A facile and cheaper method to measure root angle of rice and wheat

Abstract

Genetic improvement in root system architecture (RSA) is an important trait to achieve stability of grain yield in water-deficit stress environments. Deep rooting is a major component trait that contributes to dehydration avoidance under drought in most crops. Due to the difficulty in the phenotyping for deep rooting, genetic variability in deep rooting is less exploited in genetic improvement programme. Root angle is a surrogate for deep rooting. Here, we report a novel method to measure root angle which is easy, robust and cheaper. By using this method, 56 wheat and 29 rice genotypes were phenotyped for root angle under field conditions. Wide variability in root angle was observed among rice and wheat genotypes. In rice, about 58% of crown roots were having shallow angle (<40°), while in wheat, about 67% of the crown roots were in deep rooting angle (>60°). This method could categorize the previously known shallow rooted rice cv. IR6 4 in to shallow root category with >90% of its crown root with an angle of <40°. Among the rice genotypes, BAM 2574, produced >60% of crown roots with >60° and identified as deep-rooted genotype. In wheat CL 3791, CL 3817 and CL 3823 were identified as deep-rooted genotypes. This method issuitable for high throughput phenotyping of root angle in natural field conditions.

Root traits and biomass production of drought‐resistant and drought‐sensitive arabica coffee varieties growing under contrasting watering regimes

“…This is because these root traits are among the root characteristics that facilitate a larger soil volume exploration for water extraction, reducing the sharp water potential gradient and ameliorating water limitations in plants (Agee et al., 2021). For example, long roots and narrow RAs can increase root growth at depth, where more moisture content is available, and improve water uptake during drought stress in plants (Alagoz et al., 2023; Sakhare et al., 2019). Nevertheless, Ramos and Carvalho (1997) studied 29 coffee genotypes, associated drought resistance with large root dry mass, but not with long root.…”

“…LRN and LRL were measured by counting all lateral roots of each sampled seedling and measuring their lengths by using a ruler, respectively. RA and RV were measured by using a modified protractor with an angle range of 0˚-90˚on both sides of the 90˚line as described in Sakhare et al (2019) and water displacement method in a 200-mL graduated cylinder filled with water, respectively. RDW and shoot dry weight (SDW) were also measured after ovendrying at 75˚C for 24 h. Thereafter, total fresh weight (TFW), total dry weight (TDW), root-mass ratio (RMR), root-shoot ratio (RSR), root density (RD), specific root length (SRL), and RLD were calculated from the data of fresh and dry weights, root length, RV, and soil volume.…”

“…However, some varieties (genotypes) show a significant resilience under drought conditions by developing a deep and vigorous root system and increasing water uptake, closing stomata and growing small leaves and reducing water loss in transpiration (Kozlowski & Pallardy, 2002), or osmotic adjustment and/or changes in cell well elasticity and maintaining turgor (Turner, 2018;Venkataramanan & Ramaiah, 1987). Studies have shown a varietal difference in drought stress responses in coffee (Gessese, 2006;Worku & Astatkie, 2010a) and a genetic variation in root traits and their implications for drought adaptations in other crops, for example, in cowpea, potato, rice, and wheat (Boguszewska-Mańkowska et al, 2020;Manschadi et al, 2008;Sakhare et al, 2019;Tatsumi et al, 2019). Burkhardt et al (2007) also postulated various strategies for drought resistance among wild arabica coffee populations growing in different agro-ecologies of Ethiopia.…”