Flooded rice yield as affected by levels of water salinity in different stages of its cycle

Thiago Isquierdo Fraga,Ibanor Anghinoni,Elio Marcolin,Felipe de Campos Carmona,Silvio Aymone Genro Junior

doi:10.1590/s0100-06832010000100018

Thiago Isquierdo Fraga, Ibanor Anghinoni + Show 3 more

Open Access

https://doi.org/10.1590/s0100-06832010000100018

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Abstract

Losses of productivity of flooded rice in the State of Rio Grande do Sul, Brazil, may occur in the Coastal Plains and in the Southern region due to the use of saline water from coastal rivers, ponds and the Laguna dos Patos lagoon, and the sensibility of the plants are variable according to its stage of development. The purpose of this research was to evaluate the production of rice grains and its components, spikelet sterility and the phenological development of rice at different levels of salinity in different periods of its cycle. The experiment was conducted in a greenhouse, in pots filled with 11 dm³ of an Albaqualf. The levels of salinity were 0.3 (control), 0.75, 1.5, 3.0 and 4.5 dS m-1 kept in the water layer by adding a salt solution of sodium chloride, except for the control, in different periods of rice development: tillering initiation to panicle initiation; tillering initiation to full flowering; tillering initiation to physiological maturity; panicle initiation to full flowering; panicle initiation to physiological maturity and full flowering to physiological maturity. The number of panicles per pot, the number of spikelets per panicle, the 1,000-kernel weight, the spikelet sterility, the grain yield and phenology were evaluated. All characteristics were negatively affected, in a quadratic manner, with increased salinity in all periods of rice development. Among the yield components evaluated, the one most closely related to grain yields of rice was the spikelet sterility.

Highlights

The area under rice cultivation in Rio Grande do Sul is about one million hectares, concentrated in the Southern half of the State (IRGA, 2008)
The number of panicles per pot, number of grains per panicle and 1,000-kernel weight decreased and spikelet sterility increased with increasing salinity in the different evaluation periods from V4 (Figure 1)
These effects were lower for the period of added salt from V4 to panicle initiation (PI) compared to the others, whose time under stress reached 49 days

Summary

Introduction

The area under rice cultivation in Rio Grande do Sul is about one million hectares, concentrated in the Southern half of the State (IRGA, 2008). In the Southern region and Coastal Plains, the source most often used for irrigation comes from the Laguna dos Patos lagoon, whose area is 10,360 km, the largest coastal lagoon in South America (Fernandes et al, 2005), with high potential for irrigation. December, January and February are the hottest months of the year and coincide with the rice fields irrigation time. During this period, with the decrease of the level of this lagoon, the entry of seawater occurs, resulting in an increase of salt concentration levels often harmful to the crop (Marcolin et al, 2005), which can potentially reach an area of about 200,000 ha of rice fields (Machado & Terres, 1995)

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