Environmental impacts of transgenic Bt rice and non-Bt rice cultivars in northern Iran

Rice cultivation and processing: Highlights from a life cycle thinking perspective

The agri-food sector needs both water and energy and it also contributes to greenhouse gas (GHG) emissions; among the various activities within this sector, rice production has a particularly significant impact on the environment. Life Cycle Assessment (LCA) is one of the widely used approaches for evaluating the environmental impacts of a product, and as such, it is useful for examining the impacts of the rice industry. In recent years, LCA has been increasingly utilized to provide detailed insight into rice production processes. This review focuses on the application of LCA in rice production. Rice LCA studies were gathered in Scopus®. A total of 76 papers were examined up to the end of 2022. Most studies have evaluated the environmental impact of rice production and identified problem areas and opportunities for improvement. But there is a discrepancy in inputs considered, multifunctionality, emissions estimation and use of FU, which makes it challenging to compare LCA results, while some key aspects such as loss of biodiversity and variation of soil organic carbon and fertility are often not considered or roughly modelled. Only a small number (13 studies) evaluated economic consequences and investigated the impact of rice production on biodiversity (4 studies), indicating a stronger focus on environmental rather than socioeconomic aspects and limitations in evaluating certain environmental effects such as biodiversity and soil fertility.

Selection of ideotype to increase yield potential of GM and non-GM rice cultivars

Using classical breeding, plant breeders envision a plant type whose yield they aim to enhance by selecting for individual traits to create model/ideal plants or ideotypes. To achieve this, those factors restricting yield need to be identified and controlled through the use of new technologies to achieve the desired ideotype. This study aimed to determine the ideotype of seven genetically modified (GM) and non-GM rice (Oryza sativa L.) cultivars. Field experiments were carried out in three isolated regions in the north of Iran under the Iranian bio-safety standard protocol. Four of the GM cultivars carried the cry1Ab gene in the vegetative stage while three non-GM cultivars served as the control. R² values showed that five, six and seven variables in Sari, Amol and Rasht regions accounted for 63 %, 52 % and 74 % of paddy yield variation, respectively. In the same three regions, paddy yield variation due to white heads accounted for 28.38 %, 8.45 % and 3.95 % of the total variation in paddy yield, respectively. The total estimated variation in paddy yield in Sari, Amol and Rasht was 1810.50, 2377.6 and 2176.47 kg ha^-1, respectively. Average data over the three regions indicated that highest loss in paddy yield was observed in non-GM 'Nemat', 'Khazar' and 'Tarom Hashemi'. GM cultivars derived from 'Khazar' showed significantly lower paddy yield loss than the non-GM parent. Dead heart, a condition that occurs in the vegetative stage in which the stem borer larva enters the stem and feeds on the growing shoot, causing the central shoot to dry, as well as white heads, which is a condition in which whole ear heads of adult plants become dry and yield chaffy grains, in all three regions were important variables contributing to paddy yield loss. In the future, producing GM rice resistant to striped stem borer with an active promoter in the reproductive growth stage might allow farmers to reduce a significant part of paddy yield loss resulting from white heads, which is directly negatively correlated with filled spikelets per panicle (R² = -0.57**), in order to achieve an ideotype.