**4. Results and discussion**

Certain insecticides like aldicarb, carbofuran and thiamethoxam, may cause a physiological effect promoting changes in certain processes in plant physiology, such as growth, morphol‐

The thiamethoxam can be applied in seed treatment, by spraying on leaves of plants or by soil application, being absorbed by the roots. Applied as a seed treatment, the thiamethox‐ am can promote the expression of the effect by stimulating root growth and increasing ger‐

mination rate, consequently, reducing the time for field crop establishment.

factors of this variability at the productivity levels (Mertz et al., 2009).

**2. Physiological changes in rice seeds exposed to low temperature at**

Rice is grown in diverse environmental conditions, but when compared to other cereals such as oats or wheat, is much more sensitive to low temperatures (Mertz et al., 2009). The occurrence of cold weather is one of the major problems when irrigated rice in Rio Grande do Sul - Brazil, is cultivated since the most of the cultivars in use are from tropical origin. The occurrence of low temperatures, together with the susceptibility of the materials used can cause serious damage to the establishment of the crop, reducing the initial stand and consequently favoring the establishment of weeds. The productivity of irrigated rice in Rio Grande do Sul has suffered strong oscillations over the years, caused in part by climatic con‐ ditions, where the occurrence of low temperatures has been one of the major determinants

On the other hand, hormone controllers have received increasingly more attention in agri‐ culture as the crop techniques develop, especially in high value crops. The bioactivators are complex organic substances that can alter the growth, capable to act on the transcription of DNA in plant, gene expression, membrane proteins, metabolic enzymes and mineral nutri‐ tion (Castro and Pereira, 2008). The thiamethoxam insecticide has shown positive effects such vigor expression increase, biomass accumulation, high photosynthetic rate and deeper

The aim of this work was to evaluate the influence of thiamethoxam in the rice crop and the potential benefits that treatment can provide, when rice seeds are subjected to low tempera‐

Three rice cultivars where used: two conventional (BR IRGA 417, BR IRGA 424) and one hybrid (Avax R.). The cultivars had the same physiological quality and were evaluated for tolerance to low temperature through the germination test. The seeds were treated with a commercial product containing 35 grams of thiamethoxam active ingredient per li‐ ter of product. The treatments were: Treatment 1 - untreated seeds; Treatment 2 - 100ml

ogy or plant biochemistry.

418 Insecticides - Development of Safer and More Effective Technologies

**germination**

roots (Cataneo, 2008).

ture during germination and emergence.

**3. Material and methods**

According to the results, the rice seeds cultivars BR IRGA 417, BR IRGA 424 and Avax R. treated with thiamethoxam, were superior in all tested temperatures, when compared to the values obtained in the zero dose (without application of thiamethoxam), varying only the intensity of this difference due to the dose used and the temperature.

By observing the data shown in Figure 3, it is found that the treated seeds showed signifi‐ cant increases in germination at different temperatures.

The temperatures of 15ºC and 13°C were the most adverse ones, but when the seeds are treated independent from the dose, they showed germination over the zero dose. At the dose of 200 mL/100 kg of seeds at a temperature of 15°C, there was an increase of 21 percent‐ age points, whereas at 13°C this increase was 37 percentage points. At temperatures of 25, 20 and 18ºC this increase was on average 7 percentage points when compared with the zero dose.

Figure 4 shows that seeds treated with thiamethoxam at different temperatures had posi‐ tive additions in relation to the zero dose. The results of this study confirm those ob‐ tained by Castro et al. (2007), working with soybeans, and those by Clavijo (2008) working with rice, when claiming that seeds treated with thiamethoxam had their germi‐ nation accelerated by stimulating the enzymes activity, besides of showing more uniform emergency and stand more uniform and better initial impulse. Also in soybean seeds, Cataneo (2008) observed that thiamethoxam accelerates germination, and induces further development of the embryonic axis. According to the results, rice seeds, cultivars BR IR‐ GA 417, BR IRGA 424 and Avax R. treated with thiamethoxam, were superior in all the tested temperatures, when compared to the values obtained at the zero dose (without ap‐ plication of thiamethoxam), varying only the intensity of this difference due to the dose used and temperature.

According to Figure 5, the results of cultivar AVAXI R, hybrid rice seeds when treated with thiamethoxam showed increases in relation to the dose zero. The dose 100mL/100 kg of seeds showed higher increases when compared with other doses at all studied tempera‐ tures, being of 28 percentage points at a temperature of 13°C which is the most drastic one,

Thiamethoxam: An Inseticide that Improve Seed Rice Germination at Low Temperature

http://dx.doi.org/10.5772/53207

421

**Figure 5.** Germination (%) rice seeds, cultivar Avax R., treated with thiamethoxam at different temperatures.

pests, winds, hail, attack of viruses and nutrient deficiency

It was observed that at all temperatures studied with product addition there was an increase in germination of the seeds (Figure 6). In average there were increases reaching up to 8 per‐ cent germination at 25 º C, 12 percentage points at 20 º C, 17 percentage points at 18 º C and 34 percentage points in the germination test with temperatures of 15 and 13 ° C when com‐ pared with seedlings from untreated seeds. Besides increasing the percentage of germina‐ tion, there is also the activating effect of the product, with the increase in size of roots and shoots (Figure 7). This increase may provide a more rapid and uniform establishment of the crop. According to Clavijo (2008), the thiamethoxam is transported inside the plant through its cells and activates several physiological reactions like protein expression. These proteins interact with various mechanisms of defense related to the plant stresses, allowing to a bet‐ ter deal with adverse conditions such as drought, low pH, high soil salinity, free radicals, stress by high or low temperature, toxic effects of high levels of aluminum injury caused by

comparing the doses 100mL/100kg of seeds with the zero dose.

**Figure 3.** Germination (%) rice seeds, cultivar BR IRGA 417, treated with thiamethoxam at different temperatures.

**Figure 4.** Germination (%) rice seeds, cultivar BR IRGA 424, treated with thiamethoxam at different temperatures.

According to Figure 5, the results of cultivar AVAXI R, hybrid rice seeds when treated with thiamethoxam showed increases in relation to the dose zero. The dose 100mL/100 kg of seeds showed higher increases when compared with other doses at all studied tempera‐ tures, being of 28 percentage points at a temperature of 13°C which is the most drastic one, comparing the doses 100mL/100kg of seeds with the zero dose.

**Figure 5.** Germination (%) rice seeds, cultivar Avax R., treated with thiamethoxam at different temperatures.

**Figure 3.** Germination (%) rice seeds, cultivar BR IRGA 417, treated with thiamethoxam at different temperatures.

420 Insecticides - Development of Safer and More Effective Technologies

**Figure 4.** Germination (%) rice seeds, cultivar BR IRGA 424, treated with thiamethoxam at different temperatures.

It was observed that at all temperatures studied with product addition there was an increase in germination of the seeds (Figure 6). In average there were increases reaching up to 8 per‐ cent germination at 25 º C, 12 percentage points at 20 º C, 17 percentage points at 18 º C and 34 percentage points in the germination test with temperatures of 15 and 13 ° C when com‐ pared with seedlings from untreated seeds. Besides increasing the percentage of germina‐ tion, there is also the activating effect of the product, with the increase in size of roots and shoots (Figure 7). This increase may provide a more rapid and uniform establishment of the crop. According to Clavijo (2008), the thiamethoxam is transported inside the plant through its cells and activates several physiological reactions like protein expression. These proteins interact with various mechanisms of defense related to the plant stresses, allowing to a bet‐ ter deal with adverse conditions such as drought, low pH, high soil salinity, free radicals, stress by high or low temperature, toxic effects of high levels of aluminum injury caused by pests, winds, hail, attack of viruses and nutrient deficiency

**5. Conclusion**

**Author details**

**References**

Andréia da Silva Almeida1

Geri Eduardo Meneghello4

1 Seed Care Institute- Syngenta, Brazil

4 Universidade Federal de Pelotas, Brazil

5 Syngenta Crop Protection, Brazil

sementes\_web.pdf

lômbia, 2008.196p.

ba: ESALQ, 2006. 46p. (Série Produtor Rural, 32).

123-192.

3 Syngenta Crop Protection- Seed Care Institute, Brazil

seeds.

The rice seed treatment with thiamethoxam positively favors the physiological quality of

The doses of 100 and 200 mL of product per 100 kg of rice seed are more effective to im‐ prove the physiological performance of rice seeds, in temperatures between 13 and 25 °C.

, João Carlos Nunes3

Thiamethoxam: An Inseticide that Improve Seed Rice Germination at Low Temperature

,

http://dx.doi.org/10.5772/53207

423

, Francisco Amaral Villela2

2 PPG Ciência e Tecnologia de Sementes, Universidade Federal de Pelotas, Brazil

[1] Brasil. Ministério da Agricultura e Reforma Agrária. Regras para análise de se‐ mentes. http://www.agricultura.gov.br/images/MAPA/arquivos\_portal/ACS/

[2] Cataneo, A C. Ação do Tiametoxam (Thiametoxam) sobre a germinação de sementes de soja (*Glycine max*.L): Enzimas envolvidas na mobilização de reservas e na proteção contra situação de estresse (deficiência hídrica, salinidade e presença de alumínio). Tiametoxam: uma revolução na agricultura brasileira.: Gazzoni, D.L. (Ed.)., 2008, p.

[3] Clavijo, J. Tiametoxam: um nuevo concepto em vigor y productividad. Bogotá, Co‐

[4] Castro, P.R.C. Agroquímicos de controle hormonal na agricultura tropical. Piracica‐

[5] Castro, P. R. C.; Pereira, M.A. . Bioativadores na agricultura. Tiametoxam: uma revo‐

lução na agricultura brasileira.: Gazzoni, D.L. (Ed.). 2008, p. 118-126.

and Adilson Jauer5

**Figure 6.** Average germination, cultivar BR IRGA 417, under different doses of thiamethoxam.

**Figure 7.** Growth of rice seedlings exposed to different doses of thiamethoxam temperatures of 13 and 25°C
