Diel leaf growth of soybean: a novel method to analyze two-dimensional leaf expansion in high temporal resolution based on a marker tracking approach (Martrack Leaf)

Background

We present a novel method for quantitative analysis of dicot leaf expansion at high temporal resolution. Image sequences of growing leaves were assessed using a marker tracking algorithm. An important feature of the method is the attachment of dark beads that serve as artificial landmarks to the leaf margin. The beads are mechanically constricted to the focal plane of a camera. Leaf expansion is approximated by the increase in area of the polygon defined by the centers of mass of the beads surrounding the leaf. Fluctuating illumination conditions often pose serious problems for tracking natural structures of a leaf; this problem is circumvented here by the use of the beads.

Results

The new method has been used to assess leaf growth in environmental situations with different illumination conditions that are typical in agricultural and biological experiments: Constant illumination via fluorescent light tubes in a climate chamber, a mix of natural and artificial illumination in a greenhouse and natural illumination of the situation on typical summer days in the field. Typical features of diel (24h) soybean leaf growth patterns were revealed in all three conditions, thereby demonstrating the general applicability of the method. Algorithms are provided to the entire community interested in using such approaches.

Conclusions

The implementation Martrack Leaf presented here is a robust method to investigate diel leaf growth rhythms both under natural and artificial illumination conditions. It will be beneficial for the further elucidation of genotype x environment x management interactions affecting leaf growth processes.

     

水冷苗床对番茄幼苗生理的影响

 为探明水冷苗床促进番茄幼苗健壮生长的机理，以‘粉都77’番茄为材料，调查了水冷苗 床和常规苗床下番茄幼苗根系形态、养分吸收及生理生化指标。结果表明：水冷苗床提高了幼苗根系的 吸收面积、根系活力（茎流速率和根系呼吸速率）和养分吸收能力。水冷苗床番茄幼苗地上部N、Ca 和 Mg 含量显著高于对照，而根系P、Ca 和Mg 含量显著低于对照。根际降温措施不仅提高了番茄幼苗根系 抗氧化能力，也显著提高了幼苗的抗氧化能力。水冷苗床作为一种新的根际降温方式，可以缓解夏季高 气温对番茄幼苗生长的不利影响。     

Interactions between root-zone temperature and light levels on growth,development and photosynthesis of Lycopersicon esculentum Mill. cultivar ‘Vendor’

Six-week-old tomato plants were subjected to 5 root-zone temperatures, ranging from 12 to 36°C, and 4 light levels in a factorial design. Large increases in shoot dry weight, leaf area and fruit development resulted from soil warming to 24°C when plants were grown under high light conditions. Shoot growth and fruit weight were reduced at 24°C root temperature under low light conditions. Total plant photosynthesis, leaf area index, net assimilation rates and leaf chlorophyll content were related to plant growth and flower development for the various treatments. Our experiments have shown an interaction between root-zone temperature and light levels for greenhouse tomatoes. Soil warming caused large increases in shoot dry weight and fruit development when light was not limiting plant growth, but had deleterious effects on flowering and fruit set under shaded conditions.     

绒毛白蜡根区局部盐胁迫对其生长的影响

绒毛白蜡（Fraxinus velutina）是滨海盐渍区主要的植被和园林绿化乔木,其发达的根系易受土壤盐分异质性的影响。为探索局部盐胁迫对其生长的影响,采用分根培养桶对幼苗进行局部盐胁迫处理,分析幼苗的生长特征、光合特性、根系分布和离子积累。结果表明,局部低盐胁迫处理的幼苗生长量显著高于均匀盐胁迫和局部高盐胁迫处理;虽然局部高盐胁迫对叶片的水势无影响,但是显著降低了叶片的气孔导度、光合速率和蒸腾速率。局部盐胁迫处理中,无盐胁迫区的根系生物量显著高于盐胁迫区;与均匀盐胁迫相比,局部盐胁迫能够显著降低叶片中Na+的含量,增加K+/Na+。虽然绒毛白蜡的生长在局部盐胁迫条件下受到抑制,且局部盐分越高抑制越强,但生长量与均匀盐胁迫相比显著增高。在局部盐胁迫条件下,细根在无胁迫区的补偿性生长能够提供叶片所需水分,降低叶片中Na+的积累,增加K+含量,缓解了盐胁迫的不利影响。     

根系限制对酿酒葡萄生长发育的影响

 用10、20 和50 L 容积的塑料盆盆栽酿酒葡萄, 探讨了根系生长范围对地上和地下部生长的影响。各处理的根干物量由小到大依次为: 10、20、50 L。50 L 处理根量分别是20L 和10 L 的1. 78 倍和3. 38 倍。按直径将根分为粗根( > 3 mm) 、中级根(0. 5 ～3. 0 mm) 、细根( < 0. 5 mm) , 限根处理使细根量显著增加。同级根平均根长和根重无显著差别, 表明限根后根重减少是根数量减少之故, 而非根变短变细。地上部生长受限根处理影响显著, 干物量、叶质量、叶面积均显著降低。     

Nutritional and cultural factors affecting rooting of papaya (Carica papaya L.) in vitro

Summary

Experiments were conducted to optimize nutritional and cultural requirements for initiation and growth of roots on papaya in vitro. Axillary shoots were obtained from plants which had been sub-cultured monthly for two years. Root initiation was enhanced when 1 to 2 mm of stem base was removed and shoots were growing actively before transfer to the rooting medium. Decreasing daylength during incubation from 24 h to 12 h promoted root initiation. Within the day temperature range of 22 to 29°C, optimum rooting occurred at 27°C and higher temperatures produced higher mean root weights per shoot. High concentrations of growth factors and the absence of sucrose in the medium both reduced root initiation, however, varying the concentration of sucrose and removing growth factors affected mean root weight per shoot. All media contained a modified de Fossard et al. (1974) basal medium plus 10 μM IBA.     

The effect of temperature on growth and development of cultivars of radish under winter conditions

Leaf and root growth and development of 7 early radish cultivars and strains were studied at a series of constant temperatures varying from 10°C to 26°C under winter conditions. Maximum leaf growth was observed at 23°C, maximum root growth initially at 14°C and later on at 10°C. Total dry matter production was highest at 23°C. Between the cultivars/strains distinct differences in rate of leaf and root growth were noted, but no clear interactions of temperature X cultivar/strain were found. The prospects of shortening the growing-period in winter of early radish by means of regulating environmental factors and plant breeding are discussed.     

Einfluss rezenter Klimaveränderungen auf die Phänologie bei Kernobst am Standort Klein-Altendorf – anhand 50-jähriger Aufzeichnungen

This project examines the effects of climate change on pome fruit phenology at Klein-Altendorf in the Rhineland fruit-growing region in the West of Germany, using 50 years of weather data and phenology records, including beginning of flowering (F1), full bloom (F2), harvest date and leaf drop of apple and pear, with the following results:

1. Fifty years of weather records and pome phenology data showed a distinct separation between a first phase (1958–1987), which was 0.42°C cooler, and a second phase (1988–2007), which was 0.66°C warmer than the long-term, 50 year temperature average of 9.4°C, indicating the start of the climate change in 1988.
2. Annual average temperatures rose from 8.8°C to 10.2°C, i.e. by 1.4°C over 50 years at Klein-Altendorf, which affected the apple phenology. A comparison of the second phase (average temp. 10.1°C) with the first phase (9.0°C) resulted in a temperature rise of 1.1°C; the temperature rise in the winter (1.2°C) was greater (by 0.2°C) than in the summer (1.0°C). This temperature rise in the last 20 years (second phase, 1988–2007) was more pronounced in the winter months January ( $ + $ 1.7°C) and February ( $ + $ 1.8°C) than in the spring months March and May both with $ + $ 1.4°C leading to enhanced early post-bloom fruit drop, and July ( $ + $ 1.3°C) and August ( $ + $ 1.6°C).
3. Annual precipitation remained constant at ca. 600?mm with an increase in February, March and April and an equivalent decrease in May (?10?mm) and July (?7?mm) during fruit development.
4. Soil temperatures increased by 2.6°C and hence greater than the air temperature ( $ + $ 1.45°C) over the last 50 years; this increase was most pronounced between January and March.
5. Minimum air temperatures increased also by 2.6°C from ?6.1°C in March 1958 to ?3.5°C in March 2007. The more advanced flowering, brought about by warmer January to March temperatures, now coincides with late spring frosts, thereby maintaining the risk of yield loss due to spring frost in April, a month when the minimum temperature still continues to drop.
6. On average, apple and pear flowering was 10 days earlier without extension of the flowering period after warm winters and appeared more severely affected than the harvest period (3–9 days) and leaf drop (2–3 days earlier) with distinct varietal differences. The apple flowering period was 4 days shorter in the last 10 years and reduced from 12–15 days to 8–10 days. Early maturing cultivars (cvs) ripened 3–4 days earlier, while late cvs ripened 8–12 days earlier. The period between harvest and leaf drop was extended by 2–7 (apple) to 11 days (pear), which requires regional differentiation according to the respective climatic zone and may be beneficial for nutrient translocation into the perennial woody parts of the tree.
7. Since the changes in the temperature-based vegetation period did not explain the effects of climate change on pome phenology, a `pomological vegetation interval' between the beginning of flowering and beginning of leaf drop was defined and was extended by climate change in spring by 0–10 days in apple and by 8 days in pear. Based on flowering (F1, F2) advances, the Meckenheim fruit-growing region was more strongly affected by the climate change compared with other European fruit growing regions.

     

砂土1/4根域施用有机肥对苹果幼树生长的影响

以2 a生有机玻璃箱栽植的分根苹果幼树为材料,研究1/4根域施用不同水平有机肥对苹果幼树新梢和根系生长的影响。结果表明,6月中旬以后,10%和30%有机肥处理的新梢二次生长旺盛;20%有机肥处理春梢段节数、占总新梢节数比例、叶面积、比叶重和春梢生长量均显著大于10%和30%处理,10%有机肥处理秋梢长度、节数、叶面积和比叶重均显著大于20%处理,秋梢补偿生长旺盛;不同比例有机肥处理调控梢类组成,10%和30%处理的长梢比例分别占总新梢22.2%和25.0%,而20%处理的仅占11.8%;除6月份外,20%有机肥处理根系总长度在果树整个生长季节内均显著大于10%和30%处理。砂性土壤局部施用适量有机肥可以调控新梢生长和根系的发育,为果园土壤局部改良、集中营养供应等提供理论依据。     

Use of ex vitro composite plants to study the interaction of cowpea (Vigna unguiculata L.) with the root parasitic angiosperm Striga gesnerioides

Background

Cowpea (Vigna unguiculata L.) is an important grain and forage legume grown throughout sub-Saharan Africa primarily by subsistence farmers on poor, drought prone soils. Genetic improvement of the crop is being actively pursued and numerous functional genomics studies are underway aimed at characterizing gene controlling key agronomic characteristics for disease and pest resistances. Unfortunately, similar to other legumes, efficient plant transformation technology is a rate-limiting step in analysis of gene function in cowpea.

Results

Here we describe an optimized protocol for the rapid generation of transformed hairy roots on ex vitro composite plants of cowpea using Agrobacterium rhizogenes. We further demonstrate the applicability of cowpea composite plants to study gene expression involved in the resistance response of the plant roots to attack by the root parasitic weed, Striga gesnerioides. The utility of the new system and critical parameters of the method are described and discussed herein.

Conclusions

Cowpea composite plants offer a rapid alternative to methods requiring stable transformation and whole plant regeneration for studying gene expression in resistance or susceptibility responses to parasitic weeds. Their use can likely be readily adapted to look at the effects of both ectopic gene overexpression as well as gene knockdown of root associated defense responses and to the study of a broader range of root associated physiological and aphysiological processes including root growth and differentiation as well as interactions with other root pests, parasites, and symbionts.     

Root damage affects nitrogen uptake and growth of young Fuji/M.26 apple trees

Summary

Effects of root damage during the transplant process on growth and nitrogen (N) uptake were studied with one-year-old bench-grafted Malus domestica Borkh ‘Fuji’ on M.26 rootstock apple nursery plants. Plants were potted after grafting and grown outside for one season. At the end of the season uniform trees were selected and randomly divided into four groups. One group of plants were moved into a 2°C cold room with soil and container intact (IR Treatment). Plants in other groups were removed from pots and stored as bareroot in the same cold room for three months. In the spring, bareroot plants were either: (1) transplanted with about 10% of the root system damaged during transplant (TP Treatment and Control-CK); or (2) root pruned by 25% (by volume) prior to transplant (RP treatment). Five trees from each treatment received 1 g of ¹⁵NH₄¹⁵NO₃ at 12, 41 and 76 d after repotting. Control (CK) trees received no N. Trees were harvested 10 d after each N application, and plant growth and total N and ¹⁵N content of different tissues were determined. Root pruning reduced plant total biomass and root biomass at the first two harvests, but the plants from the RP treatment had highest total plant biomass and root biomass at the third harvest. There was no significant difference in the new stem and leaf growth among IR, RP and CK treatments at harvests but the TP treatment reduced new shoot biomass. Plants with intact roots (IR) had the higher total N content while control plants (CK) had the lowest. Root pruning reduced ¹⁵N uptake rate at the first two harvests but promoted it at the third harvest. Our results suggest that plant growth and nutrient uptake was suppressed by root pruning/damage during transplanting only in the early season, and the negative effects on growth and N uptake were offset later in the season by compensative root regeneration.     

RADIX: rhizoslide platform allowing high throughput digital image analysis of root system expansion

Background

Phenotyping of genotype-by-environment interactions in the root-zone is of major importance for crop improvement as the spatial distribution of a plant’s root system is crucial for a plant to access water and nutrient resources of the soil. However, so far it is unclear to what extent genetic variations in root system responses to spatially varying soil resources can be utilized for breeding applications. Among others, one limiting factor is the absence of phenotyping platforms allowing the analysis of such interactions.

Results

We developed a system that is able to (a) monitor root and shoot growth synchronously, (b) investigate their dynamic responses and (c) analyse the effect of heterogeneous N distribution to parts of the root system in a split-nutrient setup with a throughput (200 individual maize plants at once) sufficient for mapping of quantitative trait loci or for screens of multiple environmental factors. In a test trial, 24 maize genotypes were grown under split nitrogen conditions and the response of shoot and root growth was investigated. An almost double elongation rate of crown and lateral roots was observed under high N for all genotypes. The intensity of genotype-specific responses varied strongly. For example, elongation of crown roots differed almost two times between the fastest and slowest growing genotype. A stronger selective root placement in the high-N compartment was related to an increased shoot development indicating that early vigour might be related to a more intense foraging behaviour.

Conclusion

To our knowledge, RADIX is the only system currently existing which allows studying the differential response of crown roots to split-nutrient application to quantify foraging behaviour in genome mapping or selection experiments. In doing so, changes in root and shoot development and the connection to plant performance can be investigated.

     

Root and shoot growth of newly-transplanted apple trees as affected by rootstock cultivar,defoliation and time after transplanting

Summary

An experiment with Malus demonstrated that a large proportion of the transplanted root system was lost through death and decomposition soon after transplanting in the open ground. Mortality of the roots was not influenced by the rootstock cultivars or by defoliation but increased significantly with time. In the first month, shoots of maiden trees of Malus transplanted in June when in-leaf grew, but roots did not. Subsequently, most of the new roots on the rootstock M.9 regenerated from the rootstock stem, whereas with MM.106 the old coarse roots (>2.0 mm diameter) initially present at planting were most important. Root growth occurred in concert with shoot growth such that a functional balance was maintained as shown by the existence of a constant root length:leaf area ratio over a large part of the growing season. Following transplanting, the trees appear to re-establish their optimal ‘functional’ ratio by way of a co-ordinating pattern of growth tending to correct any disturbance to the ratio resulting from transplanting. Defoliation in the early establishment phase caused only a temporary initial reduction in the root growth, but reduced all the shoot growth variables measured and increased the root length:leaf area ratio throughout the growing season.     

砖槽限根对寒富苹果幼树养分分配及枝类构成的影响

通过不同容积砖槽,研究了限根对寒富苹果幼树养分分配及枝类构成的影响。结果表明:总干物质量随根域空间减小而下降,生长季前期干物质及可溶性糖等养分主要分布于叶片中,落叶期粗根中的分配比例增加。根域空间减小提高了枝干韧皮部的干物质分配及养分的分配比例,而木质部的分配比例降低,使植株生长势减弱,形成短枝比例明显增加,有利于促进果树由营养生长向生殖发育方向转化。     

The effects of root-zone warming on the yield and quality of roses grown in a hydroponic system

Rose cvs Ilona, Mercedes and Sonia, budded onto R. multiflora rootstock, were grown using the nutrient film technique. A root-zone temperature of 25°C was compared with ambient root temperatures at three night-time air temperatures of 18°, 12° and ambient (9°C), and in two other experiments at 18°, 14° and 10°C. Bloom yield and stem length and diameter were recorded for a 22-week winter/spring period and for shorter periods in the following summer. In Experiment 1 Sonia responded to root zone warming (RZW) by giving 44% more blooms and a 26% increase in stem length compared with ambient root temperature. Ilona gave a yield response only at a night temperature of 12°C, but RZW resulted in 22% longer stems. Mercedes gave 22% more blooms from RZW. Plants from Experiment 1 were used for a second year in Experiment 2. Mercedes produced 113% more blooms from RZW, Sonia 61% and Ilona 42%. Stem lengths were all increased by 6-7%. Experiment 3 used first-year plants. The pattern of yield response to RZW was similar to the other experiments. Mercedes gave 61%, Sonia 24% and Ilona 18% more blooms. Ilona showed the largest increase in stem length (24%). RZW increased the amplitude of the growth flushes, but their frequency was unaffected. Yields during the subsequent summer, when temperature differences between RZW and ambient temperatures were small, indicated residual effects of the winter treatments. Sonia (Experiment 1), and Mercedes and Sonia (Experiment 2) gave significantly higher yields from the RZW treatments. There was no evidence for a decrease in yield caused by RZW, only Ilona in Experiment 3 giving a lower yield in the summer.     

Root growth following defruiting improves peach tree water status

Summary

Tree growth and water status throughout the growing season and after fruit removal were studied in container-grown peach trees. Trees with fruit (F) and defruited (DF) trees were sampled destructively at bud break (8 March), 1 month after fruit removal (3 June), at harvest (6 August), and before leaf fall (15 October) to determine the mass of leaves, current season shoots, branches, trunk, and the entire root system. Tree water status was determined from the mid-day stem water potential (SWP) the day before each sampling date. Root growth in DF trees was greater than that observed in F trees, while the above-ground biomass was similar in DF and F trees. DF trees therefore had lower leaf:root biomass ratios than F trees throughout the fruit growing season. Environmental factors did not fully explain the seasonal variations in SWP, but there was a significant correlation between leaf:root biomass ratios and SWP. Reductions in leaf:root biomass ratios were accompanied by increases in SWP and, ultimately, DF trees had higher SWP values than F trees in mid-Summer. Improvements in tree water status following fruit removal can be explained, in part, by additional root growth.     

交替根区灌溉和施氮量对葡萄幼树生长特性的影响

该试验采用盆栽进行。以2年生‘巨峰’葡萄为试材,设置不同灌溉方式(传统双侧滴灌、固定根区滴灌、交替根区滴灌)和施氮水平(0.4、0.8、1.2 g/kg土,依次记为低氮、中氮、高氮),研究根区交替灌溉与不同施氮量对葡萄生长特性的影响。结果表明,灌溉方式与施氮量存在显著的互作效应,在新梢修剪前,新梢长度表现传统双侧滴灌最长(77.22 cm)、交替根区滴灌居中(68.53 cm)、固定根区滴灌最短(64.50 cm)。交替根区滴灌和固定根区滴灌的新梢长度依次比传统双侧滴灌降低11.3%、16.5%;葡萄新梢修剪量依次降低10.8%、21.3%。同一灌溉方式下,随着施氮量的增加,新梢修剪量增加。与传统双侧滴灌相比,交替根区滴灌叶面积略有降低,固定根区滴灌叶面积显著降低,在局部根区滴灌2种方式下,随着施氮量的增加,叶面积均呈上升趋势,中氮和高氮处理差异不显著;在传统双侧滴灌方式下,随着施氮量的增加,叶面积先增加后降低。综合考虑不同水氮耦合处理,交替滴灌与中氮互作能够在减少灌溉量和施氮量的条件下优化树体生长。     

镉胁迫对‘丽春’桃树体中镉积累及根系生长的影响

以水培‘丽春’桃（Prunus persica L.Batsch.）幼苗为试材,研究不同镉浓度（1、2 、4 、8、16、64 mg.L^-1 ）和pH 5.6的条件下,根的生长长度,生长速率以及树体器官、茎组织、根、叶亚细胞结构中镉积累的变化。结果表明,处理2 d后,营养液中镉浓度小于4 mg.L-1时根生长速率较对照显著（P<0.05）增加,表现为促进生长,随处理天数的增加,刺激生长效果减弱。当营养液中镉浓度超过4 mg.L^-1、处理时间超过6 d,根生长速率随镉浓度增加而减少,表现为抑制生长。营养液中镉浓度为64 mg.L^-1时,根系停长。镉在桃树体中的积累量：器官中,根>茎>叶;茎组织中,木质部>韧皮部;根、叶亚细胞中,细胞壁>可溶性部分、细胞核>线粒体;根细胞壁中镉含量显著（P<0.05）高于其它亚细胞组分,这说明细胞壁在抵御桃树受镉胁迫时起到关键性作用。     

Root shoot interactions in passionfruit (Passiflora sp.) under the influence of changing root volumes and soil temperatures

Summary

Passionfruit are grown in the tropics and subtropics where mean monthly soil temperatures at 15 cm range from about 10° to 30°C. The choice of rootstock can also influence production with most industries exploiting either the purple (Passiflora edulis f. edulis) or golden passionfruit (P. edulis tflavicarpa). We examined the relationship between shoot and root growth in purple x golden hybrid E-23 grafted onto golden passionfruit seedlings. Growth was manipulated by varying the volume of the soil available to the roots or temperature of the root zone. Shoot and root growth increased as root zone volume increased from 0.3, 1.4, 4, 12 to 24 1. Shoot weight (W_s) was correlated with root weight (W_R):W_S = 12.697 + 5.272 W_R + 0.195 W_R² (r² = 91%, P<0.001), with the plants allocating a smaller proportion of dry matter to the roots as root weight increased. Differences in shoot growth with pot volume were not due to changes in water or nutrient status. In the temperature experiment, the two critical root zone temperatures at 90% of maximum growth were about 20° and 35° C for vine extension, leaf area, node and leaf production, and 20° and 30°C for flower production. Leaf and stem dry weight were optimal between about 18° and 34°C, while maximum root growth occurred at 38°C. There was a weak relationship between shoot (W_s) and root dry weight (W_R): W_s = ?19.346 + 24.500 W_R ?1.046 W_R² (r² = 53%, .P<0.001). Apparently, variations in shoot growth at different soil temperatures cannot be explained solely by differences in root growth. Reduced growth at 10°C was associated with lower chlorophyll concentration, stomatal conductance and net CO₂ assimilation, but not lower leaf water potential. The concentration of most nutrients were lower at 10°C than at higher temperatures, but none was outside the range which would be expected to restrict growth. There appears to be a co-ordination of shoot and root growth as the soil volume available for root growth increases, whereas root temperature affects the roots and tops differently. The results of the pot volume experiment demonstrate the importance of rootstock vigour in passionfruit breeding. Productivity would be affected in cool subtropical areas with soil <20°C and in tropical areas with soil >30°C.