Arroz (IRGA), 5 varieties from Santa Catarina Sementes, and 2 varieties from Embrapa. 5 varieties come from Ricetec SA, an American supplier, and 7 varieties from other suppliers. The most widely planted varieties in Paraguay are IRGA 424, IRGA 417, and PUITA, which are developed at the IRGA in Brazil (Arrua and Ortega, 2021).

In order to develop Paraguay’s own rice variety, in 2009, the KOPIA Paraguay Center, in cooperation with the Paraguayan Institute of Agricultural Technology (IPTA), introduced 200 rice breeding lines from the International Rice Research Institute (IRRI) in Manila Philippines. Since then, several rigorous selections of lines with high productive quality parameters have been carried out. From these selections, line 81346 -22-1-1-1 under the name of CEA- 5K-PUNTA variety was finally obtained and registered in the National Plant and Seed Quality and Health Service (SENAVE) variety list (IPTA/KOPIA, 2021).

Regarding the overall average yield of rice cultivation at the country level, during the past 9 years, it has been between 6,300 and 6,700 kg/ha (DCEA/MAG, 2022). Over the years, the amount of national production has been increasing, which has occurred at the same time as technological progress has allowed the expansion of cultivation to new areas. However, the number of small-scale rice farmers has been decreasing due to economic instability, the lack of technical assistance, and the lack of a proper land tenure system (Ogasawara, 2017).

Generally, the minimum rice cultivation area in Paraguay is as large as 8 to 50 ha, even for small-scale farmers, which makes it necessary to use machinery. However, renting machinery is not always available, and even if so, it represents a high cost for them. As a result, the application of chemical products is conducted manually with a knapsack sprayer (Arrua and Ortega, 2021).

Rice is an almost essential ingredient in Paraguayan rural families’ diets. Approximately 66.6% consume it at least once a week, 26.7% twice a week, and 3.7% almost daily. Only 3% of the country’s rural population does not consume it (Caputo, 2012). However, it is estimated that 80% of Paraguay’s rice production is exported, leaving the rest for domestic consumption (Quintana and Gutierrez, 2022).

This study was carried out to determine the impact of the KOPIA project on the increase of small-scale farmers’ income in Paraguay. Technical guidance was provided on the time and method of pesticide and herbicide application, as well as the types and dosage of fertilizers to be applied so that rice cultivation could be adapted to local conditions in Paraguay.

MATERIALS AND METHODS

Sowing and harvest.

The rice variety sown in the pilot village is CEA-5K-PUNTA. It was done from late August to November 2022, corresponding to the rice sowing season. Harvesting was done from January to April 2023.

Places of rice cultivation.

The average rice yields and the value of production was examined in five regions: Santa Rosa, Eusebio Ayala, Coronel Bogado, Santa Maria, and Yaguaron. For every region, the production or value of production was averaged for ten representative farmers of the pilot villages, meaning those who participated in the project. In the same regions, the production and value of production were also averaged for ten conventional farmers, meaning those who did not participate in KOPIA's program.

Calculation of productivity and value of production.

The increase in productivity and value of production was calculated using the Difference in Differences (DID) method (Abadie, 2005).

*Value of production = Production × selling price (US$).

Fertilizer.

NPK (05-25-25) was applied at 300 kg/ha at the sowing stage, and UREA (46-00-00) was applied at 125 kg/ha at the beginning of the tillering stage and the beginning of the heading stage, respectively.

Agricultural chemicals.

Table 1 shows the recommended dosage of chemical products of herbicides, insecticides, fungicides, and adherents for rice cultivation recommended to growers.

Others.

The main weeds that attack the rice fields and the applicable pesticide information are shown in Table 2. The main pests that attack the rice fields and the applicable pesticide information are shown in Table 3. This information was provided to the farmers in the pilot villages.

RESULTS AND DISCUSSION

In 2022/2023, the average yield per hectare in the pilot villages was 794.50 kg/10a, which represents an increase of 66.5% compared to the yield of 477.17 kg/10a for IRGA 424, the variety cultivated before the project started (Tables 4, 5). The increase in the value of production for the pilot village project was 65.1% when analyzed by the Difference in Differences Method described in the Materials and Methods (Tables 6, 7).

In Paraguay, rice seeds are sowed directly in dry fields and after the sprouting, water is supplied, so weeds are a big problem compared to when transplanting seedlings. The most problematic weed is Oryza sativa or red rice, which is of the same species as the cultivated rice and cannot be controlled with selective herbicides. Another challenging weed is Ludwigia bonariensis, which is native to South America and thrives in flooded soils (Tarrago et al., 2018). In Paraguay, weed control has a major impact on rice productivity, especially where rice is grown in succession.

According to Zelaya (2021), the main pathogens that affect the irrigated rice yield in the district of Coronel Bogado, Department of Itapúa, are Magnaporthe oryzae and Bipolaris oryzae. The intensity of the damage of these pathogens to the panicle increases in the rice from latesown fields. In addition, regarding the presence of fungi associated with rice grain spotting such as Bipolaris spp., Quintana et al. (2016) report Bipolaris oryzae, Alternaria padwickii, Microdochium oryzae, Cercospora spp., and Pyricularia oryzae as the main fungi that attack rice crop leaves in the Departments of Itapua, Misiones, and Caazapá. The incidence of these fungi is related to high humidity and temperature.

The main pests found in the rice plots were Oebalus poecilus, Tribraca limbativentris, Spodoptera spp., and Perichares philetes. This coincides with Ortiz (2013), who mentions that the most common pests in irrigated rice in the district of General Artigas, Department of Itapúa are Oebalus poecilus, Tibraca limbativentris, Spodoptera frugiperda, Nymphula indomitalis, and Perichares philetes. For these, KOPIA recommended spraying Thiamethoxan 70% WP (Table 3). Regarding the pests mentioned above, Oebalus poecilus (Heteroptera: Pentatomidae) feeds on rice grains and can cause quantitative or qualitative damage (Ferreira et al., 2002). During flowering, it causes the formation of stunted or empty grains. In the milk stage, it sucks out part or all of the grain contents (quantitative loss), which leads to a reduction in the germination rate and commercial quality of the grain (qualitative loss) (Barrigossi, 2008;Ferreira and Barrigossi, 2006). Tibraca lim- bativentris attacks rice plants 20 days after germination, causing partial or total death of the central part of the stem (Ferreira et al., 1997). Nymphula indomitalis occurs more frequently at the beginning of the cultivation, and its attack decreases during the reproductive phase of the crop when it is no longer suitable for the development of the larvae. Perichares philetes usually attacks in December (Ortiz, 2013). Oryzophagus oryzae is the most common pest observed during the post-sowing to harvest period. It feeds on the endosperm of the rice grain, causing the grain to be punctured by this insect’s mouthparts and resulting in rice grains with a yellowish semicircle in their center. Infestation by Oryzophagus oryzae begins shortly after flowering and continues until harvest when the contaminated rice becomes spotted rice or mottled rice if the attack occurs during the spring phase (Pazini et al., 2022). Spodoptera frugiperda (Lepidoptera: Noctuidae) also affects irrigated rice. It usually appears at the early stage of the crop before flood irrigation, cutting plants at the soil level and destroying large areas, resulting in yield reduction (Botton et al., 1998). Some years its population reaches high levels and can completely destroy the crop. The caterpillars feed preferentially on the weed Echinochloa spp. and start attacking the rice after the invasive plants have been eliminated with herbicides (Botton et al. 1998). In fields where rice is also growing in ridges, the attack may extend to the panicle emergence stage, because the caterpillars move to these sites after the field has been flooded.

Many factors affect the productivity of rice, including variety, soil quality, amount of fertilizer applied, and climate (Tascon and García, 1985). Soil analysis in the localities of Coronel Bogado, Santa Maria, Santa Rosa, Yaguaron, and Eusebio Ayala revealed that these soils had a slightly acid pH, a moderate amount of organic matter, and a low level of phosphorus and potassium. Therefore, the application and incorporation of 1,500 kg/ha of agricultural lime and the application of 00-70-36 kg/ha of N, P₂O₅, and K₂O, respectively, were recommended. Also, 25 kg/ha of nitrogen at 30 days after planting and a second application of 25 kg/ha at 60 days.

The CEA-5K-PUNTA variety was compared to the IRGA 424 in three locations (Eusebio Ayala, General Delgado, and Caapucú), with similar results in the categories of plant height, panicle length, and numbers of tillers per plant. The ranges are as follows: for plant height, 23 to 25 cm; for panicle length, 23 to 26 cm; and number of tillers per plant, 23 to 24 cm. (Instituto Paraguayo de Tecnología Agraria/Centro KOPIA Paraguay [IPTA/KOPIA], 2021). The significance of this study relies on that it shows that rice cultivation with the proposed method, using the recommended fertilizers and pesticides, and using the CEA- 5K-PUNTA variety (which is more productive than the IRGA 424 variety commonly grown in Paraguay), is more productive than the conventional variety and conventional cultivation methods.

In this study, a financial analysis was conducted on the agricultural inputs and cultivation methods used to cultivate the ‘CEA-5K-PUNTA’ rice variety in the pilot villages (Table 8). The average cost of renting machinery for rice farming was determined by inquiring four farmers. The financial analysis was based on the paddy fields within the project where the chemicals provided were applied, as stated in Table 8. Their productivity was examined from late August 2022 to January-April 2023. The average production cost per hectare was estimated at US$597.25, which is similar to the production cost mentioned by Arrua and Ortega (2021) of approximately US$555 per hectare when considering inputs, sowing machines, and harvesting machine rental. Of the gross profit of 1,685.3 US$/ha, the production cost was of 597.25 US$/ha. Therefore, the net profit per hectare for a farmer who does not rent land is US$1,088.05.

적 요

이 연구는 2021년 7월 1일부터 2024년 6월 말까지 진행된 KOPIA 파라과이 센터 벼 시범마을 사업의 일부로 산타 로사, 에우세비오아잘라, 코넬보가도, 산타 마리아, 야구아론 등 5개 지역 벼 시범마을 재배지에서 2022년 8월 말경부터 CEA-5KPUNTA 품종을 파종을 하고 2023년 1월부터 4월까지 수확한 벼의 평균 수확량과 생산액을 조사하였다.

시범마을 농가에는 토양분석을 하여 농가 별 적정 시비량과 살포시기를 알려주었다. 또한 주로 발생하는 해충, 병, 잡초에 대한 정보 및 이를 방제하는 시기와 살포 횟수에 대한 정보를 제공하였다. 또한 물관리와 제초 방법에 대한 기술지도를 하 였다.

2022/2023년의 시범마을의 10a당 평균 생산량을 조사한 결 과, 사업이 시작되기 전인 2019/2020년 관행 품종인 IRGA 424의 수확량은 477.17 kg에 비하여 2022/2023년 CEA-5K PUNTA 품종의 수확량은 794.50 kg 으로 시범마을 농가의 10a당 생산량이 시범사업 전(2020/2021)에 비해 66.5% 증가하 였다. 시범마을 벼 생산액 증가율을 Difference in Differences 방법으로 분석한 결과 시범마을 벼 생산액 증가율은 65.1%로 나타났다.

이 연구에서 2022년 8월 말경부터 2023년 1월부터 4월까지 생산성을 조사한 논에 투입한 농자재를 바탕으로 경제성 분석 을 한 결과 비용은 총 597.25 US$/ha이며, 조수익이 1,685.3 US$/ha 이었다. 따라서 ha당 순수익은 1,088.05 US$ 이다.