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1.
A rhizobox experiment was conducted to compare the differences of soil potassium (K) distribution and absorption between two cotton (Gossypium hirsutum L.) genotypes under drought and K‐deficit conditions. Treatments included two levels of water (drought and optimum soil moisture: 25% and 35% volumetric water content) and K fertilizer rates (0 and 0.48 g potash kg?1 soil) applied to two cotton genotypes (namely HEG and LEG). Both the genotypes showed significant differences in total K accumulation without exogenous K addition. After absorption, soil content of the readily available potassium (RAK) decreased rapidly. This promoted the conversion of the mineral K into slowly available potassium (SAK). Drought significantly decreased the cotton growth and K use efficiency, and thereby reduced the effect of K fertilizer. Consequantly, the contents of RAK and SAK were greatly increased. However, K bioavailability was decreased under water stress conditions. Differences in root parameters and soil microorganisms between two cotton genotypes were significantly increased and had marked relations with available soil K contents. This study provides important information for understanding the mechanism of K use efficiency, especially under water and K stress.  相似文献   

2.
Nitrogen fixation in faba bean (Vicia faba cv. Mesay) as affected by sulfur (S) fertilization (30 kg S ha–1) and inoculation under the semi‐arid conditions of Ethiopia was studied using the 15N‐isotope dilution method. The effect of faba bean–fixed nitrogen (N) on yield of the subsequent wheat crop (Triticum aestivum L.) was also assessed. Sulfur fertilization and inoculation significantly (p < 0.05) affected nodulation at late flowering stage for both 2004 and 2005 cropping seasons. The nodule number and nodule fresh weighs were increased by 53% and 95%, relative to the control. Similarly, both treatments (S fertilization and inoculants) significantly improved biomass and grain yield of faba bean on average by 2.2 and 1.2 Mg ha–1. This corresponds to 37% and 50% increases, respectively, relative to the control. Total N and S uptake of grains was significantly higher by 59.6 and 3.3 kg ha–1, which are 76% and 66% increases, respectively. Sulfur and inoculation enhanced the percentage of N derived from the atmosphere in the whole plant of faba bean from 51% to 73%. This corresponds to N2 fixation varying from 49 to 147 kg N ha–1. The percentage of N derived from fertilizer (%Ndff) and soil (%Ndfs) of faba bean varied from 4.3% to 2.8 %, and from 45.1% to 24.0%, corresponding to the average values of 5.1 and 47.9 kg N ha–1. Similarly, the %Ndff and %Ndfs of the reference crop, barley, varied from 8.5 % to 10.8% and from 91.5% to 89.2%, with average N yields of 9.2 and 84.3 kg N ha–1. Soil N balance after faba bean ranged from 13 to 52 kg N ha–1. Beneficial effects of faba bean on yield of a wheat crop grown after faba bean were highly significant, increasing the average grain and N yields of this crop by 1.11 Mg ha–1 and 30 kg ha–1, relative to the yield of wheat grown after the reference crop, barley. Thus, it can be concluded that faba bean can be grown as an alternative crop to fallow, benefiting farmers economically and increasing the soil fertility.  相似文献   

3.
Thirteen inbred and hybrid pumpkin (Cucurbita moschata Poir.) genotypes, differing on the basis of harvest maturity, were evaluated for NO3‐uptake from solution, dry matter production, and distribution of absorbed N in plant parts, over the 8‐day time‐course corresponding to the period of the vine initiation stage. The pattern of NO3‐ removal from solution was linear in the early genotypes and curvilinear in late genotypes. Genotypic differences in NO3 ‐ absorption were found in early genotypes but not in late ones. In early genotypes, NO3 ‐ uptake from solution was greater in the Fl hybrid than in the parents, but no apparent relationship was found between parents and Fl progeny in their ability to absorb NO3 ‐ from solution. Genotypic differences in dry weight and total N accumulation in roots, stems, and leaves were larger in early genotypes than in late genotypes. Differences in total N concentrations in plant parts among early and late genotypes were small, and occurred only in leaves. As a group, late genotypes removed more NO3 ‐ from solution, produced more dry matter, and accumulated more total N than early genotypes, but differences between individual early and late hybrids were small. The results indicated a positive relationship between NO3 ‐ removed from solution and vegetative growth, suggesting that NO3 ‐ uptake may be a demand driven process.  相似文献   

4.
Abstract

Efficient nutrient and water use are two important considerations to obtain good harvests of wheat. This necessitates the development of an effective nutrient management technique that not only increases yield, but simultaneously can save nutrient and water use. In this context, a field experiment was conducted at Indian Agricultural Research Institute, New Delhi, India to evaluate the residual effect of sesbania and rice bean (in-situ), subabul (ex-situ) green manuring and Zinc (Zn) fertilization, using chelated Zn-ethylenediaminetetraacetic acid (Zn-EDTA) on nutrient use, yields and water productivity of wheat under rice–wheat cropping system. Among residual effects of green manure crops and Zn fertilization, sesbania and foliar spray of 0.5% chelated Zn-EDTA at 20, 40, 60 and 80 days after sowing (DAS) recorded significantly higher nutrient content and uptake and yields than other green manure crops and Zn treatments. Residual effect of sesbania saved about 46.5?×?103 and 30.5?×?103 L irrigation water per tonne of wheat over subabul and rice bean, respectively. Foliar spray of 0.5% chelated Zn-EDTA at 20, 40, 60 and 80 DAS saved about 55.5?×?103, 47?×?103 and 13?×?103 L irrigation water per tonne wheat over residual effect of 5?kg Zn ha?1 through chelated Zn-EDTA as soil application, 2.5?kg Zn ha?1 through chelated Zn-EDTA as soil application + 1 foliar spray of 0.5% chelated Zn-EDTA at flowering and foliar spray of 0.5% chelated Zn-EDTA at active tillering?+?flowering?+?grain filling, respectively. Correlation analysis showed positive correlation between Zn uptake and grain yield.  相似文献   

5.
The recent drought in South Africa has reduced the production of both dryland and irrigated wheat. This study evaluated physiological traits of irrigated wheat genotypes in response to water stress (WS) imposed at different growth stages. A 8?×?2?×?3 [(genotypes)?×?(water treatmets; stresses and non-stressed)?×?(growth stages; tillering, flowering and grain filling)] factorial experiment based on a randomised complete block design with three replicates was conducetd. In general, the rate of photosynthesis was unaffected by WS except for genotypes LM43 at tillering and LM98 at grain filling. Stomatal conductance (SC) and transpiration rate (Tr) followed the same treand except for genotype LM35 which reduced its SC and Tr significantly at grain filling. Instantaneous waster use efficiency (IWUE) of genotype LM35 and LM57 was unaffected (p?>?0.05) by WS at tillering but at flowering stage it was affected. However, at grain filling IWUE was affected (p?<?0.05) in genotypes LM35, ML57, LM79 and LM 98. The relative water content was unaffected at tillering except for LM35 and LM47 genotypes whereas at flowering LM57, ML79, LM83 and LM98 were affected. These results indicate some degree of drought tolerance of these genotypes at different growth stages.  相似文献   

6.
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   

7.
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8.
To investigate the seed protein and major mineral nutrient (Fe, Zn, P, and N) contents and their accumulation procedure in the seeds of common bean (Phaseolus vulgaris L.), a biennial experiment was conducted under two contrasting moisture regimes (normal irrigation and water deficit). Seed reserves of eight genotypes (WA4502-1, WA4531-17, Akhtar, D81083, AND1007, KS21486, MCD4011, and COS16) were investigated at four stages of seed filling period (SFP). Split-plot experiments were performed as randomized complete block design with four replications. The results showed significant differences in the evaluated characteristics in both factors, the genotypes and the moisture regimes. Fe content of the seeds was affected the most by drought stress and reduced in all stages, while seed nitrogen and protein contents were affected the least under stress condition. The percentages of reductions due to water deficit were higher in stage 1 for Fe, stage 2 for Zn, and stage 4 for P and N. In the stage 3, minerals had the least changes. Nitrogen content of the seeds at mid-stages of SFP increased slightly under drought stress. Drought stress also caused 39–69% reductions in the grain yield of the genotypes. Under drought stress condition, the concentrations of Fe and N in the white bean seeds were less than that of the red and the Chitti genotypes. However, the seed P contents of the white bean seeds were higher than that of the other genotypes.  相似文献   

9.
The effects of phosphorus supply (0, 30, and 90 mg P kg‐1) on growth, N2 fixation, and soil N uptake by soybean (Glycine max (L.) Merr.) were studied in a pot experiment using the 15N isotope technique. Phosphorus supply increased the top dry matter production at flowering and the dry matter production of seeds, straw, pod shells, and roots at late pod filling of inoculated soybeans. Phosphorus supply reduced the N concentration of plant tops at flowering, but increased the amount of N accumulated at both flowering and late pod filling. In inoculated soybeans total N accumulation paralleled the dry matter production. The P concentration in above‐ground plant parts of nodulated soybeans was not affected by P application. At flowering only 18 to 34% of total N was derived from N2 fixation, whereas as much as 74% was derived from N2 fixation at late pod filling. Only the addition of 90 mg P kg‐1 soil significantly increased the amount of N2 fixed at the late pod filling stage. Phosphorus supply did not influence the uptake of fertilizer or soil N in soybeans, even if the root mass was increased up to 60% by the P supply.  相似文献   

10.
Three-week-old nodulated faba bean plants were subjected to different levels of drought stress (onehalf, one-quarter, or one-eighth field capacity) for 5 weeks. Half the stressed plants were treated with KCl at 10 mg kg-1 soil or 150 mg kg-1 soil at the beginning of the drought stress. Nodulation and nitrogenase activity were significantly decreased by increasing drought stress. Leghaemoglobin and protein contents of nodule cytosol were also severely inhibited by drought sttess. This decline was attributed to the induction of protease activity. However, carbohydrate contents of the nodule cytosol increased significantly. This accumulation was attributed to a sharp decline in invertase activity and low use of sugar by the bacteroids We conclude that harmful effects of water deficits can be alleviated by increasing K+ supplementation.  相似文献   

11.
Wheat (Tritcum aestivum L.) genotypes were screened and characterized for performance under salt stress and/or water‐logging. In a solution‐culture study, ten wheat genotypes were tested under control, 200 mM–NaCl salt stress and 4‐week water‐logging (nonaerated solution stagnated with 0.1% agar), alone or in combination. Shoot and root growth of the wheat genotypes was reduced by salinity and salinity × water‐logging, which was associated with increased leaf Na+ and Cl– concentrations as well as decreased leaf K+ concentration and K+ : Na+ ratio. The genotypes differed significantly for their growth and leaf ionic composition. The genotypes Aqaab and MH‐97 were selected as salinity×water‐logging‐resistant and sensitive wheat genotypes, respectively, on the basis of their shoot fresh weights in the salinity × water‐logging treatment relative to control. In a soil experiment, the effect of water‐logging was tested for these two genotypes under nonsaline (EC = 2.6 dS m–1) and saline (EC = 15 dS m–1) soil conditions. The water‐logging was imposed for a period of 21 d at various growth stages, i.e., tillering, stem elongation, booting, and grain filling alone or in combinations. The maximum reduction in grain yield was observed after water‐logging at stem‐elongation + grain‐filling stages followed by water‐logging at grain‐filling stage, booting stage, and stem‐elongation stage, respectively. Salinity intensified the effect of water‐logging at all the growth stages. It is concluded that the existing genetic variation in wheat for salinity × water‐logging resistance can be successfully explored using relative shoot fresh weight as a selection criterion in nonaerated 0.1% agar–containing nutrient solution and that irrigation in the field should be scheduled to avoid temporary water‐logging at the sensitive stages of wheat growth.  相似文献   

12.
Drought is a major factor limiting crop production worldwide. Barley is a well‐adapted cereal that is largely grown on dry marginal land where water and salinity are the most prevalent environmental stresses. This study was carried out to investigate the effects of drought stress and subsequent recovery on growth, photosynthetic activity, water relations, osmotic adjustment (OA), and solute accumulation of wild (Hordeum maritimum) and cultivated barley (H. vulgare L.). In a pot experiment, 60 d old seedlings were subjected to drought stress for 0, 7, 14, 21, or 28 d, and then re‐watered to recover for up to 21 d. Plants were harvested at the end of each of these drought/recovery treatments. Drought significantly reduced fresh and dry weights at the whole‐plant level, photosynthetic activities, and solute and water potentials, while increasing leaf Na+ and K+ concentrations. The adverse effects of drought on growth were more marked in cultivated barley than in wild barley and the reverse was true for photosynthetic activities. During recovery, all wild barley seedlings completely recovered. For cultivated barley seedlings, rehydration had a beneficial effect on growth and photosynthesis, independent of treatment duration, but complete recovery did not occur. The reduction in leaf solute potential at full turgor in drought‐stressed barley, relative to the control, suggests active OA which was more significant in wild barley than in cultivated barley. OA was mainly due to the accumulation of inorganic (K+ in cultivated barley and Na+ in wild barley) and organic (soluble sugars and proline) solutes. The results suggest that OA is an important component of the drought‐stress adaptation mechanism in wild barley, but is not sufficient to contribute to drought tolerance in cultivated barley. In the latter species, the results show that even short periods (as little as 7 d) of water deficit stress had considerable long‐term effects on plant growth.  相似文献   

13.
Common bean (Phaseolus vulgaris L.) proved to be very sensitive of low pH (4.3), with large genotypic differences in proton sensitivity. Therefore, proton toxicity did not allow the screening of common bean genotypes for aluminium (Al) resistance using the established protocol for maize (0.5 mM CaCl2, 8 μM H3BO3, pH 4.3). Increasing the pH to 4.5, the Ca2+ concentration to 5 mM, and addition of 0.5 mM KCl fully prevented proton toxicity in 28 tested genotypes and allowed to identify differences in Al resistance using the inhibition of root elongation by 20 μM Al supply for 36 h as parameter of Al injury. As in maize, Al treatment induced callose formation in root apices of common bean. Aluminium‐induced callose formation well reflected the effect of Ca supply on Al sensitivity as revealed by root‐growth inhibition. Aluminum‐induced callose formation in root apices of 28 bean genotypes differing in Al resistance after 36 h Al treatment was positively correlated to Al‐induced inhibition of root elongation and Al contents in the root apices. However, the relationship was less close than previously reported for maize. Also, after 12 h Al treatment, callose formation and Al contents in root apices did not reflect differences in Al resistance between two contrasting genotypes, indicating a different mode of the expression of Al toxicity and regulation of Al resistance in common bean than in maize.  相似文献   

14.
A pot experiment was conducted to study the response of nodulated bean (Phaseolus vulgaris L.), vars. Ceca and Montalbán, to inoculation with the arbuscular‐mycorrhizae (AM) Glomus spurcum strain IES‐3 and G. mosseae strain IES‐8 in two non‐sterilized non‐amended soil substrates (S‐l and S‐2) of contrasting fertility. S‐l was an acid soil (pH 5.0) with 77% exchangeable aluminum (Al), low available phosphorus (P) (3.5 ug g‐1 dry soil) and 1.8% organic matter. S‐2 was a soil with pH 7.0, 7.9 μg P g‐1 dry soil, 9.6% organic matter and no exchangeable Al. Plants growing in S‐1 (S‐1 plants) and S‐2 (S‐2 plants) soils were sampled at the beginning of the flowering stage. S‐1 and S‐2 plants were nodulated by the rhizobial populations native of each soil. S‐1 plants of both varieties did not respond to AM inoculation in term of shoot and root mass, P content, relative abundance of ureides (RAU) and seed yields. Only the total chlorophyll, chlorophyll‐a, chlrophyll‐a/b ratio and nodule mass were significantly enhanced in AM‐inoculated plants. Increased total reducing sugars concentration was detected in roots of S‐1 plants inoculated with G. mosseae. S‐2 plants displayed significantly higher shoot and nodule mass as well as increased total chlorophyll, chlorophyll‐a, chlorophyll‐a/b ratio and P content than S‐1 plants, regardless of the variety and AM inoculation. S‐2 plants of the var Ceca showed a two fold increase in seed yields but similar RAU values (>60%) when compared to S‐1 plants of the same variety. In contrast, the significant increase in RAU detected in S‐2 plants of the var Montalban was not translated into higher seed yields. In S‐2, the productivity of plants of the var Ceca doubled that of the var Montalban. For both bean varieties the highest significant P content and seed yield were observed exclusively in S‐2 plants inoculated with G. mosseae. This Glomelean strain enhanced the sink‐source ratio of the S‐2 plants as evidenced by the higher total reducing sugar concentration in the root mass. Arbuscular‐mycorrhizae inoculation significantly decreased the acid phosphatase activity in the rhizosphere of S‐1 and S‐2 plants, respectively, pointing toward a negative effect of foreign AM on the native microbial biomass. The effectiveness of the rhizobial populations native of each soil type and the weak response elicited by G. mosseae in S‐2 plants do not justify, at present, the inclusion of foreign inocula in the bean crops carried out at S‐1 and S‐2 soils of the Sucre State of Venezuela. Results also indicated the higher adaptability of var Ceca to conditions prevailing in S‐1 and S‐2.  相似文献   

15.
ABSTRACT

Soil fertility and water use are two important aspects that influence rice productivity. This study was conducted to evaluate the performance of in-situ (sesbania and rice bean) and ex-situ (subabul) green manuring along with zinc fertilization on water productivity and soil fertility in rice under rice–wheat cropping system at Indian Agricultural Research Institute, New Delhi, India. Sesbania incorporation recorded higher total water productivity (2.20 and 3.24 kg ha?1 mm?1), available soil nutrients, organic carbon, alkaline phosphatase activity, microbial biomass carbon and increased soil dehydrogenase activity by 39.6 and 26.8% over subabul and rice bean respectively. Among interaction of green manures and zinc fertilization, subabul × foliar application of chelated zinc-ethylenediaminetetraacetic acid at 20, 40, 60 and 80 days after transplanting recorded highest total water productivity (2.56 and 3.79 kg ha?1 mm?1). Foliar application of chelated Zn-EDTA at 20, 40, 60 and 80 days after transplanting recorded significantly higher water productivity than other Zn treatments, however it was statistically similar with foliar application of zinc at active tillering + flowering + grain filling. Sesbania × 5 kg Zn ha?1 through chelated Zn-EDTA, recorded highest available nitrogen, phosphorus, potassium, zinc, manganese, copper and iron than other green manure and Zn fertilization interactions, although it was statistically similar with rice bean × 5 kg Zn ha?1 through chelated Zn-EDTA as soil application. Sesbania × foliar application of 5 kg Zn ha?1 through chelated Zn-EDTA as soil application recorded highest soil enzymatic activities and microbial biomass carbon.  相似文献   

16.
It is surmised that domestication has reduced geneticvariability in the common bean (Phaseolusvulgaris L.). However, little is known about leaf anatomy responses to water stress in wild or domesticated forms ofP. vulgaris. In this study,anatomical variation was evaluated in watered and water stressed plants of wild and domesticated genotypes of P.vulgaris from Mexico, growing under greenhouse conditions. Five terminal leaflets of completely expanded leaves wereused to evaluate leaf area (LA) and theirmiddle-regions to evaluate leaf thickness (LT), and various anatomical features. Domesticated genotypes showed bigger LAthan that of the wild ones; there was an effect due to the origin of materials, LA being bigger in genotypes from warm and humid lands that those from dry and temperate ones. No differences were detected in LT among materials; however, in domesticated plants the palisadeparenchyma predominated over the spongy one, contrasting with thewild genotypes. Under drought conditions, stomatal abortion was observed in wild and domesticated genotypes, especially on theabaxial surface. We conclude that, in fact, there are contrasting differences in leaf anatomy among wild and domesticated forms of Mexican Phaseolus vulgaris. Results suggest that domestication not only favours the enlargement of the LA, but also an increase in palisade parenchyma, suggesting a divergence toward assimilation in domesticated forms, in contrast with a better internal gas diffusion in wild forms. Domestication seems to have accentuated stomatal abortion as means of a transpirational control mechanism to counteract the effects of drought.  相似文献   

17.
Depletion of soil nutrients due to continuous cultivation without adequate external fertilization is one of the challenges facing many smallholder farmers in western Kenya. This study was conducted to assess the effects of organic (water hyacinth compost), inorganic (urea) nitrogen (N) sources, and commercial Rhizobia inoculant on the yield of common bean (Phaseolus vulgaris) for two consecutive seasons in the short rains (2013) and long rains (2014). The experiments were laid out in a randomized complete block design and replicated four times. Triple superphosphate was applied to all treatments except those with compost to ensure that the soil had adequate phosphorus (P). Yellow and Rose coco bean varieties grown with urea and inoculated with commercial Rhizobia inoculant gave significantly higher yield of 382 kg ha?1 and 341 kg ha?1, respectively in the short rains (SR) season. In the long rains (LR) season bean yield was high in water hyacinth compost (1526 kg ha?1) and control with non-limiting P (1300 kg ha?1) treatments. Commercial Rhizobia inoculant did not significantly increase in yield in the SR and LR seasons. There was no significant influence on soil properties after two seasons of continuous cultivation of common bean and application of organic and inorganic fertilizers. These results demonstrate that water hyacinth compost improved bean yield in the LR season. However, longer field testing and economic analysis are required for it to be recommended as a substitute for inorganic N source among smallholder farmers.  相似文献   

18.
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.  相似文献   

19.
Terminal drought stress (drought at reproductive growth stage) has been considered a severe environmental threat under changing climatic scenarios and undoubtedly inhibits sunflower production. A field study was conducted to explore the potential role of foliar applied boron (B) (0, 15, 30, 45 mg L?1) at late growth periods of sunflower in alleviating the adversities of terminal drought stress (75, 64, 53 mm DI) grown from inflorescence emergence to maturity stages. The plant water relations such as leaf relative water content (RWC), water potential (Ψw), osmotic potential (Ψs), and turgor pressure (Ψp) were increased significantly with B foliar sprays while exposed to terminal drought stress. Foliar B application considerably improved the nitrogen and B concentrations in leaf and seed tissues, and also chlorophyll a and b pigments under terminal drought stress conditions. Drought-induced proline accumulation prevented the damages caused by drought stress, nevertheless, B foliar spray increased its contents. Compared to well-watered conditions, terminal drought stress substantially declined the growth performance in terms of reduced leaf area index (LAI), crop growth rate (CGR), net assimilation rate (NAR), and total dry matter (TDM) production; however, foliar B supply (30 mg L?1) might be helpful for improving drought tolerance in sunflower with reduced growth losses.  相似文献   

20.
Dry bean (Phaseolus vulgaris L.) generally responds to nitrogen (N) fertilizer with increased yields, but N can delay maturity and cause yield and quality losses from early fall frost. Maintaining adequate zinc (Zn) nutrition in bean promotes earlier maturity. This study was conducted to determine if Zn application can overcome maturity delays possible with the N recommended for high bean yields. Three zinc sulfate (ZnSO4) treatments (0 Zn, 5.6 kg Zn/ha banded adjacent to the row, and 11.2 kg Zn/ha broadcast and incorporated) were applied in combination with five N rates (0, 45, 90, 134, and 179 kg/ha). Whole plants were sampled at the R1 growth stage (onset of flowering) and analyzed for N and Zn content. Maturity was estimated by determining the percentage of mature pods at the R8‐R9 growth stage. Yields were estimated by harvesting 12.2 m of row at maturity. Zinc fertilization generally increased mature‐pod percentages with banded Zn producing the most consistent response. Zinc did not consistently affect bean yield. Yield and mature‐pod percentage generally increased and decreased, respectively, with increasing N rate. Whole‐plant N concentrations increased linearly with increasing N rate but did not differ among Zn treatments. Mean plant Zn concentrations were increased by Zn fertilizer and related well with mature‐pod percentage means. In situations of high available N, short growing seasons, or with late planting, Zn applications can reduce the risk of crop losses from early fall frost.  相似文献   

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