不同硼效率棉花品种根系参数和伤流液组分的差异

溶液培养条件下研究硼对不同硼效率棉花品种根系参数、伤流量及伤流液组分的影响。结果表明,缺硼抑制棉花根系生长,根重、根体积、根长、活跃吸收面积、总吸收面积、活跃吸收面积占总吸收面积的比例以及伤流量均显著降低,高效品种降低幅度比低效品种小;缺硼还使高效品种根系比表面积升高,而低效品种无显著变化。缺硼显著影响不同棉花品种伤流液各组分含量,与低效品种相比,高效品种伤流液中有较多的NO3-、K+、无机磷、可溶性糖和游离氨基酸。说明缺硼条件下高效品种根系比低效品种具有更强的吸收、代谢活力,可能是其硼效率较高的主要原因之一。     

油菜硼高效的遗传

Field experiments were conducted to study the inheritance of boron efficiency in oilseed rape (Brassica napus L.) by evaluating the boron (B) efficiency coefficient (BEC, the ratio of the seed yield at below the critical boron level to that at the boron-sufficient level) with 657 F_2:3 lines of a population derived from a cross between a B-efficient cultivar, Qingyou 10, and a B-inefficient cultivar, Bakow. Qingyou 10 had high BEC as well as high seed yield at low available soil B. On the contrary, Bakow produced low seed yield at low B status. Boron deficiency decreased the seed yield of the F_2:3 lines to different extents and the distribution of BEC of the population showed a bimodal pattern. When the 657 F_2:3 lines were grouped into B-efficient lines and B-inefficient lines according to their BEC, the ratio of B-efficient lines to B-inefficient lines fitted the expected ratio (3:1), indicating that one major gene controlled the B-efficiency trait. 127 F_2:3 lines selected from the population at random, with distribution of BEC similar to that of the overall population, were used to identify the target region for fine mapping of the boron efficiency gene.     

不同硼效率甘蓝型油菜苗期对硼镁营养的反应

利用溶液培养研究硼低效和高效甘蓝型油菜(Brassica.napus)苗期对硼镁营养的反应。结果表明,低硼浓度下提高镁时,油菜的生长受影响不大,硼含量和累积量降低,镁含量和累积量及叶绿素上升。低镁浓度下提高硼时,油菜镁含量、镁积累量降低,且硼低效品种降低幅度大于硼高效;叶绿素降低幅度则硼高效大于硼低效品种。高硼浓度下提高镁时,硼镁含量和累积量及叶绿素含量均提高,提高幅度为硼高效品种大于低效品种。高镁浓度下提高硼时,硼镁表现出显著的相互促进,硼高效品种促进效应大于低效品种。在很大程度上镁影响油菜叶绿素a的含量,而硼影响油菜叶绿素b的含量。硼镁营养对锌含量无大的影响;在低镁浓度下,油菜低效品种锰含量显著增加。无论是低镁或高镁浓度下提高硼,硼高效和低效品种铁含量均有所增加,低效品种增加显著。     

Identification of Phosphorous Efficient Germplasm in Oilseed Rape

ABSTRACT

Plant species and genotypes within one species may significantly differ in phosphorus (P) uptake and utilization when they suffer from P starvation. The objective of this research was to screen P-efficient germplasm of oilseed rape (Brassica napus L.) and analyze the possible mechanism responsible for P efficiency by two-steps screening experiments and validation of P efficiency. Phosphorus efficiency coefficient at seedling stage, namely, ratio of shoot dry weight under low P to that under adequate P (PECS) of 194 oilseed rape cultivars varied from 0.050 to 0.62 and was significantly related with shoot dry weight under low P level (r = 0.859??, P < 0.01). Oilseed rape cultivar ‘Eyou Changjia’ presented the highest P efficiency coefficient in each growth stage and had the highest seed yield at low P, whereas oilseed rape cultivar ‘B104-2’ was the most sensitive to low P stress among the 12 candidate cultivars obtained from the two-steps screening experiments. Under low P condition in validation experiments of soil and solution cultures, ‘Eyou Changjia’ could produce much more dry matter and acquire more P than ‘B104-2.’ Moreover, P efficient coefficient obtained from the pot experiment was comparable to those from the field experiment. This might be attributed to high P uptake efficiency for ‘Eyou Changjia’ when it suffered from low-P stress. Comparison of results from the hydroponics with those from the pot and field experiments led to the conclusion that the P uptake efficiency in the hydroponics is highly related to that in soil culture conditions. These results show that there are large genotypic differences in response to phosphorus deficiency in oilseed rape germplasm (Brassica napus L.) and ‘Eyou Changjia’ is P-efficient and ‘B104-2’ is P-inefficient. By comparing these results further, the mechanism responsible for P efficiency was suggested to be mainly due to high P uptake efficiency by forming larger root system, and improving the ability of mobilizing and acquiring soil P in P-efficient oilseed rape under the condition of P starvation.     

不同硼效率棉花品种木质部和韧皮部汁液中矿质养分的差异

溶液培养条件下研究硼对2个硼效率不同的棉花品种木质部、韧皮部中硼及其它矿质养分运输的影响。结果表明,缺硼使2个棉花品种木质部汁液硼含量及溢出量明显降低,低效品种降低幅度大于高效品种。供硼充足(0.5mg/L)时,2个棉花品种木质部汁液中硼浓度均小于培养液中硼浓度;缺硼(0.002mg/L)时,高效品种与低效品种木质部汁液硼浓度分别是培养液硼浓度的32.0和20.5倍。缺硼使2个棉花品种木质部汁液中钾、锰、铜、锌含量均升高,高效品种升高幅度较大;钙含量均降低,低效品种降低幅度较大;高效品种镁含量增高,低效品种降低。而2个棉花品种木质部各养分(钾、镁、钙、锰、铜、锌)溢出量均降低,低效品种降低更明显。无论在缺硼或供硼充足时,2个棉花品种韧皮部中硼浓度均极低,但韧皮部溢泌液中其它养分受缺硼影响品种间表现不同,高效品种韧皮部钾、镁、锰、铜溢出量升高,低效品种则降低;2个品种钙、锌溢出量均降低,低效品种降低幅度更大。     

BORON DEFICIENCY IN RAINFED WHEAT IN PAKISTAN: INCIDENCE,SPATIAL VARIABILITY AND MANAGEMENT STRATEGIES

Boron (B) deficiency is potentially an important nutrient constraint in calcareous soils. We determined B deficiency incidence and spatial distribution in rainfed wheat (Triticum aestivum L.) in 1.82 Mha Pothohar plateau in Pakistan, its relationship with soil types, crop responses to B, and internal B requirement and B fertilizer use efficiency of wheat. Plant and soil analyses indicated deficiency in 64% of the 61 sampled fields; geostatistics-aided contour maps delineated B deficient areas. In rainfed field experiments, B use increased wheat yields up to 11%. Fertilizer requirement was 1.2 kg B ha^?1; critical B concentration (mg kg^?1) ranges were: young whole shoots, 4–6; flag leaves, 5–7. Boron uptake by wheat was 0.14–0.58% of applied dosage, leaving substantial residual impact. Highly cost-effective B use or B-efficient genotype adoption can enhance wheat productivity and grower-income. Such effective nutrient assessment and management approaches can be beneficially adopted elsewhere as well.     

Zinc‐boron interaction effects in oilseed rape

The interaction effect of applied zinc (Zn) and boron (B) on early vegetative growth and uptake of Zn and B by two oilseed rape (canola) (Brassica napus L.) genotypes was investigated in a sand culture experiment under controlled environmental conditions. Two genotypes (Yickadee and Dunkeld) were grown at three Zn levels (0.05, 0.25, and 2.0 mg kg^‐1 soil) and two B levels (0.05 mg kg^‐1 soil and 0.5 mg kg^‐1 soil). Dunkeld produced significantly higher shoot and root dry matter than Yickadee at low Zn and low B supply indicating the superiority of Dunkeld over Yickadee for tolerance to both low Zn and low B supply. Chlorophyll content of fresh leaf tissue was increased significantly by an increase in Zn and B supply. Zinc deficiency enhanced B concentration in younger and older leaves. Boron concentration was higher in older leaves than in the younger leaves irrespective of B deficiency and sufficiency indicating immobility of B in two oilseed rape genotypes tested. Zinc concentration was higher in younger leaves than in the older leaves indicating mobility of Zn. An increased supply of Zn enhanced B uptake under high boron supply only. Zinc uptake in Dunkeld was enhanced significantly with an increased rate of B supply under high Zn supply, while the effect was not significant in Yickadee. Dunkeld proved to be more efficient in Zn and B uptake than Yickadee.     

STUDIES ON DIFFERENTIAL RESPONSE OF SPRING CANOLA CULTIVARS TO BORON TOXICITY

Although many states recommend boron (B) fertilizer for many field crops, information about B toxicity of canola is lacking. This experiment was carried out at Central Anatolia, Turkey from 2002 to 2003, to determine genotypic range in B efficiency of eight spring canola cultivars, to identify the B-inefficient cultivars and to identify specific responses. The cultivars were grown under B moderate deficiency (extractable B 0.56 mg kg^?1) and toxic B applied (15 kg B ha^?1) conditions. According to the results, seed yield varied significantly among the cultivars and B application decreased the seed yield by 31% on average. Also, toxic B application reduced protein and oil contents similar to seed yield, and increased leaf B concentration in all varieties. This study has shown that leaf B concentration has increased considerably when B is applied to Pactol and Star cultivars, but seed yield of +B and ?B has not shown significantly a change. It is possible to say that Star and Pactol—which have not been affected by the toxic B application—are genotypes that are tolerant to B toxicity and may be cultivated at B toxic lands.     

Effect of Root Zone Temperature on Oilseed Rape (Brassica napus) Response to Boron

Abstract

Oilseed rape (Brassica napus) is sensitive to low boron (B) supply, and its growth response to B may be influenced by soil temperature. To test the relationship between B and temperature, oilseed rape (cv. Hyola 42) seedlings were grown at 10°C (low) root zone temperature (RZT) with B supply from deficient to adequate B levels until growth of low B plants just began to slow down. Half of the pots were then transferred to 20°C (warm) RZT for 11 days before they were moved back to 10°C RZT for the final 4 days. Both plant dry mass and B uptake increased after plants were exposed to warm RZT. However, plant B deficiency was exacerbated by warm RZT in low B plants because of increased relative growth rate and shoot–root ratio without a commensurate increase in B uptake rate. It is concluded that RZT above the critical threshold for chilling injury in oilseed rape can nevertheless affect the incidence of B deficiency by altering shoot–root ratio and hence the balance between shoot B demand and B uptake.     

Analysis of Genetic Diversity in the Brassica napus L. Gene Pool Using SSR Markers

Genetic diversity throughout the rapeseed (Brassica napus ssp. napus) primary gene pool was examined by obtaining detailed molecular genetic information at simple sequence repeat (SSR) loci for a broad range of winter and spring oilseed, fodder and leaf rape gene bank accessions. The plant material investigated was selected from a preliminary B. napus core collection developed from European gene bank material, and was intended to cover as broadly as possible the diversity present in the species, excluding swedes (B. napus ssp. napobrassica (L.) Hanelt). A set of 96 genotypes was characterised using publicly available mapped SSR markers spread over the B. napus genome. Allelic information from 30 SSR primer combinations amplifying 220 alleles at 51 polymorphic loci provided unique genetic fingerprints for all genotypes. UPGMA clustering enabled identification of four general groups with increasing genetic diversity as follows (1) spring oilseed and fodder; (2) winter oilseed; (3) winter fodder; (4) vegetable genotypes. The most extreme allelic variation was observed in a spring kale from the United Kingdom and a Japanese spring vegetable genotype, and two winter rape accessions from Korea and Japan, respectively. Unexpectedly the next most distinct genotypes were two old winter oilseed varieties from Germany and Ukraine, respectively. A number of other accessions were also found to be genetically distinct from the other material of the same type. The molecular genetic information gained enables the identification of untapped genetic variability for rapeseed breeding and is potentially interesting with respect to increasing heterosis in oilseed rape hybrids.     

Rhizosphere calcareous soil P-extraction at the expense of organic carbon from root-exuded organic acids induced by phosphorus deficiency in several plant species

The amount of organic acids in root exudates rapidly increases under phosphorus (P) deficiency. Loss of carbon from root-exuded organic acids, which are derived from plant net photosynthetic products, is generally considered negligible. The present study aimed to study the characteristics of root-exuded organic acids, extraction of phosphorus (P extraction) in calcareous soil and the expression of organic carbon from root-exuded organic acids in two woody Moraceae plants (Broussonetia papyrifera L. Vent and Morus alba L.) and two herbaceous cruciferous plants (Orychophragmus violaceus L. Schulz and Brassica napus L.) under two P levels (P-normal and P-deficient). P extraction and the amount of root-exuded organic acids simultaneously and disproportionately increased in the four plant species tested under P deficiency. The maximum P-extracting capability of the four plant species was observed after 40 days of treatment. Additionally, the response of root-exuded organic acids induced by P deficiency was species-specific. B. papyrifera extracted more P in calcareous soil, and expended less organic acid for the same P-extraction than M. alba. Similarly, O. violaceus extracted more P in calcareous soil, and consumed less organic acid for the same level of P-extraction than B. napus. Root-exuded oxalic and malic acids accounted for most of the increment of P extraction in woody Moraceae plants, while root-exuded citric acid accounted for most of the increment in P extraction in herbaceous cruciferous plants. B. papyrifera and O. violaceus exhibited the strongest P-extracting capability at lower expense of organic carbon over the treatment duration in the four plant species. O. violaceus had the most rapid response of root-exuded organic acids to P deficiency, while B. napus had the slowest response. Thus, rapid response with low organic carbon cost and high efficiency of extraction on P in calcareous soil may underlie the strong adaptability of B. papyrifera and O. violaceus to a Karst environment.     

Relationships Among <Emphasis Type="Italic">Brassica napus</Emphasis> (L.) Germplasm from Spain and Great Britain as Determined by RAPD Markers

The genetic diversity and the relationships among a collection of Brassica napus L. European populations were evaluated using random amplified polymorphic DNA markers. The study included 33 accessions of B. napus collected from Galicia (northwestern Spain) and 18 British cultivars, 16 accessions of B. napus and two accessions of Brassica oleracea L. used as controls. DNA from 25 individuals per population was analyzed using 18 decamer primers. One hundred thirty-eight amplification products were scored of which 105 were polymorphic. These bands ranged in size from 350 to 2500 base pairs. Similarity coefficients and cluster analysis were computed and six groups were obtained. Cluster I was the largest and included all the landraces from northwestern Spain, except two accessions that grouped separately into Clusters III and IV, respectively. A low level of genetic variability was detected among the B. napus Spanish genotypes, while considerable diversity was present among the British ones, which grouped into three groups, two main clusters and one group formed by one accession. Cluster II included all commercial varieties grown in Great Britain whereas Cluster V grouped local varieties maintained by the growers for many years. Cluster VI was a singularity formed by one entry. British accessions of B. oleracea had the greatest dissimilarity with all the other populations and grouped separately in Clusters VII and VIII. As conclusion, B. napus landraces used in northwestern Spain as leafy-green vegetable probably have an independent origin from B. napus crops grown in other European regions. Besides, separate domestication in northwestern Spain and Great Britain for a different end use might have led to two distinct gene pools.     

SEED YIELD AND YIELD COMPONENTS RESPONSE OF RAPE (B. NAPUS) VERSUS MUSTARD (B. JUNCEA) TO SULFUR AND POTASSIUM FERTILIZER APPLICATION IN NORTHWEST PAKISTAN

Improper sulfur (S) and potassium (K) fertilizer management, particularly with continued soil nutrient mining, is one of the major factors contributing to low seed yield of canola in northwestern Pakistan. A field experiment was conducted in 2007?2008 on a S and K deficient clay loam soil at the Research Farm of NWFP (Northwest Frontier Province) Agricultural University, Peshawar, Pakistan, with an objective to determine seed yield and yield components response of Brassica oilseed rape versus mustard to S and K application. Twenty treatments in a randomized complete block design were consisted of two oilseed rape (B. napus canola) and mustard (B. juncea canola) genotypes at three rates each of S (15, 30, and 45 kg S ha^?1) and K (30, 60, and 90 kg K ha^?1) fertilizers plus one control (no S and K applied). Seed yield and yield components increased significantly with K and S fertilization as compared to the zero-S/zero-K control. Both genotypes responded positively for seed yield and yield components to K and S fertilization, but the magnitude of response varied with levels of S and K, as well as combined K + S applications. It is concluded that a combination of 60 kg K + 30 kg S ha^?1 would improve seed yield and yield components of rape and mustard in the study area and contribute significantly to increased production. Growing B. napus was better than B. juncea in the study area, because B. napus produced significantly higher seed yield and yield components than B. juncea, indicating that yield components are the most important criteria for selection of Brassica genotypes for higher seed yield.     

Responses of Wheat Genotypes to Zinc Fertilization Under Saline Soil Conditions

ABSTRACT

A greenhouse experiment with four bread wheat [Triticum aestivum L.] genotypes, ‘Rushan,’ ‘Kavir,’ ‘Cross,’ and ‘Falat,’ and a durum wheat [Triticum durum L.] genotype, ‘Dur-3,’ at two zinc (Zn) rates (0 and 15 mg Zn kg^?1 dry soil) and four salinity levels (0, 60, 120, and 180 mM NaCl) was conducted. After 45 d of growth, the shoots were harvested, and Zn, iron (Fe), potassium (K), sodium (Na), and cadmium (Cd) concentrations were determined. In the absence of added Zn, visual Zn deficiency symptoms were observed to be more severe in ‘Dur-3’ and ‘Kavir’ than in other genotypes. The effect of Zn deficiency on shoot dry matter was similar to its effect on visual deficiency symptoms, such that shoot growth was most depressed in ‘Kavir’ and ‘Dur-3.’ At the 180 mM treatment, Zn fertilization had no effect on shoot dry matter of genotypes. Genotypes with high Zn efficiency had greater shoot Zn content than genotypes with low Zn efficiency. In the absence of added Zn, the Dur-3, and ‘Cross’ genotypes had the highest and lowest Cd concentrations, respectively. Application of Zn had a positive effect on salt tolerance of plants.     

Response of carboxylate metabolism to zinc deficiency in Lactuca sativa and Brassica oleracea plants

Species or genotypes differ in their zinc use efficiency (ZnUE) under low Zn availability in the soil. Organic acids (OAs) synthetized by plant carboxylate metabolism may play a role in Zn‐deficiency tolerance. The main objective of the present work was to assess the response of two species of great agronomic interest such as Lactuca sativa and Brassica oleracea to Zn deficiency focusing on OAs and carboxylate metabolism. For this, L. sativa and B. oleracea plants were grown in hydroponic culture with two different Zn‐application rates: 10 µM Zn as control and 0.1 µM Zn as deficiency treatment. ZnUE parameters, concentrations of OAs and enzymes of carboxylate metabolism were analyzed. L. sativa showed better Zn uptake efficiency (ZnUpE), while B. oleracea demonstrated better Zn utilization efficiency (ZnUtE). In L. sativa, citrate and oxaloacetate concentrations and phosphoenolpyruvate carboxylase and citrate synthase activities increased, while fumarase and malate dehydrogenase activities declined. In B. oleracea no significant response was found in concentrations of carboxylate metabolism or enzyme activity except for a decrease in fumarase activity. These results suggest that a possible factor that induces the tricarboxylic acid cycle could be the low ZnUtE rather than the low Zn concentration under Zn‐deficiency conditions. In L. sativa citrate, oxaloacetate, phosphoenolpyruvate carboxylase, and citrate synthase may play a key role to face Zn deficiency, while in B. oleracea the higher ZnUtE cannot be explained in terms of a rise in OAs synthesis.     

Differential Responses of Conventional and Bt-Transgenic Cotton to Potassium Deficiency

Bacillus thuringensis (Bt) transgenic (insect-resistant) cotton cultivars senesce prematurely under potassium (K⁺) deficiency, more often than conventional cultivars, in the North China Plain. To verify if Bt-transgenic cotton was more susceptible to K⁺ deficit, two transgenic cultivars, ‘CCRI 41’ and ‘DP 99B’, and two conventional cultivars, ‘CCRI 35’ and ‘CCRI 36’, selected from widely used cultivars in China, were used in a seedling hydroponic study. The culture solution K⁺ concentration was 0.5 mM for high K⁺ and 0.02 mM for low K⁺ conditions. Seedlings of all four cultivars accumulated more dry matter and K⁺ when grown at high K⁺ than low K⁺ conditions. However, under low K⁺ condition, the dry weight and K⁺ content of Bt-transgenic cultivars CCRI 41 and DP 99B were lower than those of the conventional cultivars CCRI 36 and CCRI 35. The results indicated that Bt-transgenic cultivars CCRI 41 and DP 99B were more sensitive to K⁺ deficiency than conventional cultivars CCRI 36 and CCRI 35, which could be the reason for premature senescence symptoms observed from fields of Bt-transgenic cotton under K⁺ deficiency. Seedlings of all four cultivars had a higher K⁺ use efficiency (KUE) under low K⁺ than high K⁺ conditions, but the KUE did not account for the differential responses between Bt-transgenic and conventional cultivars at the low K⁺ concentration. The K⁺ depletion results did not reveal the mechanism for the above differential responses in V_max and K_m of the seedlings either. Further experiments with more cultivars are needed to clarify the differential mechanisms in these genotypes.     

Yield and Yield Components and Phosphorus Use Efficiency of Lowland Rice Genotypes

Phosphorus deficiency is main constraints for lowland rice production in various rice producing regions of the world. A greenhouse experiment was conducted using lowland (Inceptisol) soil with the objective to determine response of seven lowland rice (Oryza sativa L.) genotypes to phosphorus fertilization and to evaluate their phosphorus (P) use efficiency. Phosphorus treatments included control (0 mg P kg^?1) and 200 mg P kg^?1 of soil. Plant height and shoot dry weight were significantly (P < 0.001) influenced by P treatments. Phosphorus X genotypes interaction was significant for shoot dry weight, indicating different response of genotypes under two P levels. At low P level, none of the genotypes produced grain yield, indicating original P level in the soil was too low for lowland rice yield. However, genotypes differed significantly in grain yield at high P level. Panicle number, panicle length, and thousand grains weight had a significant quadratic association with grain yield. However, spikelet sterility had a significant linear negative association with grain yield. The P use efficiency expressed as agronomic efficiency (AE), physiological efficiency (PE), agro-physiological efficiency (AP), apparent recovery efficiency (ARE), and utilization (UE) were significantly different among genotypes. These efficiencies were having significantly positive association with grain yield, with exception to ARE, indicating improving grain yield with improved P use efficiencies in rice.     

LOWLAND RICE GENOTYPES EVALUATION FOR PHOSPHORUS USE EFFICIENCY

ABSTRACT

Phosphorus (P) deficiency is the most yield-limiting factor in lowland rice production in Inceptisols of Brazil. A greenhouse experiment was conducted to evaluate 12 genotypes of lowland rice (Oryza sativa L.) using an Inceptisol (Typic Haplaquepts). The P treatments were: low (0?mg?P?kg^?1), medium (100?mg?P?kg^?1), and high (400?mg?P?kg^?1). Significant (P<0.01) genotypes differences in P-use efficiency were found. On the basis of P-use efficiency, genotypes were classified as efficient and responsive, efficient and non-responsive, non-efficient and responsive, and non-efficient and non-responsive. From a practical point of view, efficient and responsive and efficient and non-responsive genotypes are the most desirable ones. Among the 12 genotypes tested, none were found to be efficient and responsive and genotypes CNA7553, CNA7591, CNA7601, and Aliança were found to be efficient and non-responsive. Among the yield components, panicle length and harvest index were significantly affected by P levels and genotypes and P and genotypes interactions were significant for these two parameters. However, panicle number was significantly influenced only by P treatment. Among the yield components, panicle number, harvest index, and panicle length were significantly (P<0.01) related to grain yield.     

Boron nutrition and mobility,and its relation to the elemental composition of greenhouse grown root crops I. Rutabaga

Abstract

The nutrition and mobility of B, and its relation to the elemental composition of two cultivars of rutabaga (Brassica napus ssp. rapifera cv. Laurentian and Wilhelmsberger) plants were investigated in greenhouse experiments. Laurentian exhibited a greater response than Wilhelmsberger to continuing B deficiency as indicated by the severity in the roots of brown heart, of external roughness and elongation and of the decrease in B concentration. Signs of B deficiency were not found when the B contents of the root and young leaves were 27 and 56 ug g‐1 DM respectively. Root B levels of 14 and 17–20 μg g^‐1 gave moderate and slight internal signs of brown discoloration. Foliar applications of B partially restored the B concentrations of the roots; however, the mechanism of movement was unclear. The Mg, Mn and Zn contents of roots were the only elements that consistently increased and accumulated under B deficiency. The relative element composition of the root compared to the mature leaves is consistent with the root being supplied predominantly with nutrients by the phloem. Nutrient retranslocation was assessed from the ratio of element concentration in the roots or young leaves to that in the mature leaves. Although Mg, Mn and B exhibited limited mobility under adequate B nutrition they were translocated from mature leaves to younger tissues under B starvation. It is concluded that Wilheimsberger is by virtue of its greater capacity for the retranslocation of B to roots, less sensitive to B deficiency and the brown heart disorder.     

PHENOLOGY AND SEED QUALITY RESPONSE OF RAPE (B. NAPUS) VERSUS MUSTARD (B. JUNCEA) TO SULFUR AND POTASSIUM FERTILIZATION IN NORTHWEST PAKISTAN

Inappropriate sulfur and potassium fertilization, particularly with continued soil nutrient mining and yearly fluctuations in rainfall, are major factors contributing to slow growth and low seed quality of canola in northwestern Pakistan. A field experiment was conducted in 2007–2008 on a sulfur (S) and potassium (K) deficient clay loam soil under irrigation at the research farm of NWFP (Northwest Frontier Province) Agricultural University, Peshawar, Pakistan, with an objective to determine response of phenology and seed quality of Brassica oilseed rape versus mustard to S and K fertilizer application. Twenty treatments in a randomized complete block design were consisted of two oilseed genotypes [rape (B. napus canola) and mustard (B. juncea canola)], at three rates each of S (15, 30, and 45 kg S ha^?1) and K (30, 60, and 90 kg K ha^?1), plus control (no K and S applied). Days to flowering, pod formation, seed filling duration and maturity were enhanced with K and S fertilization compared to control plots. The species B. napus took more time to flowering, pod formation, seed filling duration and maturity compared to B. juncea. Both genotypes responded positively for seed quality (oil and protein content) to K and S fertilization, but the magnitude of response varied with level and combination of K and S fertilization. Delay in the phenological stages showed negative relationship with oil and protein content in seed of both genotypes. It is concluded that a combination of 60 kg K ha^?1 + 30 kg S ha^?1 would accelerate phenological development and improve seed quality of rape and mustard in the study area.