Document Type : Research Article
Authors
1
Department of Agronomy, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran
2
Department of Agronomy, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran
10.22067/jpp.2025.80593.1123
Abstract
Introduction:
Rice is one of the most important crops cultivated in Iran and in particular, North of the country. In recent years, reduced rainfall and adverse conditions of ground and surface waters has raised concerns about the feasibility of flooded rice cultivation method. On the other hand, yield loss by weeds under aerobic conditions is greater compared with the flooded systems, as weeds will emerge simultaneously with rice plants. Despite the more difficult weed management in aerobic rice as well as the limitations in its consequent cultivation in the same field, aerobic rice cultivation system still remains a feasible strategy to achieve sustainable production of rice under the inevitable adverse climatic conditions in the future. Therefore, the present study was carried out with the aim of evaluating the effect of various chemical management methods on weed control as well as growth characteristics of two rice cultivars of Neda and Fajr under aerobic conditions.
Materials and Methods
The experiment was conducted as a strip plot with three replicates at Dasht-e- Naz field, Sari in 2020-2021. Treatments included two cultivars (Neda and Fajr) and 10 levels of weed management including 1- bispyribac sodium (Novino) herbicide, 2- pendimethalin (Prowl) + bispyribac sodium (Novino) herbicides, 3- pendimethalin (Prowl) + bispyribac sodium (Clean Weed) herbicides, 4- pendimethalin (Stomp) + bispyribac sodium (Novino) herbicides, 5- pendimethalin (Stomp) + bispyribac sodium (Clean Weed) herbicides, 6- pendimethalin (Prowl) + bispyribac sodium (Clean Weed) + bispyribac sodium (Clean Weed) herbicides, 7- pendimethalin (Prowl) + bispyribac sodium (Clean Weed) + bensulfuron methyl (Londax) herbicides, 8- pendimethalin (Prowl) + bispyribac sodium (Novino) + bispyribac sodium (Novino) herbicides, 9- weed-free and 10- weedy check. In weedy checks, weeds were allowed to grow until the end of the growing season. Pre-emergence herbicides of Prowl and Stomp were sprayed 2 days after sowing. Also, Clean Weed and Novino herbicides were applied 21 days after sowing. Finally, 35 days after sowing, Clean Weed, Novino and Londax herbicides were sprayed in three-times application of herbicide treatment. Spraying was carried out using a chargeable Matabi knapsack sprayer equipped with a 8003 flat fan nozzle, calibration volume of 200 L ha-1 and 200 KPa pressure. In order to determine the growth characteristics of rice including dry weight, leaf area index and plant height, sampling was done at certain time intervals. Also, dry weight of weeds in each plot was recorded at the mentioned intervals.
Results and Discussion
The greatest plant height in Neda and Fajr was respectively 83.1 and 67.8 cm, which was observed in the weed- free treatment. The plant height varied from 56-73 cm in Neda and 41-60.5 cm in Fajr cultivar in different herbicide treatments. Also, plant height in weedy check in both Neda and Fajr cultivars was significantly lower than other treatments. In both rice cultivars and after the weed- free treatment, the greatest plant height and least time to 50% maximum height was recorded in three- times herbicide application treatments. In the weed- free treatment, leaf area index of Neda and Fajr cultivars reached its peak 71 days after sowing (both at the same time), and was 4.2 and 3.7, respectively. Three- times application of herbicides was ranked next after the weed-free treatment with leaf area indices of 3-3.2 in Fajr and 3.3-3.6 in Neda cultivar. Taking into account the weedy check, weed- free and herbicide treatments, the dry weight of Fajr cultivar ranged from 583.4 to 1640.6 g m-2, whereas these values in Neda varied between 1121.9 to 1968.4 g m-2. The results of this study showed that the most common weeds found in the field were velvetleaf (Abutilon theophrasti Medik.), musk melon (Cucumis melo L.), common purslane (Portulaca oleracea L.), barnyard grass (Echinochloa crus-galli (L.) P.Beauv.) and bermuda grass (Cynodon dactylon (L.) Pers.). Weed dry weight in weedy check and in the second place, single- herbicide application treatment was higher and increased more rapidly compared with other treatments. The increase in the dry weight of weeds in Fajr was higher than Neda cultivar. Also, next to the weed-free treatment with 5607 kg ha-1, grain yield was the highest when Prowl+ Novino+ Novino (4994 kg ha-1) and Prowl+ Clean Weed+ Clean Weed (5029 kg ha-1) treatments were applied.
Conclusions
Based on the results obtained from this study, cultivation of Neda cultivar as well as three-times application of herbicides (application of pre-emergence herbicide followed by two- times aaplication of a post-emergence herbicide) is recommended to improve the grain yield of rice under aerobic system.
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