Relationship between weedy rice (Oryza sativa) infestation level and agronomic practices in Italian rice farms

Abstract

Weedy rice (Oryza sativa L.) is a troublesome rice (Oryza sativa L.) weed in Italy and in many other rice areas. The objective of this study was to correlate the O. sativa infestation level in northern Italy, the main European rice-growing area, with agricultural practices adopted by farmers by using data obtained from a farmer survey. In 2018 to 2019, a survey was carried out on 98 rice farms chosen to ensure different sizes, different cultivation practices, and variable degrees of O. sativa infestation. The following information was acquired: farm size; area cultivated with Clearfield® varieties; the most-adopted agronomic practices (type of tillage, crop rotation, type of sowing, water management, origin of seeds, adoption of stale seedbed, use of imazamox, presence of O. sativa resistant to imazamox); and level of O. sativa infestation: low (≤5 plants m−2), medium (>5 to 20 plants m−2), and high (>20 plants m−2). The data were analyzed through descriptive statistics and ordinal logistic regression to determine which agronomic practices influenced the level of O. sativa infestation. Farm clustering was also determined through two-step cluster analysis. Rice was cultivated as a monocrop and mainly sown in water, using purchased seeds, in plowed fields. More than half of the farms used the stale seedbed practice, and 63% adopted Clearfield® varieties, while about 45% of the farms reported imazamox-resistant O. sativa. The ordinal logistic regression underlined that use of a stale seedbed was correlated with the infestation level of O. sativa, and the two-step cluster analysis showed that the farms were mainly grouped based on the use of this technique. Most of the farms that used a stale seedbed had higher O. sativa infestation than those that did not use it, meaning that this practice was mainly applied in zones where O. sativa infestations were more serious.

Dynamics of weedy rice soil seedbank under different control strategies in Italian rice fields: survey and model study

“…Weedy rice ( Oryza sativa L.), also commonly referred to as “red rice” due to its red grain pericarp, is a noxious weed classified as a rice ( Oryza sativa L.) companion weed worldwide (Fogliatto et al 2020; Nadir et al 2017). Weedy rice infestation began its significant global spread after the shift from rice transplanting to direct seeding, which was fueled by water scarcity and the high labor costs associated with hand or mechanical weeding (Ferrero et al 2020; Ziska et al 2015). Weedy rice is characterized by a high genetic divergence that results in morphological and phenological differences across populations with specific traits which contribute to their weediness (Fogliatto et al 2011, 2012; Grimm et al 2020; Kanapeckas et al 2018).…”

“…A high weedy rice seed load forms a persistent soil seedbank, resulting in increased weedy rice infestation across many years (Chen et al 2017; Kraehmer et al 2016). Weedy rice seeds are also added to the soil seedbank through contaminated commercial or saved seed (Ferrero et al 2020; Fogliatto et al 2012; Rao et al 2017).…”

“…An inverse relationship between weedy rice emergence rate and depth of seed burial has been found: seeds lying on the soil surface showed an emergence rate of about 51% as opposed to only about 13% at a depth of 10 cm (Vidotto and Ferrero 2000). Crop rotation has proved to be one of the most effective systems to reduce the evolution of a specialized, highly competitive weed flora and to control overall infestation levels (Ferrero et al 2020; Kanatas 2020; Stein and Steinmann 2018). Previous studies found a significant decline in the weedy rice seedbank with rice rotation with non-flooded crops and application of an effective herbicide (Scherner et al 2018; Ziska et al 2015).…”

“…However, in many rice areas, such as in Italy, crop rotation is seldom practiced because of poorly drained soils (Fogliatto et al 2011). A recent survey conducted in the Italian rice area revealed that crop rotation was practiced only in 14% of the surveyed farms (Ferrero et al 2020).…”

Relationship between weedy rice (Oryza sativa) infestation level and agronomic practices in Italian rice farms – ERRATUM

“…In the original publication of this article (Ferrero et al 2020), the article type was misstated. The proper article type is "Special Issue Article.…”