Volume 12, Issue 4 (1-2023)
2023, 12(4): 169-184 |
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Islamic Azad University , drmobasser.neg@gmail.com
Abstract: (694 Views)
It is important to determine the appropriate planting density in the conditions of using old seedlings of paddy rice. For this purpose, a field experiment was conducted as a randomized complete block design at Qaemshahr, Northern Iran, in four replications and in two years, 2020 and 2021. Plant densities consisted of manual-traditional planting of up to 11 hills/m2 (with unequal planting spaces and common in the region) as control and manual-equidistant planting with 25 hills/m2 (with planting spaces of 20 × 20 cm and recommended by the Rice Research Institute of Iran) and machine-planting with 15.9, 20.8 and 20.8 hills/m2 (with planting spaces of 30 × 21, 30 × 16 and 30 × 12 cm, respectively). The paddy rice seedlings aged 45 d in manual-planting and 35 d in machine-planting. The results showed that the number of days from transplanting to flowering and flowering to maturity for machine-planting densities were greater than those of the control and 25 hills/m2 in manual-equidistant planting. The interaction effect of year × planting density was significant only for the flag leaf length and plant height. The greatest panicle length and flag leaf length were obtained when the rice plants were sown in a density of 25 hills/m2 in manual-equidistant planting. The greatest panicles/m2 and the percentage of grain-bearing spikelets were obtained when rice plants were sown by the machine. The maximum grain yield was obtained from planting density of 25 hills/m2 in manual-equidistant planting (8022 kg/ha). The planting densities of 15.9, 20.8 and 27.8 hills/m2 in machine planting with 8034, 8236 and 8168 kg/ha grain yield ranked next as they out-yielded the control by 19%, 19%, 21% and 21%, respectively. It was concluded that machine planting with planting densities of 15.9, 20.8 and 27.8 hills/m2 is advantageous, at least when using old paddy rice seedlings.
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