Can 2,4-D promote the hormesis effect in upland rice?

This study aimed to evaluate the influence of low doses of 2,4-D on the agronomic traits of upland rice applied at different stages of crop growth. The work was carried out in a randomized completly blocks, and consisted of the application of 5 low doses of the 2,4-D herbicide (0, 0.68, 1.36, 2.04, 3.40 and 5.44 g acid equivalent (e.a.) ha-1) in two stages of rice development (tillering and floral differentiation). Nitrogen contentes in leaves, SPAD index and yield are higher when low doses of 2,4-D is applied in the tillering stage. Application of 2,4-D at a dose of 2.04 g a.e ha-1 results in a 19% increase in the number of spikelet per panicle. On the other hand, there is no effect of the application of low doses of 2,4-D on height, number of stems, active tillering and weight of 100 seeds. Our results contribute to increase knowledge of the hormesis effect in plants in order to increase crop yield.

Can the application of low doses of paraquat induce the hormesis effect in upland rice?

This study aimed to verify the effects of the application of paraquat low doses on the agronomic traits of upland rice in two different application modes. The treatments consisted of a combination of 6 low doses of the paraquat (0; 20; 40; 60; 80 and 120 g a.i. ha-1) and 2 application modes of low doses a) single application performed between active tillering and floral differentiation b) application split into four applications, the first being carried out at the beginning of active tillering, the second being carried out between active tillering and floral differentiation, the third application carried out after floral differentiation and the fourth application carried out after flowering with 25% of the dose in each application. The application of low doses of paraquat does not promote the hormesis effect of upland rice. The increase in the frequency of the plant to the herbicide caused by the splitting of applications negatively affected the plant height, number of spikelets per panicle, yield, leaf nitrogen and sulfur as the low doses levels were increased. On the other hand, there is no influence of paraquat low doses levels when single applied to the agronomic traits of upland rice.

Does the glufosinate-ammonium herbicide have the potential to induce the hormesis effect in upland rice?

This study aimed to evaluate the effects of low doses of the herbicide glufosinate-ammonium in different application modes in the vegetative development of upland rice. The treatment consisted of a combination of five low doses (0; 15; 30; 60; and 100 g a.i. ha-1) of the herbicide glufosinate-ammonium and four application modes of the low doses: single between active tillering (AT) and floral differentiation (FD); single after FD; split in two (the first at the beginning of the AT and the second between AT and FD; split in three (the first at the beginning of the AT, the second between the AT and the FD and the third after the FD, with. There was no hormesis effect on rice crop due to low doses of glufosinate-ammonium. The vegetative development of rice plants was reduced by the application of low doses in all application modes with lower plant height, dry weight, number of panicles, and effective tiller.

Can the application of low doses of glyphosate induce the hormesis effect in upland rice?

The aim of this research was to verify the effect of glyphosate low doses on leaf macronutrient levels and vegetative traits of upland rice in two growth stages. The treatments were arranged in 2 × 6 factorial scheme. The first factor consisted of applications in two growth stages of rice crop (tillering and floral differentiation) and the second factor was the low doses of glyphosate (0, 10, 20, 40, 70 and 100 g e.a. ha-1). In full bloom, the chlorophyll content was determined in a sample of 30 flag leaves. In these leaves, the contents of macronutrients were determined. At the maturity of the rice plant, the stem count was performed per m2, effective tiller and the plant height was measured. The low doses did not influence the leaf content of macronutrients. The plant height was reduced with an increase in the low doses of glyphosate, having a greater effect on the floral differentiation stage. When applied low doses of glyphosate at the floral differentiation stage, chlorophyll content increases and when applied to tillering there is a linear decrease in chlorophyll content. The number of stems increases with the application of low doses at floral differentiation.

Optimum Sowing Date and Genotype Testing for Upland Rice Production in Brazil.

A better understanding of widespread agricultural practices adopted in the region of Ribeira Valley, São Paulo, Brazil for upland rice (Oryza sativa L.) production is needed. The objectives of this study were to determine the optimum sowing date and highest yielding genotypes for rice production. Treatments included four upland rice genotypes (ANA 5011, AN-Cambará, Moti-Amarelo, and Moti-Branco) and four sowing dates (October, November, December, and January) in 2011 and 2012. The results of the study showed that genotype ANA 5011 had the earliest maturity, while the Moti genotypes had the latest maturity in all sowing dates. The Moti genotypes were found to have greater plant height and 1,000-grain weight than the other two genotypes. In contrast, the Moti genotypes had fewer panicles m-2, fewer total filled and total numbers of spikelets panicle-1, and lower final yield. The genotype AN-Cambará had the highest number of tillers, filled and total number of spikelets panicle-1, panicle m-2, and the highest yield. Sowing in either November or December was found to be the most suitable dates for rice cultivation for all genotypes. In conclusion, the AN-Cambará genotype was found to have the highest yield potential for the region among all genotypes studied.