Abstract
Flood has an important effect on plant growth by affecting their physiologic and biochemical properties. Soybean is one of the main cultivated crops in the world and the United States is one of the largest soybean producers. However, soybean plant is sensitive to flood stress that may cause slow growth, low yield, small crop production and result in significant economic loss. Therefore, it is critical to develop soybean cultivars that are tolerant to flood. One of the current bottlenecks in developing new crop cultivars is slow and inaccurate plant phenotyping that limits the genetic gain. This study aimed to develop a low-cost 3D imaging system to quantify the variation in the growth and biomass of soybean due to flood at its early growth stages. Two cultivars of soybeans, i.e. flood tolerant and flood sensitive, were planted in plant pots in a controlled greenhouse. A low-cost 3D imaging system was developed to take measurements of plant architecture including plant height, plant canopy width, petiole length, and petiole angle. It was found that the measurement error of the 3D imaging system was 5.8% in length and 5.0% in angle, which was sufficiently accurate and useful in plant phenotyping. Collected data were used to monitor the development of soybean after flood treatment. Dry biomass of soybean plant was measured at the end of the vegetative stage (two months after emergence). Results show that four groups had a significant difference in plant height, plant canopy width, petiole length, and petiole angle. Flood stress at early stages of soybean accelerated the growth of the flood-resistant plants in height and the petiole angle, however, restrained the development in plant canopy width and the petiole length of flood-sensitive plants. The dry biomass of flood-sensitive plants was near two to three times lower than that of resistant plants at the end of the vegetative stage. The results indicate that the developed low-cost 3D imaging system has the potential for accurate measurements in plant architecture and dry biomass that may be used to improve the accuracy of plant phenotyping.
Highlights
Soybean [1] is the second largest crop grown in the United States with 36.4 million ha planted, yielding US$ 40.0 billion in 2017 (USDA-ERS, 2018)
The results indicate that flood stress at vegetative stage V1 had a significant impact on the accumulation of biomass, which may affect the crop development and cause yield loss
This study developed a cost-effective 3D imaging system to quantify the variation in soybean growth and biomass due to submergence stress at the early growth stage
Summary
Soybean [1] is the second largest crop grown in the United States with 36.4 million ha planted, yielding US$ 40.0 billion in 2017 (USDA-ERS, 2018). Sensors 2019, 19, 2682 to flood stress [2], which affects the physiologic and biochemical processes of soybeans, resulting in the reduction of the accumulation of dry matter (biomass) and seed yield. Many researchers have studied the morphological responses of crops under flood stress. Flood tolerant crop cultivars often grow taller under flood conditions than they are in controlled environments, the biomass accumulation is lower than those under control [5,6]. The increase in the petiole angle is the first visible symptom of the tolerant cultivars, followed by the increase in petiole length [5] in order to maximize the leaf area above the water [7]. Yield reduction was reported in soybean breeding or genetic studies when soybean suffers flood stress at different growth stages, for example, a 17–40%
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