Ebrahim Rezaei; Morteza Sam Daliri; Hamid Reza Mobasser; Amir Abbas Mousavi Mirkolaei; Morteza Moballeghi
Abstract
Introduction
Rice (Oryza sativa L) is recognized as an important food product in the world. The survival of approximately 3 billion people depends on the production of this crop. Increasing ...
Read More
Introduction
Rice (Oryza sativa L) is recognized as an important food product in the world. The survival of approximately 3 billion people depends on the production of this crop. Increasing yield and sustainable production of rice is necessary for food security in the world. The transplanting of rice seedlings in Iran is by machine and manual-traditional. Machine transplanting is a promising technology that is more efficient and requires less labor than traditional manual transplanting. Having little land and the poor financial status of farmers are among the shortcomings of adopting this technology. Rice production is determined mostly by the soil. Soil is one of the most important environmental factors and the main source of nutrients and water for the growth of plants. Decreasing soil quality will reduce rice production. Maintaining soil properties at the desired level is one of the important management issues. Determining the appropriate plant density is the most basic and critical consideration for high-yield rice planting. Because it can accelerate tillering in each plant, balance the variables and promote the harmonious growth of the plant and the plant community. By determining the optimal plant density, it is possible to achieve the maximum yield of the crop. The current study aims to determine the optimal plant density in two soils with different physicochemical properties in a region under manual and machine rice transplanting methods.
Materials and Methods
A split-split plot experiment was conducted based on a randomized complete block design with four replications in 2021 and 2022. The experimental site is located along the coast of the Caspian Sea (36°50′N, 52°83′E; 29 m asl) at the Faculty of Agriculture and Natural Resources of Qaemshahr Azad University, Mazandaran Province (Northern Iran). Physical and chemical properties of soil (first type soil and second type soil) as the main factor, planting method (manual and machine transplanting) as a sub-factor, and plant density (15.9, 20.8, and 27.8 plants m-2 with spaces of 30 × 21, 30 × 16, and 30 × 12 cm2, respectively) as a sub-sub-factor were studied. In the current experiment, phenological traits (the number of days from transplanting to the beginning of flowering and the beginning of flowering to maturity), root morphological characteristics (root length and root fresh weight in tillering, panicle initiation, and maturity stages), and other agronomical traits (panicle length, number of panicles m-2, total spikelet panicle-1, 1000 - grain weight, grain yield, straw yield and harvest index) were measured.
Results and Discussion
Results showed that in the panicle initiation stage, the maximum root length in 2022 was obtained at a density of 27.8 plants m-2 (23.9 cm). At the same stage, the maximum fresh weight of the root in 2022 was observed with the second type soil (66.2 g). In the maturity stage, the maximum root length was recorded with the second type of soil during manual transplanting (22.4 cm). At the same stage, the highest root fresh weight was observed with the second type of soil at a density of 15.9 plants m-2 (86.4 g). The highest number of panicles m-2 in the second type of soil was obtained, respectively, during machine transplanting with a density of 27.8 plants m-2 (554.6 panicles) and during manual transplanting with the same plant density (547.4 panicles). The maximum total number of spikelets panicle-1 was observed in the first type of soil during manual transplanting and the density of 27 plants m-2 (134.1 spikelets), which was due to the number of panicles m-2 (427.0 panicles). The minimum 1000- grain weight in 2021 was obtained with the first type of soil during manual transplanting (26.6 g). The grain yield in the second type soil was 8.7% higher than the first type soil. Also, the highest grain yield was observed at a density of 27.8 plants m-2 (8687 kg ha-1).
Conclusion
Based on the results obtained in the present study, the second type of soil and a density of 27.8 plants m-2 are separately suggested to achieve the highest grain yield.
