amir ali kavand; ahmad zare; amin lotfi jalal- abadi
Abstract
Abstract
Introduction
A significant portion of rice cultivation methods worldwide is conducted through direct seeded rice (DSR) due to labor shortages and the need to conserve water ...
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Abstract
Introduction
A significant portion of rice cultivation methods worldwide is conducted through direct seeded rice (DSR) due to labor shortages and the need to conserve water or lack of sufficient water access. One of the disadvantages of direct seeded rice method is severe weed infestation, which, if not controlled, can lead to a significant reduction in yield. Therefore, the use of various methods, especially cultural methods alongside chemical methods, can be effective in integrated weed management.
Materials and methods
An experiment was conducted based on a factorial design within a completely randomized block design (RCBD) with three replications in 2022 growing season in the Mianab region Shush, Iran. The first factor included four seed rates (90, 120, 150, and 180 kg ha-1), the second factor included three rice cultivars (Anbarboo, Shiroodi, and Zeighami), and the herbicide treatment (application of bispyribac-sodium herbicide and no herbicide application). Dry weight of jungle-rice (Echinochloa colona (L.) Link) and Bearded Sprangletop Leptochloa fusca (L.) Kunth), the number of grains per panicle, the percentage of empty grains and grain yield were calculated and analyzed.
Result and Discussion:
The results of the mean comparison of the interaction effects of seed rates and different rice cultivars indicated that the highest dry weight of jungle-rice (78.5 g•m⁻²) was related to the 90 kg ha-1 seed rate treatment in the Anbarboo cultivar and the lowest (12.26 g•m⁻²) was related to the Zeighami cultivar under the 180 kg ha-1 seed rate conditions. The percentage reduction in dry weight of jungle-rice in the Anbarboo, Shiroodi, and Zeighami cultivars, when treated with a seed rate of 180 kg ha-1 compared to a seed rate of 90 kg ha-1, was 60%, 65%, and 82%, respectively. Additionally, the interaction effects of seed rates and herbicide treatments revealed that under both herbicide application and non-application conditions, the highest dry weight of jungle-rice (22 and 124 g•m⁻²) was observed at the 90 kg ha-1 seed rate and the lowest (3 and 41 g•m⁻²) at 180 kg ha-1 respectively. The results showed that bispyribac-sodium herbicide was not successful in controlling Bearded Sprangletop, and the dry weight of this weed significantly decreased with increasing seed rate. The number of grains per panicle in the Shiroodi and Zeighami cultivars was higher in the 120 and 150 kg ha-1 seed rate treatments compared to the 180 kg ha-1 treatment. The interaction effects of cultivars and herbicide treatments also showed that the highest number of grains per panicle was related to the Shiroodi cultivar under herbicide application conditions (80 grains per panicle). At lower seed rates (90 kg ha-1), due to increased weed competition, and at the seed rate of 180 kg/ha, due to increased intraspecific competition, the percentage of empty grain increased compared to seed rates of 120 and 150 kg ha-1. The percentage reduction in empty grain at the seed rate of 150 kg ha-1 in the Anbarboo and Zeighami cultivars compared to the seed rate of 90 kg ha-1 was 38% and 27%, respectively. The results of the interaction between seed rate and different rice cultivars showed that the highest grain yield (4194 and 4119 kg ha-1) was related to the Shiroodi cultivar at seed rates of 150 and 180 kg ha-1, respectively. In contrast, the lowest grain yield (1468 kg ha-1) was observed in the Zeighami cultivar at a seed rate of 90 kg ha-1.
Conclusion
Therefore, based on the results, the optimal treatment was the application of the Shiroodi cultivar with a seed rate of 120 to 150 kg ha-1 under herbicide application conditions.
