Root Morpho-physiological Traits Research Articles

Rice Cultivar Renewal Reduces Methane Emissions by Improving Root Traits and Optimizing Photosynthetic Carbon Allocation

Cultivar renewal (CR) contributes greatly to rice yield increase in China and even in the world. However, few studies were focused on the impact and mechanism of CR on field methane (CH4) emissions. A 2-year field experiment was conducted using 14 typical japonica rice cultivars released in the Yangtze River Basin of China during the last 70 years. The grain yield, root morphophysiological traits and their relationships with CH4 emissions were examined. The results showed that the grain yields of cultivars in the 1960–2010s increased by 18.8–93.9% while the CH4 emissions decreased by 9.5–41.2% compared with the 1950’s cultivars. The daily and cumulative CH4 emissions during the panicle differentiation stage (PD) were reduced significantly, which contributed greatly to the CH4 mitigation of the whole growing season. The CR notably increased root biomass, root/shoot ratio, root oxidation activity, and the total organic carbon in root exudates (ETOC), and decreased the ratios of ETOC/yield, ETOC/root biomass and ETOC/shoot biomass. Nitrogen fertilizer applied during panicle differentiation could improve the root physiology and decrease the ETOC/yield and ETOC/root, therefore reducing CH4 emissions. Our findings illustrated that CR reduced CH4 emissions by improving root traits and by optimizing the photosynthate allocation to biomass and grain yields. Applying nitrogen fertilizer during panicle differentiation could further mitigate the CH4 emissions in paddies.

Optimum Nitrogen Application Acclimatizes Root Morpho-Physiological Traits and Yield Potential in Rice under Subtropical Conditions

Nitrogen (N) is a highly essential macronutrient for plant root growth and grain yield (GY). To assess the relationship among N, root traits, and the yield of boro (dry season irrigated) rice, a pot experiment was performed in the Department of Agronomy, Bangladesh Agricultural University, Mymensingh, Bangladesh, during the boro rice season of 2020-2021. Three boro rice varieties, namely BRRI dhan29, Hira-2, and Binadhan-10, were planted at four N doses: 0 kg ha-1 (N0), 70 kg ha-1 (N70), 140 kg ha-1 (N140), and 210 kg ha-1 (N210). The experiment was conducted following a completely randomized design with three replicates. The varieties were evaluated for root number (RN), root length (RL), root volume (RV), root porosity (RP), leaf area index (LAI), total dry matter (TDM), and yield. The results indicated that the Binadhan-10, Hira-2, and BRRI dhan29 varieties produced better root characteristics under at the N140 and N210 levels. A substantial positive association was noticed between the grain yield and the root traits, except for root porosity. Based on the root traits and growth dynamics, Binadhan-10 performed the best at the N140 level and produced the highest grain yield (26.96 g pot-1), followed by Hira-2 (26.35 g pot-1) and BRRI dhan29 (25.90 g pot-1).

Polyphosphate application influences morpho-physiological root traits involved in P acquisition and durum wheat growth performance

BackgroundAmong phosphate (P) fertilizers, polyphosphates (PolyPs) have shown promising results in terms of crop yield and plant P nutrition. However, compared to conventional P inputs, very little is known on the impact of PolyPs fertilizers on below- and above-ground plant functional traits involved in P acquisition. This study aims to evaluate agro-physiological responses of durum wheat variety ´Karim´ under different PolyPs applications. Three PolyPs fertilizers (PolyA, PolyB, and PolyC) versus one orthophosphate (OrthoP) were applied at three doses; 30 (D30), 60 (D60), and 90 (D90) kg P/ha under controlled conditions.The PolyPs (especially PolyB and PolyC) application at D60 significantly increased morphophysiological root traits (e.g., RL: 42 and 130%; RSA:40 and 60%), shoot inorganic P (Pi) content (159 and 88%), and root P acquisition efficiency (471 and 296%) under PolyB and PolyC, respectively compared to unfertilized plants. Above-ground physiological parameters, mainly nutrient acquisition, chlorophyll content and chlorophyll fluorescence parameters were also improved under PolyB and PolyA application at D60. A significant and positive correlation between shoot Pi content and rhizosphere soil acid phosphatase activity was observed, which reveal the key role of these enzymes in PolyPs (A and B) use efficiency. Furthermore, increased P uptake/RL ratio along with shoot Pi indicates more efficient P allocation to shoots with less investment in root biomass production under PolyPs (especially A and B).ConclusionsUnder our experimental conditions, these findings report positive impacts of PolyPs on wheat growth performance, particularly on photosynthesis and nutrient acquisition at D60, along with modulation of root morpho-physiological traits likely responsible of P acquisition efficiency.

The Response of Grain Yield and Root Morphological and Physiological Traits to Nitrogen Levels in Paddy Rice.

Rice (Oryza sativa L.) is an important crop in China. Although it is known that its yield is restricted by nitrogen (N) supply, the response of the root system to N supply specifically has not been systematically explored. This study aimed to investigate the effect of N uptake on grain yield to clarify the relationships between root morphophysiological traits and N uptake, and to understand relation between phytohormones and root morphophysiological traits. Two N-efficient absorption cultivars (NEAs) and two N-inefficient absorption cultivars (NIAs) were grown in the field, and three N conditions, deficient N (60 kg ha–1), intermediate N (180 kg ha–1), and sufficient N (240 kg ha–1), were applied during the growing season. The results showed higher dry matter and grain yield in NEAs than in NIAs, which was mainly attributed to increased N uptake in the mid- and late growth stages under all N conditions. And NEAs have different root regulation methods to obtain higher N accumulation and yield under different N supply conditions. Under lower N conditions, compared with NIAs, NEAs shown greater total root length, root oxidation activity, and root active absorbing surface area and smaller root diameter owing to higher indole-3-acetic acid and cytokinin content and lower 1-aminocyclopropane-1-carboxylic acid content in the early growth stages to respond to low N stress faster, laying a morphophysiological basis for its high N-uptake capacity in the mid- and late growth stages. Under higher N conditions, NEAs had higher root oxidation activity and root active absorbing surface area for N uptake and yield formation owing to higher abscisic acid and cytokinin content in the mid- and late growth stages, which improved the seed setting rate, thereby increasing the rice grain yield. These results suggest that NEAs can optimize the morphophysiological characteristics of roots through phytohormone regulation to adapt to different nutrient conditions, thereby promoting N accumulation and yield formation in rice.

Early-Stage Phenotyping of Root Traits Provides Insights into the Drought Tolerance Level of Soybean Cultivars

Soybean (Glycine max (L.) Merr.) may contribute to the agro-ecological transition of cropping systems in Europe, but its productivity is severely affected by summer drought. New drought-avoidance cropping strategies, such as early sowing, require cultivars with high early plant growth under suboptimal conditions. This study aims at phenotyping early-stage root and shoot traits of 10 cultivars commonly grown in Europe. Cultivars were grown in minirhizotrons under two soil moisture status in controlled conditions. Root and shoot traits were evaluated at 10 days after sowing. Field early growth of two cultivars was also analyzed under early and conventional sowing dates. A significant intraspecific variability (p < 0.05) was found for most investigated shoot and root morpho-physiological traits regardless of the soil moisture status under controlled conditions. However, no significant difference among cultivars (p > 0.05) was found in terms of root architectural traits that were mainly affected by water stress. Total root length was positively correlated with shoot length and shoot dry matter (p < 0.05). Under field conditions, the differences between cultivars were expressed by the canopy cover at emergence, which determines the subsequent canopy cover dynamics. The significant early growth difference among cultivars was not related to the maturity group. Cultivars characterized by high root depth and length, high root density and narrow root angle could be considered as good candidates to cope with water stress via better soil exploration. New agronomic strategies mobilizing the diversity of cultivars could thus be tested to improve soybean water use efficiency in response to climate change.

Effects of Soil Types and Irrigation Modes on Rice Root Morphophysiological Traits and Grain Quality

Soil moisture plays an important role in rice (Oryza sativa L.) root development and grain quality. However, little is known about the effects of soil type on rice root morphophysiological traits (RMTs) and grain quality under different irrigation modes. A soil-grown experiment was conducted during the 2016–2017 rice growing seasons in Yangzhou city with three soil types, namely, clay soil, loamy soil, and sandy soil, and three irrigation regimes, namely, conventional irrigation (CI, 0 kPa), alternate wetting and moderate drying (AWMD, −15 kPa), and alternate wetting and severe drying (AWSD, −25 kPa). The AWMD regime improved the RMT by 3.05–48.95% when compared with the CI and AWSD regimes, and the RMTs in loamy were 7.38–93.67% higher than those in clay and sandy soil under AWMD across 2016 and 2017. The AWMD regime improved the rice milling quality and appearance quality both in clay and loamy soil by 2.88–10.08% and 15.43–45.77%, respectively. The CI regime improved the processing quality and nutritional quality of rice in sandy soil. Both loamy and clay soils improved the rice RMTs and grain quality under an AWMD regime. The RMTs were very significantly correlated with water use efficiency, rice milling, and cooking quality and were negatively correlated with rice appearance quality. The AWMD regime can affect the rice RMT and can improve the rice grain quality in loamy soil. Our results provide a theoretical basis for the design of water-saving rice irrigation regimes and for an improvement in rice grain quality in the process of rice cultivation.

Pyridoxal 5′-phosphate enhances the growth and morpho-physiological characteristics of rice cultivars by mitigating the ethylene accumulation under salinity stress

Salinity-induced ethylene accumulation caused by high production of 1-aminocyclopropane-1-carboxylic acid (ACC) hinders rice plant growth and development. Nevertheless, ACC deaminase may alleviate salt stress and high ethylene production in rice cultivars under salinity stress. Pyridoxal 5′-phosphate (PLP), an ACC deaminase co-factor, could be a useful ACC inhibitor in plants; however, it has not been studied before. In the present study, the effects of PLP on the growth and morphophysiological characteristics of rice cultivars (Jinyuan 85 (JY85) and Nipponbare (NPBA) were investigated under salinity stress (control (CK), low salinity (LS), and high salinity (HS) in hydroponic conditions. The experiment was laid out in a completely randomized design (CRD) under factorial arrangement of treatments. The results showed that, compared with no PLP, exogenous application of PLP significantly inhibited ACC and ethylene production in the roots, leaves and panicles of both cultivars under salinity, and PLP was more effective at improving the physiological characteristics of both cultivars under salinity stress. Further, root morphophysiological traits and pollen viability were triggered in the PLP treatment compared to the no-PLP treatment under various salinity levels. ACC production inhibited by PLP was useful for improving the 1000-grain weight, grain yield per plant, and total plant biomass under the CK, LS and HS treatments in both rice cultivars. These results revealed that PLP, as an ACC deaminase cofactor, is a key tool for mitigating ethylene-induced effects under salinity stress and for enhancing the agronomic and morphophysiological traits of rice under saline conditions.

Agronomic and physiological performance of indica/japonica hybrid rice cultivar under low nitrogen conditions

It is generally believed that indica/japonica hybrid rice (IJHR) cultivars have a higher yield potential under high nitrogen (N) supply, but it is not established whether IJHR could obtain a relatively high yield under low N conditions. In order to fill this gap of knowledge, six rice cultivars were examined in this study, consisting of three IJHR cultivars and three japonica hybrid rice (JHR) cultivars, all of which are prevalent in the lower Yangtze River plain. These cultivars were compared for grain yield and other closely-related agronomic and physiological traits under two N input treatments: one being a low application of N (LN) and the other a normal application of N (NN), in 2016 and 2017 in Hangzhou, Zhejiang Province, China. Compared to JHR, IJHR showed grain yield increases of 15% under NN and 25% under LN. Relative to JHR, there are four main agronomic and physiological traits which are associated with IJHR’s superior yield performance under LN conditions. Firstly, IJHR has less redundant vegetative growth, evidenced by a higher percentage of productive tillers. Secondly, IJHR has the larger sink size, resulting from higher spikelet numbers per panicle and sufficient panicles per m2. Thirdly, IJHR exhibited increased shoot activity during the grain filling period, indicated by an increased accumulation of non-structural carbohydrate (NSC) in the stems at heading time, a higher percentage of NSC remobilization from stem to grains during the ripening period, higher enzyme activity in the grains’ sucrose-to-starch conversion process, and greater photosynthesis production during the ripening period. Finally, IJHR was seen to have improved root morpho-physiological traits, characterized by greater root biomass, deeper soil distribution at heading time, and higher root oxidation activity (ROA) during the ripening period. Our results suggest that IJHR’s improved agronomic and physiological traits will lead to improved yields under low N input conditions.

Evaluating rice for salinity using pot-culture provides a systematic tolerance assessment at the seedling stage

BackgroundRice (Oryza sativa L.) is one of the major staple food crops consumed globally. However, rice production is severely affected by high salinity levels, particularly at the seedling stage. A good solution would be the development of an efficient screening methodology to identify genotypes possessing genes for salt tolerance.ResultA new salinity tolerance screening technique using rice seedlings in pot-culture was tested. This method controls soil heterogeneity by using pure sand as a growth medium and minimizes unexpected extreme weather conditions with a movable shelter. Seventy-four rice genotypes were screened at three salinity treatments including high salt stress (electrical conductivity (EC) 12 dSm− 1), moderate salt stress (EC 6 dSm− 1), and control (no salt stress), imposed 1 week after emergence. Several shoot and root morpho-physiological traits were measured at 37 days after sowing. A wide range of variability was observed among genotypes for measured traits with root traits being identified as the best descriptors for tolerance to salt stress conditions. Salt stress response indices (SSRI) were used to classify the 74 rice genotypes; 7 genotypes (9.46%) were identified as salt sensitive, 27 (36.48%) each as low and moderately salt tolerant, and 13 (17.57%) as highly salt tolerant. Genotypes FED 473 and IR85427 were identified as the most salt tolerant and salt sensitive, respectively. These results were further confirmed by principal component analysis (PCA) for accuracy and reliability.ConclusionAlthough tolerant genotypes still need to be confirmed in field studies and tolerance mechanisms identified at the molecular level, information gained from this study could help rice breeders and other scientists to accelerate breeding by selecting appropriate donor parents, progenies and potential genotypes at early growth stages necessary for salinity tolerance research.

Assessing the performance of different irrigation systems on lettuce (Lactuca sativa L.) in the greenhouse.

Lettuce (Lactuca sativa L.) is a very important leafy vegetable in China and is commonly grown using furrow irrigation. In order to improve production efficiency, greenhouse experiments were conducted at Experimental Station, China Agricultural University, Beijing, China using furrow irrigation (FI), micro-sprinkler irrigation (MS), plastic film mulching irrigation (PF) and a combined plastic film mulching–micro-sprinkler irrigation system (PF+MS) to study their effects on soil physical characteristics, water distribution, root morpho-physiological traits, nutrition absorption, lettuce yield and water use efficiency for a spring crop and autumn crop in 2015 (Fig 1). Root length, root surface area, and root density were significantly higher under PF and PF+MS than under FI. Moreover, these traits were higher under MS than under FI but these differences were not significant. The soluble protein, soluble sugar, and Vitamin C content of lettuce decreased in the order PF+MS > PF > MS > FI in both crops. In the spring crop, the biological yield of MS, PF, and PF+MS was 7.22%、36.77%、43.20% higher than FI, respectively. In the spring crop, biological water use efficiency (BWUE) of FI, MS, PF and PF+MS was 20.93, 25.24, 36.81 and 38.54 kg m−3, respectively. The BWUE of MS, PF, and PF+MS was 20.59%, 75.87% and 84.14% higher than FI. Economic water use efficiency (EWUE) of FI, MS, PF and PF+MS was 17.06, 21.31, 31.11 and 32.31 kg m−3, respectively. The EWUE of MS, PF, and PF+MS was 24.91%, 82.36% and 89.39% higher than FI, respectively. The autumn crop achieved a higher WUE than the spring crop. The results suggested that the combined plastic film mulching-micro-sprinkler irrigation was the most suitable irrigation approach for increasing lettuce yield.

The effect of integrative crop management on root growth and methane emission of paddy rice

In previous studies, integrative crop management (ICM) improved shoot growth and grain yield of rice (Oryza sativa L.). However, little is known about the effect of ICM on root growth and methane (CH4) emission of paddy rice. In this study, two rice varieties, Wuyunjing 24 and Yongyou 2640, were grown. A field experiment was conducted with three crop management treatments including zero nitrogen fertilization (0N), local farmer practice (LFP), and ICM. Root morphophysiological traits and CH4 emission from the paddy field were investigated. ICM significantly increased mean grain yield by 29.9%, with the effect attributed mainly to an increase in mean total number of spikelets by 26.4% compared to LFP. ICM increased root and shoot biomass, root length, number of roots, root oxidation activity (ROA), root bleeding rate, and root total and active absorbing surface area by respectively 24.4%, 25.7%, 17.1%, 9.3%, 18.7%, 29.5%, 12.1%, and 24.7%. The concentrations of malic, succinic, and acetic acids in root exudates were respectively 5.8%, 6.0%, and 10.5% higher in ICM than in LFP. Compared to LFP, ICM significantly decreased the rate of CH4 emission during emission peak stages and reduced total CH4 emission by 17.1%. The root morphophysiological traits were positively and significantly correlated with grain yield, whereas root length, specific root length, ROA, and root total and active absorbing surface area were negatively and significantly correlated with total CH4 emission. These results suggest that ICM could achieve the dual goals of increasing grain yield and reducing the greenhouse gas effect by improving the root morphology and physiological traits of paddy rice.

A better root morpho-physiology after heading contributing to yield superiority of japonica/indica hybrid rice

Grain yield superiority of japonica/indica hybrid rice (JIHR) over japonica inbred rice (JIR) and indica hybrid rice (IHR) was reported, and some shoot traits underlying high yield of JIHR were identified, like shoot stay-green traits after heading. To date, little information has focused on root trait differences among JIHR, JIR and IHR. Besides, improved shoot stay-green traits after heading of JIHR might indicate better root morpho-physiological traits after heading compared with JIR and IHR, considering the interdependent relationship between root and shoot. In this study, two JIHR, two JIR, and two IHR were planted in 2014 and 2015 at Ningbo, and in 2015 and 2016 at Yangzhou, China. JIHR showed longer total growth period especially the period from heading to maturity and higher grain yield per day, and 5.6–19.8% higher grain yield compared with JIR and IHR across two years at two sites. JIHR had consistently higher root and shoot biomass at heading and maturity at two sites compared with JIR and IHR. Higher root length and root volume, and more roots in the 11–30 cm soil depth at heading and maturity of JIHR over JIR and IHR were observed across years and sites. JIHR had not only higher leaf SPAD value and leaf photosynthetic rate, but also higher root bleeding rate and root oxidation activity during grain filling, compared with JIR and IHR. JIHR had lower reduction rate of root biomass, length, volume, bleeding rate, and oxidation activity from heading to maturity than JIR and IHR at two sites. Root length and root volume were correlated positively (P < 0.01) to shoot biomass at heading and maturity and rice grain yield. Root bleeding rate and root oxidation activity were correlated positively (P < 0.01) to leaf SPAD value and leaf photosynthetic rate during grain filling and rice grain yield. Our results suggested that better root morpho-physiological traits (showing as longer, larger, deeper, and more active roots) after heading of JIHR could contribute to the shoot stay-green traits, higher biomass accumulation, and finally yield superiority over JIR and IHR.

Shoot and Root Traits Contribute to Drought Resistance in Recombinant Inbred Lines of MD 23-24 × SEA 5 of Common Bean.

Drought is the major abiotic stress factor limiting yield of common bean (Phaseolus vulgaris L.) in smallholder systems in Latin America and eastern and southern Africa; where it is a main source of protein in the daily diet. Identification of shoot and root traits associated with drought resistance contributes to improving the process of designing bean genotypes adapted to drought. Field and greenhouse studies were conducted at the International Center for Tropical Agriculture (CIAT), Palmira, Colombia to determine the relationship between grain yield and different shoot and root traits using a recombinant inbred lines (RILs) population (MD23–24 × SEA 5) of common bean. The main objectives of this study were to identify: (i) specific shoot and root morpho-physiological traits that contribute to improved resistance to drought and that could be useful as selection criteria in breeding beans for drought resistance; and (ii) superior genotypes with desirable shoot and root traits that could serve as parents in breeding programs that are aimed at improving drought resistance. A set of 121 bean genotypes (111 RILs, 2 parents, 8 checks) belonging to the Mesoamerican gene pool and one cowpea variety were evaluated under field conditions with two levels of water supply (irrigated and rainfed) over three seasons. To complement field studies, a greenhouse study was conducted using plastic cylinders with soil inserted into PVC pipes, to determine the relationship between grain yield obtained under field conditions with different root traits measured under greenhouse conditions. Resistance to drought stress was positively associated with a deeper and vigorous root system, better shoot growth, and superior mobilization of photosynthates to pod and seed production. The drought resistant lines differed in their root characteristics, some of them with a vigorous and deeper root system while others with a moderate to shallow root system. Among the shoot traits measured, pod harvest index, and seed number per area could serve as useful selection criteria for assessing sink strength and for genetic improvement of drought resistance in common bean.

Reprint of “Morphological and physiological traits of roots and their relationships with water productivity in water-saving and drought-resistant rice”

Water-saving and drought-resistant rice (WDR) could substantially reduce irrigation water and meanwhile produce higher grain yield compared with paddy rice under water-saving irrigation. The mechanism underlain, however, is yet to be understood. We investigated if improved root traits would contribute to an increase in water productivity in WDR. Two rice varieties, each for WDR and paddy rice, were field-grown with two irrigation methods, continuous flooding (CF) and alternate wetting and drying (AWD) irrigation, which were imposed during the whole growing season. Under CF, grain yield, water productivity (grain yield over amount irrigation water and precipitation) and root morpho-physiological traits, such as root biomass and root oxidation activity (ROA), showed no significant difference between WDR and paddy rice. Under AWD, however, WDR exhibited greater root dry weight, root length density, ROA, total absorbing surface area and active absorbing surface area of roots, greater zeatin (Z)+zeatin riboside (ZR) contents in both roots and leaves, and higher activities of enzymes involved in sucrose-to-starch conversion in grains during grain filing, in relative to paddy rice. Grain yield under AWD was significantly decreased for paddy rice compared with that under CF, but showed no significant difference for WDR between the two irrigation treatments. The WDR variety increased grain yield by 9.2–13.4% and water productivity by 9.0–13.7% over the paddy rice variety under AWD. The root dry weight was significantly correlated with shoot dry weight, and ROA and root Z+ZR content were significantly correlated with leaf photosynthetic rate, Z+ZR content in leaves and activities of key enzymes involved in sucrose-to-starch conversion in grains. Collectively, the data suggest that improved morpho-physiological traits, as showing a greater root biomass, root length density, ROA and root Z+ZR content, contributes to higher grain yield and water productivity for WDR under water-saving irrigation.

Morphological and physiological traits of roots and their relationships with water productivity in water-saving and drought-resistant rice

Water-saving and drought-resistant rice (WDR) could substantially reduce irrigation water and meanwhile produce higher grain yield compared with paddy rice under water-saving irrigation. The mechanism underlain, however, is yet to be understood. We investigated if improved root traits would contribute to an increase in water productivity in WDR. Two rice varieties, each for WDR and paddy rice, were field-grown with two irrigation methods, continuous flooding (CF) and alternate wetting and drying (AWD) irrigation, which were imposed during the whole growing season. Under CF, grain yield, water productivity (grain yield over amount irrigation water and precipitation) and root morpho-physiological traits, such as root biomass and root oxidation activity (ROA), showed no significant difference between WDR and paddy rice. Under AWD, however, WDR exhibited greater root dry weight, root length density, ROA, total absorbing surface area and active absorbing surface area of roots, greater zeatin (Z)+zeatin riboside (ZR) contents in both roots and leaves, and higher activities of enzymes involved in sucrose-to-starch conversion in grains during grain filing, in relative to paddy rice. Grain yield under AWD was significantly decreased for paddy rice compared with that under CF, but showed no significant difference for WDR between the two irrigation treatments. The WDR variety increased grain yield by 9.2–13.4% and water productivity by 9.0–13.7% over the paddy rice variety under AWD. The root dry weight was significantly correlated with shoot dry weight, and ROA and root Z+ZR content were significantly correlated with leaf photosynthetic rate, Z+ZR content in leaves and activities of key enzymes involved in sucrose-to-starch conversion in grains. Collectively, the data suggest that improved morpho-physiological traits, as showing a greater root biomass, root length density, ROA and root Z+ZR content, contributes to higher grain yield and water productivity for WDR under water-saving irrigation.

IDENTIFICATION OF RICE MUTANTS (Oryza sativa L.) FOR AGRONOMICAL AND ROOT SYSTEM TRAITS

Mutation techniques are very important tools to study genetic variability, function, action and regulation of genes. Moreover, in plant breeding the root system is traditionally selected in an indirect way. In this paper we propose the use of mutation techniques to directly select mutants affecting root morphophysiological traits for future mapping and cloning of the genes involved. After preliminary tests to identify the best radiation dose, 2,500 and 3,500 seeds from cultivar Taim, indica sub species, were irradiated with doses 200 Gy and 250 Gy, respectively, and grown in a protected area. After harvesting, M2 seeds were dried, stored and plantlets were evaluated in hydroponic culture, aiming to identify potential root mutants. The dose of 200 Gy seems to be associated with increases in number of seminal roots. From 9,737 seeds evaluated we selected 623 putatively root mutants. Moreover, we selected plants with high and low number of seminal roots. Which can be important to evaluate the root effect on plant establishment. The root mutants described will be available to the scientific community through the rice mutation club / FAO / IAEA after their proper confirmation and characterization.