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1.
Application of phosphorus (P) fertilizer is an important factor for improving the tolerance to water deficit in many plants. A pot experiment was conducted to identify the effects of P application on soybean adaptability to water deficit at the R1 (initial flowering) and R4 (full pod) stages through the investigation of root morphological traits, plant P uptake and resultant yield in two soybean (Glycine max L. Merrill) cultivars (Dongnong 46 and Heisheng 101). The four levels of P application were 0, 7.3, 14.6 and 29.2 mg kg?2, respectively. The three water treatments were (1) 65–75% of field water capacity (FWC) as a well-watered control, (2) 30–40% of FWC at the R1 stage, and (3) 30–40% of FWC at the R4 stage. Root traits, plant uptake of P and yield were significantly reduced by water deficiency at different growth stages, especially at the R4 stage. Application of P enabled to alleviate the adverse effects of water deficit, to increase the root dry weight, root length and root surface area, and to slow root senescence after the R5 (initial pod filling) stage. The response of soybean genotypes to both water and P deficit was different. In the absence of P application, Dongnong 46 showed relatively low adaptability to water deficit at the R4 stage, whereas Heisheng 101 showed a lower reduction of root traits and yield. The beneficial effects of P application for Dongnong 46 were more pronounced than those for Heisheng 101. Based on this experiment, we suggested that P fertilizer application to soybean may be justified in low-rainfall years because of its ability to enhance the soybean adaptability to water deficit stress by improving the root morphology, P uptake and consequently yield.  相似文献   

2.
Application of phosphorus (P) fertilizer is an important factor for improving the tolerance to water deficit in many plants. A pot experiment was conducted to identify the effects of P application on soybean adaptability to water deficit at the R1 (initial flowering) and R4 (full pod) stages through the investigation of root morphological traits, plant P uptake and resultant yield in two soybean ( Glycine max L. Merrill) cultivars (Dongnong 46 and Heisheng 101). The four levels of P application were 0, 7.3, 14.6 and 29.2 mg kg−2, respectively. The three water treatments were (1) 65–75% of field water capacity (FWC) as a well-watered control, (2) 30–40% of FWC at the R1 stage, and (3) 30–40% of FWC at the R4 stage. Root traits, plant uptake of P and yield were significantly reduced by water deficiency at different growth stages, especially at the R4 stage. Application of P enabled to alleviate the adverse effects of water deficit, to increase the root dry weight, root length and root surface area, and to slow root senescence after the R5 (initial pod filling) stage. The response of soybean genotypes to both water and P deficit was different. In the absence of P application, Dongnong 46 showed relatively low adaptability to water deficit at the R4 stage, whereas Heisheng 101 showed a lower reduction of root traits and yield. The beneficial effects of P application for Dongnong 46 were more pronounced than those for Heisheng 101. Based on this experiment, we suggested that P fertilizer application to soybean may be justified in low-rainfall years because of its ability to enhance the soybean adaptability to water deficit stress by improving the root morphology, P uptake and consequently yield.  相似文献   

3.
ABSTRACT

Phosphorus (P) efficiency (shoot dry weight at low P/shoot dry weight at high P) of a cultivar is the ability to produce a high yield in a soil that is limited in that element for a standard genotype. The large variation in P efficiency of different crops provides opportunities for screening crop species that perform well on low phosphorus soil. To explain the differences in P efficiency of sunflower (Helianthus annuus L.) cultivars a glasshouse pot experiment was conducted by using P-deficient soil [0.5 M sodium bicarbonate (NaHCO3)-extractable P 8.54 mg kg?1] treated with 0 (low P) and 100 mg P kg?1 soil (high P). The relationship between P efficiency and P, calcium (Ca), iron (Fe), zinc (Zn), and manganese (Mn) nutrition and anthocyanin accumulation was investigated in ten sunflower cultivars. Phosphorus deficiency resulted in significant decreases in the shoot and root yield. Phosphorus-efficient cultivars have the ability to produce higher yield than the inefficient cultivars in a limited P conditions. Our results showed that P-efficient cultivars had lower P concentrations, but higher P content in low P conditions. Phosphorus-efficient cultivars also have lower Ca and Fe concentrations in low P conditions but not in P-sufficient conditions. Applied P resulted in significant decreases in Zn concentrations in the shoots of the cultivars. Anthocyanin concentrations showed an accumulating pattern in all cultivars under P deficiency. The results demonstrated that phosphorus efficiency of the sunflower cultivars depends on their ability to produce higher yield and take up more P, and lower the concentration of Ca and Fe in shoots under low P conditions.  相似文献   

4.
Primary determinants of crop production in arid/semiarid regions are lack of moisture and infertility, especially phosphorus (P) deficiency or unavailability. The effects of P and water stress (WS) levels on shoot and root dry matter (DM), leaf area, root volume, total root length, and shoot and root P concentrations and contents were determined in two bean [Phaseolus acutifolius Gray, cv ‘Tepary #21’ ("drought‐resistant") and P. vulgaris L., cv “Emerson’ ("drought‐sensitive")] and two sorghum [Sorghum bicolor (L.) Moench, cv SA7078 ("drought‐resistant") and ‘Redlan’ ("drought‐sensitive")] cultivars grown in nutrient solution. Plants were grown with different levels of P (20 and 100 μM for bean and 20, 80, and 160 μM for sorghum) when seedlings were transferred to nutrient solution, and WS levels of 0, 13.8, and 1 6.4% polyethylene glycol (PEG‐8000) introduced after plants had grown in solution 23 days (bean) and 31 days (sorghum). All growth traits were lower when bean and sorghum plants were grown with WS and low P. Growth traits were higher in cultivars grown with high compared to low P regardless of WS. Root P concentration and content and shoot content, but not shoot P concentration, were lower when bean plants were grown with WS compared to without WS. Tepary #21 bean had higher shoot DM, leaf area, total root length, and shoot P concentration than Emerson when plants were grown with WS at each level of P. Sorghum shoot and root P concentrations were higher as P level increased regardless of WS, and WS had little effect on shoot P concentration, but root P concentration was higher. Contents of P were similar for SA7078 and Redlan regardless of P or WS treatment, but SA7078 had greater P contents than Redlan over all P and WS treatments. “Drought‐resistant”; cultivars generally had better growth traits, especially total and specific root lengths, than “drought‐sensitive”; cultivars.  相似文献   

5.
不同供磷水平下水稻磷素吸收利用和产量的基因型差异   总被引：13，自引：1，他引：13  
通过田间试验研究了不同供磷水平对8个水稻品种磷素吸收利用和稻谷产量的影响。研究结果表明,两种供磷水平下,水稻的稻谷产量、磷利用效率和各生育期地上部磷积累都存在显著的基因型差异。低磷胁迫显著降低水稻的稻谷产量和各生育期地上部磷积累,显著提高水稻的磷利用效率。相关性分析表明,低磷胁迫下水稻稻谷产量与水稻磷利用效率、生育前期(秧苗期+分蘖期)地上部磷积累以及生育中期(抽穗期)地上部磷积累呈显著正相关(p<0. 05);正常供磷条件下水稻稻谷产量与磷利用效率、生育前期地上部磷积累呈显著正相关(p<0. 05)。因此筛选和培育具有较高磷利用效率和在生育前期具有较强磷素积累特性的水稻基因型可能是缓解南方水稻土磷素严重缺乏的有效途径之一。  相似文献   

6.
In an attempt to evaluate whether breeding and selection for high yielding capacity changed the P requirement of modem wheat cultivars. the response of two wheat cultivars to different levels of P supply was investigated. A traditional cultivar (‘Peragis’) and a modern spring-wheat cultivar (‘Cosir’) were cultivated in a C-loess low in available P and high in CaCO3 in 120 cm high PVC tubes. In addition and for comparison, nutrient solution experiments were also conducted. Shoot growth, root growth. P uptake. P translocation and P distribution within the shoot at different developmental stages were compared. The grain yield of the modern cultivar ‘Cosir’ was higher at limiting and non-limiting P supply and. therefore, this cultivar can be considered as more P-efficient than the traditional cultivar. Grain yield reduction at low P supply was mainly due to an inhibition of tillering and thus lower number of ears per plant, whereas the number of grains per ear was hardly affected. Reduced tillering at low P supply could not be related to P concentrations in the shoot meristematic tissues which were generally much higher than in other plant tissues and kept at an elevated level even at limiting P supply. Root branching (1st order laterals) was reduced at limiting P supply in ‘Cosir’ but not in ‘Peragis’ which, generally, had lower numbers of laterals at the beginning of tillering. From the results it can be concluded that the main factors contributing to the higher P efficiency of the modern cultivar ‘Cosir’ are (i) efficient use of assimilates for root-growth characteristics which enhance P acquisition: enhanced root branching and thus smaller mean root diameter and longer root hairs, (ii) an efficient P uptake system, (iii) efficient remobilization of P from vegetative plant organs to the grains, and most importantly (iv) lower P requirement for grain yield formation because of lower ear number per plant but higher grain number per ear.  相似文献   

7.
ABSTRACT

Our earlier study demonstrated that the landrace of Japonica rice, Akamai exhibits low-P (phosphorous) tolerance mechanisms compared to the conventional type cultivar, Koshihikari. The present study examined the genotypic difference of yield, plasticity of root growth, and internal utilization of acquired P (allocation pattern of biomass and P among different vegetative and reproductive organs) of two contrasting cultivars in response to P-deficiency. Each cultivar was grown until maturity with (+P) and without (–P) P supply in pots (two plants per pot) filled with 15 kg of Regosol soil. Grain yield and yield components were determined along with biomass and P accumulation in different vegetative and reproductive organs. To assess the plasticity of root growth, the soil column in the pot was divided into two equal portions (upper and lower soil layers) in which the root dry weight and length were measured separately. Among the investigated yield components, the number of filled grains per panicle was the key parameter determining genotypic differences of grain yield of two cultivars. P-deficiency had a marked influence on grain filling of Koshihikari where the filled grain percentage under –P condition was reduced by 29% compared to that under +P condition. However, the respective reduction for Akamai was only 11%. Low-P tolerance ability of Akamai imparts a yield advantage over Koshihikari under P-deficient conditions because of the production of the higher number of filled grains per panicle. Akamai explored both upper and lower soil layers of the pot more efficiently in search of P through greater root biomass and length. Akamai grown under P-deficient conditions had remarkably lower P concentrations in less active vegetative tissues (partly and fully senesced leaves) than those of Koshihikari; whereas, more active organs (green leaves and panicles) contained a greater amount of P. Akamai’s higher plasticity to external P availability can be a genetic resource for developing low-P tolerant, high-yielding rice genotypes suitable for predicted future P-limited environments.  相似文献   

8.
To evaluate the response of some selected wheat cultivars to silicon application at different growth stages under drought stress, an experiment was carried out in the greenhouse of College of Agriculture, Shiraz University, Iran, during 2012 using a completely randomized factorial design with four replications. Experimental treatments included drought stress (100% F.C. as control and 40% F.C. as drought) and foliar application of 6 mM sodium silicate (control, application at mid tillering stage, at anthesis stage, and application at tillering + anthesis stages) and wheat cultivars (Sirvan and Chamran, relatively drought-tolerant, and Shiraz and Marvdasht, drought-sensitive cultivars). Drought stress significantly reduced chlorophyll content, leaf area, relative water content, grains per spike, 1000-grain weight, grain yield and biomass of all wheat cultivars. Furthermore, drought stress increased electrolyte leakage of the flag leaves of all cultivars. In contrast, foliar-applied silicon significantly increased these parameters and reduced electrolyte leakage. Furthermore, highest positive influence of silicon application was observed at combined use of silicon both at the tillering + anthesis stages in wheat plants under both stress and non-stress conditions. Significant differences were found in physiological responses among wheat cultivars. The drought tolerant cultivars (Sirvan and Chamran) had significantly higher growth and yield than those of drought sensitive cvs. Shiraz and Marvdasht under drought stress. In conclusion, foliar application of silicon especially at the tillering + anthesis stages was very effective in promoting resistance in wheat plants to drought conditions by maintaining cellular membrane integrity and relative water content, and increasing chlorophyll content.  相似文献   

9.
In order to study the effects of salinity and water stress on growth and macronutrients concentration of pomegranate plant leaves, a factorial experiment was conducted based on completely randomized design with 0, 30, and 60 mM of salinity levels of sodium chloride and calcium chloride (1:1) and three irrigation intervals (2, 4, and 6 days) with 3 replications on ‘Rabab’ and ‘Shishegap’ cultivars of pomegranate. The results of the shoot and root analysis indicated that the salinity and drought affected the concentration and distribution of sodium (Na+), potassium (K+), chloride (Cl?), calcium (Ca2+), magnesium (Mg2+), and phosphorus (P+) in pomegranate leaves. Mineral concentrations of sodium (Na+), chloride (Cl-), potassium (K+), in shoots and roots were increased with increasing salinity. Drought treatments increased the concentration of Cl?, Na+, and Mg2+ in the shoot. Both cultivars showed significant differences in the concentrations of elements, however the most accumulation of Na+ and Cl? was observed in ‘Rabab,’ while the ‘Shishegap’ cultivar had the most absorption of K+. ‘Shishegap’ cultivar showed higher tolerance to salinity than ‘Rabab’ through maintaining the vegetative growth and lower chloride transport to the shoot, and improvement of potassium transport to shoot.  相似文献   

10.
ABSTRACT

Considerable variation exists among wheat cultivars for phosphorus (P) acquisition and utilization to produce higher yields. We investigated critical P requirements for optimum grain yield of two wheat cultivars contrasting in P-use efficiency, i.e., NIA-Sunder (P-efficient) and NIA-Saarang (P-inefficient). Grain yield, P accumulation, and other P-efficiency relations of both cultivars increased with progressive addition of P, but at variable rates. NIA-Sunder exhibited higher grain yield, grain P concentration, harvest index, and P-use efficiency at all P levels as compared to NIA-Saarang. Internal P requirement for achieving 95% relative grain yield in NIA-Sunder and NIA-Saarang was obtained when P concentration in their grains was 4.07 and 3.48 mg g?1 recorded at external P levels of 57.2 and 78.1 mg kg?1 soil, respectively. Overall, NIA-Sunder accumulated 15% more grain P and required 27% less external P for attaining 95% relative yield than P-inefficient cultivar. Results suggested that internal and external P requirements aiming at optimum grain yield are associated with genotypic variations in wheat cultivars for P-utilization efficiency.  相似文献   

11.
Genotypic differences in arsenic (As) and cadmium (Cd) uptake and their translocation within rice seedlings grown in solution culture were investigated. Arsenic uptake and its translocation differed significantly between eight cultivars. The largest shoot and root As concentrations were found in cultivar ‘TN1’ and ‘ZYQ8’, while cultivar ‘JX-17’ had the lowest As concentration. Arsenic concentration in shoot or root of ‘JX-17’ was about 50% of that in cultivar ‘ZYQ8’. Specific Arsenic uptake (SAU) was found significantly different between rice cultivars, which was about 2-fold higher of ‘ZYQ8’ than that of ‘JX-17’. The Cd accumulation also differed significantly between cultivars. Rice cultivar ‘JX-17’ had the highest ability in Cd uptake, but the lowest ability in Cd translocation from root to shoot. The transfer factor (TF) of Cd had an important effect on Cd accumulation by rice seedlings. Arsenic can competitively inhibit P uptake by rice seedlings, P concentrations in shoots, or roots treated with As were significantly lower than those without As addition. However, the concentrations of P and As were positively correlated within these genotypes. The Cd immobilization by cell wall was an important mechanism for Cd detoxification. The cell wall bound 21–44% of total Cd in shoots and 25–59% of total Cd in roots of these tested genotypes. The genotypic differences in As and Cd uptake and translocation within rice seedlings provide the possibility of selecting and breeding genotypes and /or cultivars with reduced levels of As and Cd in rice grains.  相似文献   

12.
【目的】 研究镉胁迫下芹菜生长、镉吸收和向上运转品种间差异,为筛选镉低积累型芹菜品种减少镉对人体的危害提供依据。 【方法】 以10个芹菜品种为试材进行基质无土栽培试验,基质为蛭石,营养液采用1/2华南农业大学叶菜类营养液配方,以只浇灌营养液的处理作为对照,浇灌含15 mg/L氯化镉（CdCl2）的营养液为Cd胁迫处理;每3 d浇灌一次,每次浇灌0.2 L,累计浇灌15次,每盆Cd施用量为45 mg。移栽45 d后,测定生长指标与根、叶柄和叶片Cd含量。计算相对生长量（relative growth yield,RGY）和转运系数（translocation factor,TF）,并筛选出高、低Cd积累品种。分别对高、低Cd积累品种进行穴盘基育苗,14 d后采用华南农业大学叶菜类营养液配方进行营养液栽培,21 d后利用非损伤微测技术（non-invasive micro-test technology,NMT）测定根系分生区、伸长区和根毛区Cd2+离子流速。 【结果】 与非Cd胁迫相比,Cd胁迫使‘速生四季西芹王’、文图拉西芹’、‘四季小香芹’、‘实心香芹’、 ‘雪白芹菜’ 地下部受到显著抑制,对地上部无显著影响;Cd胁迫促进了 ‘四季小香芹’ 地上部生长;而 ‘种都金黄芹菜’、‘红芹’、‘鲍芹’ 地上部受到显著抑制,对地下部则无显著影响;‘马家沟芹菜’ 和 ‘速生香芹’ 地上部和地下部均生长均受到抑制。食用器官叶柄中Cd含量以 ‘种都金黄芹菜’ 和 ‘雪白芹菜’ 最高;‘速生香芹’ 和 ‘实心香芹’ 最低。地上部Cd含量高的 ‘种都金黄芹菜’ 和 ‘雪白芹菜’ 对Cd转运能力也最高;Cd含量低的 ‘速生香芹’ 对Cd转运能力也最低。在根系成熟区（根毛区）,‘种都金黄芹菜’ 较 ‘速生香芹’ 有更高Cd2+ 离子流速。 【结论】 Cd胁迫下,芹菜不同品种生长、Cd吸收、转运和积累存在显著差异。‘四季小香芹’、‘速生四季西芹王’、‘文图拉芹菜’、‘实心香芹’ 和 ‘雪白芹菜’ 较为耐镉;而 ‘种都金黄芹菜’、‘红芹’、‘鲍芹’、‘马家沟芹菜’ 和 ‘速生香芹’ 对镉敏感。‘雪白芹菜’ 和 ‘种都金黄芹菜’ 为高Cd积累型,‘实心香芹’ 和 ‘速生香芹’ 为低Cd积累型,其中 ‘实心香芹’ 表现为低Cd含量和高生长量。高Cd积累型芹菜较低Cd积累型芹菜有更强Cd2+ 吸收能力和Cd转运能力,根部Cd2+ 流速可用于低积累品种的快速筛选。   相似文献   

13.
[目的]在干旱和半干旱地区,缺磷常导致作物产量下降.研究不同水分状况下,磷素施用次数对花后小麦旗叶和穗部维持光合效能及胚乳细胞分裂能力的影响,为科学施用磷肥提供理论依据.[方法]以冬小麦品种'新冬23号'和'新冬20号'为试验材料开展裂区田间试验.设干旱胁迫(DT,灌水量为5625 m3/hm2)和适水灌溉(WT,灌水...  相似文献   

14.
ABSTRACT

Drought is a major factor threatening crop production worldwide. Developing wheat varieties that are adapted to drought prone environments is a sustainable strategy to improve wheat production and productivity. The aim of this study was to evaluate and select bread wheat genotypes for yield and yield components, and for stability under drought stress and non-stress conditions. One hundred and twenty genotypes were evaluated at five test sites in the 2018/19 cropping season using a 10 x 12 alpha lattice design with two replicates. The level of drought stress was imposed using different sowing dates (early planting representing non-stressed, while late planting as drought stressed conditions) following the onset of the main rain at each site. Grain yield and yield components were recorded, and drought indices were calculated for each genotype. Among the drought tolerance indices, GMP, MP, HM, STI and YI were found to be the most suitable for predicting drought tolerance because they had significant and positive correlations with yield under drought stress and non-stress conditions. Rank sum analysis identified the most drought tolerant genotypes as ‘YS-34', ‘YS-85' and ‘YS-82’. The selected wheat genotypes are useful genetic resources for future drought tolerance breeding programmes in Ethiopia or similar agro-ecologies.  相似文献   

15.
花后干旱与渍水下氮素供应对小麦碳氮运转的影响   总被引：22，自引：7，他引：22  
防雨池栽条件下，设置渍水、干旱和对照3个土壤水分处理，每个水分处理下再设置两个施氮水平，研究了花后渍水和干旱逆境下氮素水平对两个蛋白质含量不同的小麦品种碳氮运转的影响。结果表明，与对照相比，花后渍水和干旱处理均降低小麦叶、茎鞘、颖壳等各营养器官花前贮藏物质再运转量和再运转率以及营养器官花前贮藏物质总运转量，降低了籽粒重。水分逆境下增施氮肥可以提高小麦叶和颖壳花前贮藏物质再运转量和运转率，茎鞘花前贮藏物质再运转量和运转率。在对照和干旱下增施氮肥提高了营养器官花前贮藏物质总运转量和运转率以及籽粒重和花后同化物输入籽粒量，而渍水下增施氮肥趋势相反。水分逆境降低了小麦叶、茎鞘、颖壳等各营养器官花前贮藏氮素再运转量和再运转率以及花前贮藏氮素总运转量和总运转率，降低了小麦籽粒氮积累量。在对照和干旱下增施氮肥提高了小麦叶片的花前贮藏氮素运转量和运转率，茎鞘的贮藏氮素运转量，营养器官花前贮藏氮素总运转量和运转率，籽粒氮积累量以及花前氮素对籽粒总氮贡献率，而渍水下增施氮肥趋势相反。水分逆境明显降低小麦产量、淀粉和蛋白质产量，且干旱处理下增施氮肥有利于籽粒产量、淀粉产量和蛋白质含量的提高，而渍水下增施氮肥使产量进一步降低。试验结果表明，花后渍水和干旱逆境下施用氮肥可明显调节小麦碳、氮物质运转以及最终的籽粒淀粉与蛋白质积累。  相似文献   

16.
[目的]探究长期干旱胁迫下不同施钾水平对油菜生长、籽粒品质、钾素利用的影响,旨在明确不同钾肥水平下油菜通过调节生长和营养分配应对干旱胁迫的机制,为油菜抗旱栽培提供科学依据.[方法]以抗旱油菜品种油研57和干旱敏感品种川油36为试验材料,采用盆栽土培试验,每盆装风干土10 kg,设置K2O施用量0、80和160 mg/k...  相似文献   

17.

Phosphorus (P) deficiency is one of the most yield limiting factors in crop production in Brazilian Oxisols. A greenhouse experiment was conducted to evaluate 20 upland rice genotypes at low (25 mg P kg?1) and high (200 mg P kg?1) P levels applied to a Brazilian Oxisol. Grain yield and yield components were significantly influenced by P level and genotype treatments. There was a significant interaction between P level and genotype treatments in relation to grain yield, indicating genotypes responded differently under two P levels. Based on grain yield efficiency index (GYEI), genotypes were classified into efficient, moderately efficient and inefficient groups. The efficient genotypes in utilizing P were ‘BRA052053’, ‘BRS Primavera’, ‘BRA052015’, ‘BRA052023’, ‘BRA01506’, ‘BRA052045’, ‘BRA032033’, ‘BRA01596’ and ‘BRA052034’. Remaining genotypes were classified as moderately efficient in P use efficiency. None of the genotypes were fall into inefficient group. Grain yield was significantly and positively related with shoot dry weight, panicle number, grain harvest index, 1000-grain weight and had a negative and significant correlation with spikelet sterility. Grain weight was having maximum contribution in total rice plant weight comparing to root and shoot, indicating improvement in harvest index of modern Brazilian upland rice cultivars by breeding.  相似文献   

18.
Influences of nitrogen (N), phosphorus (P), and potassium (K) fertilizer doses were assessed on iron (Fe) accumulation in leaves and grains of three high-yielding rice cultivars differing in grain Fe concentration. Effects of these treatments were also measured on grain yield, leaf area, and plant biomass of the cultivars. Nitrogen, P, and K applications improved plant biomass and grain yield of all cultivars. Among the nutrients, N was most effective in increasing leaf Fe concentration, followed by P and K in all three rice cultivars. Sharbati accumulated the greatest concentration of leaf Fe followed by IR-64 and Lalat. However, greater doses of these nutrients adversely affected grain yield and Fe content of leaf and grain. Application of excess N, P, and K fertilizers may, thus, sometimes results in lowering of grain Fe content in rice. Judicious application of the elements is recommended for prevention of Fe-induced malnutrition.  相似文献   

19.
Abstract

Plants grown in highly weathered or highly alkaline calcareous soils often experience phosphorus (P) stress but never a P‐free environment. Thus, applications of mineral P fertilizers are often required to achieve maximum yield, but recovery of applied P fertilizers is notoriously low. Phosphorus deprivation elicits a complex array of morphological, physiological, and biochemical adaptations among plant species and genotypes to enhance P acquisition and utilization efficiency. Ten Brassica cultivars were grown hydroponically to investigate their relative efficiency to utilize deficiently (20‐µM) and adequately (200‐µM) supplied P, using Johnson's modified solution. Cultivars differed significantly (P<0.001) in biomass accumulation. Orthophosphate concentration and uptake in shoot and root, absolute and relative growth rate, and P‐utilization efficiency (PUE) were also significantly different among various Brassica cultivars. Root‐shoot ratio and specific absorption rate were substantially increased in plants subjected to low P supply. Shoot and root dry‐matter yield as well as total biomass production correlated significantly (P<0.01) with their total P uptake and PUE. Cultivars, which were efficient in P utilization, were also efficient accumulators of biomass under adequate as well as deficient levels of P supply. As part of the study, kinetic parameters of P uptake were evaluated for six contrasting Brassica cultivars in PUE, grown in nutrient solution. The kinetic parameters related to P influx were maximal transport rate (Vmax), the Michaelis–Menten constant (Km), and the external concentration when net uptake is zero (Cmin). Lower Km and Cmin values were indicative of P‐uptake ability of the cultivars, evidencing their adaptability to P‐stress conditions. In another experiment, six cultivars were exposed to no P nutrition for 27 days after initial feeding on optimum nutrition for 14 days. All the cultivars retranslocated P from aboveground parts to their roots during growth in P‐free conditions, the magnitude of which was variable in different cultivars. Phosphorus concentration at 41 days after transplanting was higher in developing leaves than developed leaves. Translocation of absorbed P from metabolically inactive sites to active sites in plants growing under P‐stress conditions may have helped the tolerant cultivars to establish a better rooting system, which provided basis for tolerance against P‐deficiency stress and increased PUE.  相似文献   

20.
Drought and salinity individually or in combination adversely affects growth, development, and yield of sugarcane. Apart from physiological traits, nutrients status was studied in six commercial hybrids subjected to drought, salinity, and salinity + drought. Drought was simulated by withholding irrigation in the field, while salinity and salinity + drought were imposed in microplots. Physiological traits, viz, chlorophyll fluorescence, chlorophyll (SPAD) index, biomass production, and leaf area index, reduced drastically in combined stress as against individual stress treatments. Among major nutrients, phosphorus (P) reduced significantly in all the stress treatments. Similarly, iron (Fe) and Zinc (Zn) reduced due to stress and showed differential response for growth stages. Reduction in cane yield and sucrose percentage in stress conditions warrants supplementation of P, Fe, and Zn.  相似文献   

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