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1.
Three near-isogenic lines (NILs) of Oryza sativa subsp. indica cv. IR64 (Dro1-NIL, Sta1-NIL, Dro1+Sta1-NIL) with DEEPER ROOTING 1 (DRO1), a novel gene for steeper root growth angle, and/or with Stele Transversal Area 1 (Sta1), a QTL for wider stele area, were tested under flooded lowland (FL), alternate wetting and drying lowland (AWD), and rainfed upland (UP) conditions in 2013 and 2014 to compare the effects of DRO1 and Sta1 on yield across different water management regimes. Genotypic variation and water management effects were significant for grain yield, aboveground biomass, and harvest index, as well as their interactions with year, but no significant genotype × water interaction was detected. Dro1-NIL had 14% higher yield than that of IR64 across the three water conditions due to higher harvest index, aboveground biomass, leaf area index, and number of grains. Sta1 tended to reduce the carbon isotope composition (δ13C), leading to a higher harvest index of Sta1-NIL than that of IR64, but grain yield was not increased. Dro1+Sta1-NIL had the highest fraction of intercepted radiation, cumulative radiation interception, and panicle number, with a small but insignificant yield improvement over IR64, but the combination of DRO1 and Sta1 did not surpass the increment from the effects of DRO1 alone. AWD in the more rainy year 2014 attained both higher water productivity and higher biomass, with significant water by year interaction for water productivity. Genotypic variation in water productivity was related with higher leaf area index and fraction interception, with Dro1-NIL larger than in IR64 and Sta1-NIL.  相似文献   

2.
ABSTRACT

The root system architecture (RSA) has been reported to be determined by several root traits such as branching, elongation, and growth angle. This study aimed to evaluate the genotypic variation of plasticity in RSA in response to different soil water distributions in a soil profile. IR64 (shallow root system), YTH183 (adapted to rainfed lowland conditions due to high plasticity in root elongation), and Kinandang Patong (KP – deep root system) were grown in PVC root boxes for 34 days under continuously waterlogged conditions and with soil moisture fluctuations (SMF). For SMF, watering was done from the top of the root box (TI-SMF) or from the bottom of the root box (BI-SMF). A water gradient was observed more clearly in BI-SMF than in TI-SMF, while mean soil moisture content in the root box was kept at around 23% (v/v) after first irrigation in both SMF treatments. RSA changed drastically with SMF in all cultivars, all of which tended to shift root distribution to deeper soil layers in response to SMF. Such changes in RSA resulted from different degrees of plasticity exhibited mainly in nodal root and L-type lateral root development. YTH183 showed a greater ability to change its root growth angle and thus its root distribution in the deeper soil layer compared to IR64 and KP under SMF, indicating that YTH183 could help to improve RSA in cultivars adapted to SMF.  相似文献   

3.
Plant root architecture offers the potential for increasing soil water accessibility, particularly under water-limited conditions. The objectives of this study were to evaluate the root architecture in two genotypes of sorghum (Sorghum bicolor (L.) Moench) differing in root angles and to assess the influence of different deficit irrigation regimes on root architecture. The response of two sorghum genotypes, ‘Early Hegari-Sart’ (EH; steep root angle) and ‘Bk7’ (shallow root angle) to four irrigation treatments was investigated in two replicated outdoor studies using large pots. The results indicated that EH possessed steeper brace and crown root angles, fewer brace roots, greater root biomass, and root length density than Bk7 at deeper soil depths (i.e., 15–30 and 30–45 cm) compared with a shallower depth (i.e., 0–15 cm). Across the soil profile, EH had greater root length density and length of roots of small diameter (<1 mm) than Bk7. Accordingly, EH showed more rapid soil-water capture than Bk7. Different levels of irrigation input greatly affected root architecture. Severe deficit irrigation (25% of full crop transpiration throughout the season) increased the angle and number of crown roots, root biomass, and root length density compared with 75 and 100% of full crop transpiration treatments. Consequently, root system architecture can be effectively manipulated through both genotypic selection and irrigation management to ensure optimal performance under different levels of soil available water.  相似文献   

4.
Deeper rooting 1(Dro1) and Deeper rooting 2(Dro2) are the QTLs that contribute considerably to root growth angle assisting in deeper rooting of rice plant. In the present study, a set of 348 genotypes were shortlisted from rice germplasm based on root angle study. Screening results of the germplasm lines under drought stress identified 25 drought tolerant donor lines based on leaf rolling, leaf drying, spikelet fertility and single plant yield. A panel containing 101 genotypes was constituted based on screening results and genotyped using Dro1 and Dro2 markers. Structure software categorized the genotypes into four sub-populations with different fixation index values for root growth angle. The clustering analysis and principal coordinate analysis could differentiate the genotypes with or without deeper rooting trait. The dendrogram constructed based on the molecular screening for deep rooting QTLs showed clear distinction between the rainfed upland cultivars and irrigated genotypes. Eleven genotypes, namely Dular, Tepiboro, Surjamukhi, Bamawpyan, N22, Dinorado, Karni, Kusuma, Bowdel, Lalsankari and Laxmikajal, possessed both the QTLs, whereas 67 genotypes possessed only Dro1. The average angle of Dro positive genotypes ranged from 82.7° to 89.7°. These genotypes possessing the deeper rooting QTLs can be taken as donor lines to be used in marker-assisted breeding programs.  相似文献   

5.
The purpose of this study was to determine the effect of soil compaction on the herbage yield and root growth of lucerne ( Medicago sativa L.). A field experiment was conducted on a silty loam Mollic Fluvisols soil in 2003–2006. Herbage yield and root morphology, in terms of root length density, mean root diameter, specific root length and distribution of dry matter (DM) in roots, were measured. Four compaction treatments were applied three times annually by tractor using the following number of passes: control without experimental traffic, two passes, four passes and six passes. The tractor traffic changed the physical properties of the soil by increasing bulk density and penetration resistance. Soil compaction also improved its water retention properties. These changes were associated with changes in root morphology and distribution of the DM in roots. Soil compaction resulted in higher proportions of the DM in roots, especially in the upper, 0–10 cm, soil horizon. Decreases in the root length density were observed in a root diameter range of 0·1–1·0 mm. It was also found that roots in a more compacted soil were significantly thicker. An effect of the root system of lucerne on soil compaction was observed. The root system of lucerne decreased the effects of soil compaction that had been recorded in the first and the second year of the experiment. An increase in the number of passes resulted in a decrease in the DM yield of herbage in the second and third harvests each year.  相似文献   

6.
Nitrate () leaching is an environmental and health concern. In grazed pasture systems, leaching primarily occurs beneath animal urine patch areas due to high nitrogen (N) loading and the inability of pasture plants to capture all of this N. This study investigated the relative importance of plant growth and root architecture to recover soil N. Herbage N recovery, dry matter (DM) yield and root architecture, following injections of 15N‐enriched urea at different soil depths (5, 25 and 45 cm), were measured for Italian ryegrass (Lolium multiflorum Lam.) and tall fescue (Festuca arundinacea Schreb.) grown in soil monolith lysimeters (18 cm diameter × 70 cm depth) under simulated South Island, New Zealand winter temperature and light levels. Total herbage N uptake and DM yield were on average 24 and 48% greater in L. multiflorum than F. arundinacea respectively. Root length density (cm cm?3 soil) in the 5‐ to 25‐cm‐depth horizon was similar between species. In the 25‐ to 45‐cm‐depth horizon, F. arundinacea roots were found at higher densities than L. multiflorum. In the 45‐ to 65‐cm‐depth horizon, root length density was fourfold to ninefold higher for F. arundinacea than L. multiflorum, but N uptake efficiency was greater in L. multiflorum (0·48 mg 15N m?1 root) than F. arundinacea (0·09 mg 15N m?1 root). The results suggest that deep F. arundinacea roots are relatively inactive during the winter period and confirm that plant growth is more important than root architecture (e.g. deep roots) to recover soil N and ultimately reduce nitrate leaching losses.  相似文献   

7.
《Plant Production Science》2013,16(4):242-247
Summary

Penetration of the roots deep into soil layer (deep roots) may alleviate growth inhibition under various soil stress conditions. In this study, the nodes from which deep roots had emerged were examined at the heading stage in rice and maize grown in a 2 m long tube. The effect of soil mechanical stress on the rooting nodes of deep roots was also examined. The roots that emerged in a relatively early growth stage, that is, the roots from coleoptilar, 1st and 2nd node in rice, and the seminal root and roots from the coleoptilar, 1st and 2nd nodes in maize, penetrated into the deep soil layer. The node which produced the highest number of deep roots was the 1st node in rice and the coleoptilar node in maize. Seminal root of rice and seminal adventitious roots of maize did not penetrate into the deep soil layer although they emerged at an early growth stage. In the rice root system, the nodal roots, emerged from the upper portion of the node, tended to penetrate deeper than the nodal roots emerged from the lower portion of the same node. Soil compaction did not affect these tendencies.  相似文献   

8.
《Plant Production Science》2013,16(5):553-562
Abstract

The difference in rooting pattern between two grain sorghum cultivars differing in drought tolerance was investigated under drought stress. The cultivars, Gadambalia (drought-tolerant) and Tabat (droughtsusceptible), were grown in bottomless wooden or acrylic root boxes to examine root parameters. Gadambalia consistently exhibited higher dry matter production and leaf water potential than Tabat under drought stress in both root boxes. In the experiment with wooden root boxes, under a drought condition, Gadambalia extracted more water from deep soil layers (1.1-1.5 m), which was estimated from the reduction in soil water content, than Tabat. This was because Gadambalia had a significantly higher root length density in these soil layers. The high root length density was due to enhanced lateral root development in Gadambalia. In the other experiment with acrylic root boxes, though total root length in the upper soil layer (0-0.5 m) was declined by limited irrigation in both cultivars, the reduction in Gadambalia was moderate compared with that in Tabat owing to the maintenance of fine root growth. Unlike Tabat, Gadambalia had an ability to produce the nodal roots from higher internodes even under drought, which resulted in the high nodal root length of Gadambalia. The growth angle of nodal roots was significantly correlated with root diameter, and the nodal roots from the higher internodes had large diameters and penetrated into the soil more vertically. These results indicate that the responses of roots (i.e. branching and/or growth of lateral root, and nodal root emergence from higher internodes) to soil dryness could be associated with the drought tolerance of Gadambalia.  相似文献   

9.
In this study, to identify deep rooting accessions, we assessed the differences in root depth based on the length of the longest primary root among 586 different rice accessions: 511 Oryza sativa and 75 O. glaberrima. Malagkit Pirurutong and Binicol were identified as the two rice accessions with deepest roots through four field experiments conducted at two different locations in West Africa. For these two accessions, root depths reached 35.6 and 41.4 cm, respectively, in the first experiment at Bamako; on the other hand, their depths only reached 22.6 and 18.6 cm, respectively, in the second and third experiments at Ibadan, leading to inconsistent genotypic ranking based on root depth between the two locations. However, Malagkit Pirurutong was identified as deep rooting in both locations; in addition, it showed deep rooting in the fourth experiment in a 20-mm irrigation treatment, even when compared with the deep rooting reference Azucena. Nonetheless, this pattern was not found under a 10-mm irrigation treatment. Malagkit Pirurutong kept developing deep roots even following 60 days after sowing (DAS), whereas other shallower rooting accessions ceased deepening by 60 DAS. The longer period for deepening roots would be beneficial for terminal drought stress.  相似文献   

10.
To identify differences in root plasticity patterns of two upland New Rice for Africa (NERICA) varieties, NERICA 1 and 4, in response to drought under conditions with contrasting soil profile characteristics, soil moisture gradients were imposed using a sloping bed system with depths ranging 30–65 cm and a line-source sprinkler system with a uniformly shallow soil layer of 20 cm depth. Varietal differences in shoot and root growths were identified only under moderate drought conditions, 11–18% v/v soil moisture content. Further, under moderate drought soil conditions where roots could penetrate into the deep soil layer, deep root development was greater in NERICA 4 than in NERICA 1, which contributed to maintaining dry matter production. However, under soil conditions with underground impediment to deep root development, higher shoot dry weight was noted for NERICA 1 than for NERICA 4 at 11–18% v/v soil moisture content, which was attributed to increased lateral root development in the shallow soil layer in NERICA 1. Enhanced lateral root development in the 0–20-cm soil layer was identified in NERICA 1 even under soil conditions without an impediment to deep root development; however, this did not contribute to maintaining dry matter production in upland rice. Thus, we show different root developmental traits associated with drought avoidance in the two NERICA varieties, and that desirable root traits for upland rice cultivation vary depending on the target soil environment, such as the distribution of soil moisture and root penetration resistance.  相似文献   

11.
Genotypic variation in patterns of root distribution, nitrate interception and response to moisture stress were assessed in both parents and 198 progeny of a perennial ryegrass (Lolium perenne L.) full‐sibling mapping population. This was carried out in metre‐deep tubes of sand culture in a glasshouse experiment. The proportion of root dry matter (DM) weight in the top 10 cm of sand ranged from 0·33 to 0·75 and values of log10(1 ? K), where K is the constant for an exponential model relating root DM weight and root depth, also showed wide variation among genotypes. The proportion of a pulse of 15N recovered in whole plants ranged from 0·124 to 0·431. There was a positive linear correlation between the proportion of 15N recovered and plant total DM weight, but no relationship between nitrate interception and patterns of distribution of DM weight of roots. Some genotypes responded to moisture stress by increasing root growth, and in others root growth was inhibited. It is concluded that this below‐ground variability in root variables may be an evolutionary adaptation by plant populations to survive heterogeneity in soil biotic and edaphic factors.  相似文献   

12.
《Plant Production Science》2013,16(3):281-288
Abstract

Deep penetration of an axile root is one of the important factors that allow crops to form deep root systems. In this study, the nodes from which the deepest penetrated roots had emerged were examined at the heading stage in upland rice and maize grown in large root boxes and in the field. Both experiments were designed to measure the direction, length, and rooting nodes of each root. In maize, the growth angles of axile roots increased with vertical elongation as rooting nodes acropetally advanced. The roots that emerged from the lower nodes, namely from coleoptilar to the second node, exhibited conspicuously horizontal elongation in the field, reaching 2.3 m in width at the maximum. The roots that emerged from higher than the fifth node were too short to penetrate deeply. Thus, these roots became the deepest root in less or no probability under field conditions. On the other hand, the fourth nodal root, which had an intermediate growth angle and length, had the highest probability. In upland rice, the deepest roots emerged from the nodes lower than the forth node on the main stem in the root boxes. In the field, however, the deepest roots emerged at later stages, that is, the roots from the middle nodes on the main stem and from the low nodes on the primary and secondary tillers were the deepest roots. Five out of nine of the deepest roots were from the prophyll nodes in three field-grown upland rice. The deepest roots from the same plant were estimated to have emerged and grown at approximately the same stage.  相似文献   

13.

Background

Plant root systems play a major role in anchoring and in water and nutrient uptake from the soil. The root cone angle is an important parameter of the root system architecture because, combined with root depth, it helps to determine the volume of soil explored by the plant. Two genes, DRO1 and SOR1, and several QTLs for root cone angle have been discovered in the last 5 years.

Results

To find other QTLs linked to root cone angle, a genome-wide association mapping study was conducted on two panels of 162 indica and 169 japonica rice accessions genotyped with two sets of SNP markers (genotyping-by-sequencing set with approximately 16,000 markers and high-density-rice-array set with approximately 300,000 markers). The root cone angle of all accessions was measured using a screen protractor on images taken after 1 month of plant growth in the Rhizoscope phenotyping system. The distribution of the root cone angle in the indica panel was Gaussian, but several accessions of the japonica panel (all the bulus from Indonesia and three temperate japonicas from Nepal or India) appeared as outliers with a very wide root cone angle. The data were submitted to association mapping using a mixed model with control of structure and kinship. A total of 15 QTLs for the indica panel and 40 QTLs for the japonica panel were detected. Genes underlying these QTLs (+/?50 kb from the significant markers) were analyzed. We focused our analysis on auxin-related genes, kinases, and genes involved in root developmental processes and identified 8 particularly interesting genes.

Conclusions

The present study identifies new sources of wide root cone angle in rice, proposes ways to bypass some drawbacks of association mapping to further understand the genetics of the trait and identifies candidate genes deserving further investigation.
  相似文献   

14.
Much of commercial potato production in Florida is irrigated using sub-surface seepage irrigation. A perched water table is maintained during the season within 50 cm below the top of the potato ridge. Fertilizer placement is critical in this system to maximize plant uptake and to minimize leaching potential. Optimal placement of fertilizers is dependent on root distribution. The objectives of this study were to develop and test a new methodology to spatially describe potato root distribution as affected by nitrogen rate and irrigation system. Soil slices containing representative samples of the potato root system at full flowering were taken from plots fertilized with ammonium nitrate at 168, 224, and 280 kg N ha?1. The proposed sampling methodology performed satisfactorily. Root length density (cm root cm?3 soil) and specific root length (cm root mg?1 root dry weight) were not affected by nitrogen rate, but were affected by spatial position in the soil profile. The highest root length density value (0.72 average) was observed within 12 to 15 cm of the seedpiece. Low root length density values averaging 0.036 were observed between 24 and 36 cm from the top of the ridge. Specific root length values indicated a relatively homogeneous root system in terms of the quantity of invested biomass by unit of root length except in the two central units below 24 cm from the top of the ridge where thickened roots caused significant lower values averaging 6.47 as compared with the average of 15.87 from the surrounding Units in the slice. Root thickening in deep apical roots suggested aerenchyma formation promoted by a combination of saturated soil conditions in the root zone caused by inappropriate irrigation management and soil compaction. Fertilizer placement under the seedpiece should be a good alternative to increase potato nitrogen uptake under seepage irrigation.  相似文献   

15.
通过云南典型的红壤坡耕地对土壤实施深松+旋耕 15 cm（SRT）、深松+免耕（SNT）、深松+翻耕 20 cm（SP1）、深松+翻耕30 cm（SP2）、旋耕15 cm（RT）、免耕（NT）、翻耕20 cm（P1）和翻耕30 cm（P2）8种耕作方式,研究对玉米的根系根条数、根直径、入土角度、根幅、生物量及根系抗拔力等的影响。结果表明,深松+翻耕20 cm处理能增加玉米根条数、根系入土角度和10 cm土层处根系生长幅度,增大根系生物量,尤其是深层土壤（20～30 cm）根系生物量,同时对玉米产量也具有提高作用。深松+翻耕30 cm处理能增大根系的垂直抗拔力。因此,土壤通过深耕处理能改善玉米根系构型和分布,进而增强玉米根系抗倒伏能力。  相似文献   

16.
ABSTRACT

This study evaluated the effect of three N fertilization levels 60 (low), 120 (medium), and 180 (high) kg N ha?1 and soil moisture content gradients created by a line-source sprinkler on the expression of plasticity in lateral root branching and dry matter production (DMP) of upland new rice for Africa (NERICA) 1 and 4. There were no significant differences in DMP between NERICA 1 and 4 under well-watered, mild drought, and severe drought conditions regardless of N level. In contrast, under moderate drought (12–21% v/v of soil moisture content [SMC] in 2011 and 16–24% v/v of SMC in 2012), NERICA 1 had significantly higher shoot dry weight, total root length (TRL), lateral root length, and branching index than NERICA 4 at medium and high N; however, there was no significant difference between the two NERICAs in DMP at low N. TRL of NERICA 1 was significantly higher under moderate drought than well-watered conditions, but only with medium and high N. Regardless of N level, moderate drought did not enhance NERICA 4’s root system. Thus, NERICA 1’s root system exhibited plastic development, promoting lateral root branching at medium and high N. These morphological changes were associated with the greater DMP in NERICA 1 than NERICA 4 under moderate drought, whereas the lack of such plasticity at low N meant genotypic differences in DMP were obscured. Our findings implied that N application can improve upland NERICA productivity under moderate drought conditions, but differences in variety and field conditions may influence efficacy.  相似文献   

17.
田间条件下水稻根系分布及其与土壤容重的关系   总被引：23，自引：2，他引：23  
 采用大田和筒栽方法研究了超高产三系杂交稻协优9308和两系杂交稻两优培九在穗分化期和开花期根系生长和分布及土壤容重对根系分布的影响。结果表明，在田间条件下，土层15 cm内水稻根系占根系总量的89%～98%，深层根系丛间比丛中比例高。不早衰的协优9308根系生长量较两优培九大。土壤容重提高，根系总生长量下降，且深层根系的量和比例下降。就深耕法对水稻根系生长和分布的影响进行了讨论。  相似文献   

18.
Temperate pasture legumes (e.g. Trifolium and Medicago spp.) often have a higher phosphorus (P) requirement for maximum productivity than pasture grasses. This is partly attributed to differences between legumes and grasses in their ability to acquire P from soil. We are the first to report differences in root morphology traits important for soil P acquisition in a range of novel pasture legumes being developed for use in temperate pastures of southern Australia. Up to a 3·6‐fold range in specific root length (SRL) (79–281 m root g?1 root) and 6·1‐fold range in root hair length (RHL) (0·12–0·75 mm) was found between the pasture species. The commonly used Trifolium subterraneum and Medicago sativa had relatively low SRLs and short root hairs, while Ornithopus compressus, O. sativus and Biserrula pelecinus had RHLs and SRLs more similar to those of two grass species that were also assessed. Specific root length was highly correlated with average root diameter, and root traits were relatively stable at different plant ages. We surmise that large differences among pasture legume species in the effective volume of soil explored could translate into significant differences in their critical P requirements (i.e. soil P concentration to achieve 90% of maximum shoot yield).  相似文献   

19.
K. Iwama 《Potato Research》2008,51(3-4):333-353
Potato roots are concentrated mostly in the plow layer up to 30 cm in soil depth. Some roots extend up to 100 cm depth and the total root length throughout the soil profile reaches about 10–20 km m?2 area. There are large differences in root mass (dry weight and length) in the plow layer between cultivars, breeding lines and wild relatives. The differences are generally stable across different environmental conditions, such as locations with different soil types, fertilizer rates and planting densities. Under favourable environmental conditions without severe shortage of water and nutrients, root mass differences between genotypes are related to maturity class: late genotypes continue root growth longer, and attain larger root mass and deeper rooting than early genotypes. Differences in root mass become clear at the start of flowering, much earlier than differences in shoot mass. Root mass is negatively correlated with early tuber bulking. However, root mass generally shows positive correlations with shoot mass and final tuber yield. Differences in root mass also exist amongst genotypes of the same maturity class. Using root mass in the plow layer and tuber yield as selection criteria, Konyu cultivars were bred in Japan. They showed significantly less reduction of leaf conductance and photosynthesis, leaf area and tuber yield than commercial cultivars under dry soil conditions. To assist breeding for root characters, new methods have been developed to assess the ability of roots to penetrate into hard soil layers using pots with paraffin-vaseline discs and the ability to absorb under low water potential in vitro. Physiological research on root characteristics contributed in the past, and will continue to do so in the future, to the development of new cultivars with high drought tolerance and to the improvement of irrigation practice.  相似文献   

20.
A sulphur (S)‐deficient top soil was used in a pot experiment to investigate the effect of S supply on shoot and root growth and development in alfalfa (Medicago sativa L.). The treatments consisted of three rates of addition of S: 0, 20 and 40 mg kg?1 soil and each was replicated four times. Alfalfa was harvested at 15, 30, 45, 60 and 75 d after seedling emergence. By the end of the experiment, plants with S supply had a significantly larger leaf area, heavier leaf, shoot and root dry weight per pot than controls. The effects of adding S also significantly increased plant height, basal stem diameter, chlorophyll concentration of young leaves, root length and root surface area compared with controls. The effects of S were greater on shoots than on roots. The ratio of root to shoot dry weight was 0·47 when S was supplied and 0·88 without added S, indicating that c. 0·32 and 0·47 of the total net photosynthate, produced with or without S supply, respectively, were used for the development of roots. Overall, overcoming S deficiency resulted in a significant increase in shoot and root growth.  相似文献   

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