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1.
Heliyon ; 9(3): e14139, 2023 Mar.
Article in English | MEDLINE | ID: mdl-36923888

ABSTRACT

Women-headed households (WHHs) have limited access to agricultural inputs and extension services relative to male-headed households (MHHs) which may lead to yield gaps, poorer livelihoods and greater food insecurity. Since lower fertilizer use by WHHs will restrict crop yield, we examined how limited access to fertilizer inputs and extension services was reflected in nutrient use gaps relative to Government recommendations. A total of 80 WHHs were randomly selected for interview from four Agro-ecological Zones (AEZs) covering five representative districts of Bangladesh to assess, for the first time, nutrient use gaps of WHHs under five rice-based cropping patterns. Data collected from 576 MHHs (reported elsewhere) was also utilized to examine nutrient use gaps, crop yields and farm income between MHHs and WHHs. The nutrient use rates were compared with the government Fertilizer Recommendation Guides (FRG): FRG-2012 and FRG-2018. The WHHs underuse N, P, K, S and Zn under fully rice-based cropping patterns, while MHHs overuse those nutrients, but WHH tend to overuse N, P, and K for patterns with potato and watermelon crops. WHHs seem to prioritize high-value crops for fertilizer use, but even yield was 14%, 11%, 17% and 15% lower for irrigated rice, maize, potato and watermelon, respectively compared to smallholder MHHs under diverse rice-based cropping patterns. Overall, WHHs had 10% and 14% lower farm incomes than MHHs under fully rice-based and high-value cropping patterns, respectively. Financial losses for both WHHs and the government due to overuse of NPK on high-value potato crops were estimated at around 63 and 115 USD ha-1, respectively. However, the socio-demographic information suggested that effective extension services targeted to WHH, easing of social restrictions on their mobility, access of WHHs to fertilizers at Govt. fixed price and improved financial capability through better credit access could bring WHHs towards balanced fertilizer use practices in the EGP.

2.
PLoS One ; 17(7): e0272146, 2022.
Article in English | MEDLINE | ID: mdl-35901052

ABSTRACT

Intensive cropping systems with diverse cropping patterns present a challenge for nutrient management on smallholder farms. Government-endorsed recommendations for crop fertilizer use are designed to assist farmers achieve profitable and balanced nutrient inputs, but it is unclear how closely farmers follow these recommendations. We identified farmers' current nutrient use gaps (overuse or underuse) relative to the Government-endorsed recommended nutrient doses in two cropping patterns in three representative Agro-ecological Zones of Bangladesh. A total of 330 farms were surveyed in 2019 from three farm size categories (referred to as large-, medium and small-scale) and their gaps in nutrient use were assessed relative to Government-endorsed Fertilizer Recommendation Guides (FRG) published in 2012 and in 2018: FRG-2012 and FRG-2018. The large- and medium-scale farms used 11-16%, 80-90% and 21-30%, respectively, over-doses of NPK in the cropping season under fully rice-based cropping pattern relative to FRG-2012 recommendations, while the over-dose levels were much lower for small-scale farms. Small-scale farms used much less than recommended S, Mg, Zn, B and organic manure (OM) rates relative to FRG-2012. The FRG-2018, which increased N and K recommendations but decreased the P recommendation for rice crops relative to FRG-2012, shows that all farms can decrease the dose of P (by 50%) while small-scale farms need to increase the dose of N (7%), K (16%), S (20%) and to apply Zn in the fully rice-based cropping pattern. On the other hand, the farms could greatly reduce NPK (19%, 86% and 44%, respectively) use while increasing S (14%), Mg, Zn, B and OM use relative to FRG-2018 in the pattern with the high-value potato crop. To increase crop profitability, enhance food security and save Government treasury in the Eastern Gangetic Plain enabling approaches are needed to effectively communicate the benefits of balanced nutrient use practices to farmers.


Subject(s)
Fertilizers , Oryza , Agriculture , Crops, Agricultural , Farmers , Farms , Government , Humans , Manure
3.
Agron Sustain Dev ; 42(4): 59, 2022.
Article in English | MEDLINE | ID: mdl-35755936

ABSTRACT

Overuse or underuse of nutrients relative to recommendations is a likely cause of crop yield gaps and an impediment to the achievement of food security. Government-endorsed recommendations are developed to deliver the best evidence-based advice on balanced fertilizer; however, deviations of farmers' nutrient use from the recommendations are rarely examined. This study chose the salt-affected coastal zone of the Ganges Delta, where low crop productivity and cropping intensity by smallholders limit their income, to determine current nutrient use gaps for the first time of three cropping patterns in two representative districts of Bangladesh. A total of 246 farms were surveyed from three farm sizes. Farmers' nutrient use gaps were compared with Fertilizer Recommendation Guides published in 2012 (FRG-2012) and 2018 (FRG-2018). Relative to FRG-2012 recommendations, farmers used 12%, 70%, and 11% overdoses of N, P, and K, respectively, under two fully rice-based cropping patterns, but the level of overdoses increased with farm size. Rates of K (14%), S (28%), and Zn use were below the FRG-2012 recommendations, especially for the smallest category of farms. However, the FRG-2018, increased recommended N (5%), K (62%), S (12%), and Zn rates but reduced P (25%) rates for fully rice-based cropping patterns. In contrast with rice, regardless of farm size, farmers applied overdose nutrients to watermelon but compensated with underdoses in the subsequent monsoon rice implying that farmers prioritized fertilizer expenditure on the most profitable crop. For the cropping pattern with watermelon, farmers could reduce the use of N (69%) and P (46%) and increase the use of K (48%), S (5%), and B. Reducing NPK use gaps can save treasury for both the farmers and the governments by 39.1 and 73.8 USD ha-1, respectively, under fully rice-based cropping patterns. Finally, our findings suggest there is scope to promote crop yields and sustainable intensification through balanced fertilizer use in a vulnerable saline region. Supplementary Information: The online version contains supplementary material available at 10.1007/s13593-022-00797-1.

4.
Waste Manag Res ; 40(8): 1277-1284, 2022 Aug.
Article in English | MEDLINE | ID: mdl-34894886

ABSTRACT

The use of organic fertilisers and soil amendments are almost universally recommended for improving the organic matter levels and maintaining soil health, but few studies documenting the actual availability and quality of such materials on smallholder farms are available. We selected a case study of 300 households from northern and southern Bangladesh to assess the types of waste materials available for recycling and their usage patterns at household level and we applied a novel approach to empirically identify household waste as input inefficiency in a production context. Northern districts have highly intensive farming systems whereas southern districts have low intensity farming. The total amount of agricultural waste produced at household level was estimated at 822 kg per month. Cow dung contributed about 65% of the total waste followed by animal feed refusal waste (11%), garbage (7%) and kitchen waste (6%). Most of the farmers utilised cow dung and wastes as organic fertiliser and lesser amounts as cooking fuel. Econometric analysis shows that the number of cattle and small ruminant per holding, total area of cultivated land and family size were significant factors that influence the amount of waste production at household level. Each household can reduce the chemical fertiliser cost by Tk. 1463 (US$ 17.84) per month by using compost prepared from household waste. There were ample opportunities for compost/vermicomposting and potential markets. The Department of Agricultural Extension from the public sector and private sector agents might motivate farmers to harvest the potential benefits of agricultural waste through effective management and utilisation.


Subject(s)
Agriculture , Fertilizers , Animals , Bangladesh , Cattle , Female , Recycling , Soil
5.
Plants (Basel) ; 10(8)2021 Aug 11.
Article in English | MEDLINE | ID: mdl-34451695

ABSTRACT

Very little is known about the changes that occur in soil organic carbon (SOC) and total nitrogen (TN) under an intensive rice-based cropping system following the change to minimal tillage and increased crop residue retention in the Gangetic Plains of South Asia. The field experiment was conducted for 3 years at Rajbari, Bangladesh to examine the impact of tillage practices and crop residue retention on carbon (C) and nitrogen (N) cycling. The experiment comprised four tillage practices-conventional tillage (CT), zero tillage (ZT), strip-tillage (ST), and bed planting (BP) in combination with two residue retention levels-increased residue (R50%) and low residue (R20%-the current practice). The TN, SOC, and mineral N (NH4+-N and NO3--N) were measured in the soil at different crop growth stages. After 3 years, ZT, ST, and BP sequestered 12, 11, and 6% more SOC, and 18, 13, and 10% more TN, respectively than the conventional crop establishment practice at 0-5 cm soil depth. The accumulation of SOC and TN was also higher compared to the initial SOC and TN in soil. Among the tillage practices, the maximum SOC and TN sequestration were recorded with ST and with R50% that might be attributed to reduced mineralization of C and N in soil particularly with increased residue retention, since decay rates of potentially mineralizable C was lower in the ST with both the residue retention practices. Increased residue retention and minimum tillage practices after nine consecutive crops has altered the C and N cycling by slowing the in-season turnover of C and N, reducing the level of nitrate-N available to plants in the growing season and increasing retained soil levels of SOC and TN.

6.
Front Plant Sci ; 12: 678211, 2021.
Article in English | MEDLINE | ID: mdl-34249045

ABSTRACT

In acid soils, the toxic form of aluminium, Al3+, significantly inhibits root growth and elongation, leading to less water and nutrient uptake. Previous research had shown differential Al toxicity tolerance among cultivated Cicer arietinum L. (chickpea); however, the potential for developing tolerant cultivars is limited by the narrow genetic diversity of cultivated chickpeas. Recent collections from Turkey of wild Cicer species, Cicer reticulatum, and Cicer echinospermum, have increased the available gene pool significantly, but there has been no large-scale screening of wild Cicer for acid tolerance or Al3+ toxicity tolerance. This study evaluated 167 wild Cicer and 17 Australian chickpea cultivars in a series of screenings under controlled growth conditions. The pH of 4.2 and Al concentrations of 15 and 60 µM Al were selected for large-scale screening based on dose response experiments in a low ionic strength nutrient solution. The change in root length showed better discrimination between tolerant and sensitive lines when compared with shoot and root dry weights and was used as a selection criterion. In a large-scale screening, 13 wild Cicer reticulatum accessions had a higher root tolerance index (≥50%), and eight had higher relative change in root length (≥40%) compared with PBA Monarch, which showed greater tolerance among the Australian domestic cultivars screened. In general, C. reticulatum species were found to be more tolerant than C. echinospermum, while genetic population groups Ret_5, Ret_6, and Ret_7 from Diyarbakir and Mardin Province were more tolerant than other groups. Among C. echinospermum, Ech_6 from the Siv-Diyar collection site of the Urfa Province showed better tolerance than other groups. In this first detailed screening of aluminium toxicity tolerance in the new wild Cicer collections, we identified accessions that were more tolerant than current domestic cultivars, providing promising germplasm for breeding programs to expand chickpea adaptation to acid soils.

7.
Front Plant Sci ; 11: 588065, 2020.
Article in English | MEDLINE | ID: mdl-33329649

ABSTRACT

After aluminum, manganese toxicity is the most limiting factor for crops grown in acidic soils worldwide. But overall, research on Mn toxicity is still limited. The poor acid tolerance of chickpea may be related to Mn toxicity, but there has been no previous screening of chickpea germplasm (nor in its wild Cicer relatives, Cicer reticulatum and Cicer echinospermum) for tolerance to Mn toxicity. A screening technique was developed for tolerance to Mn toxicity using three released cultivars of chickpea (Cicer arietinum L), Ambar, PBA HatTrick, and PBA Striker; one accession each of C. reticulatum and C. echinospermum; and lupin (Lupinus angustifolius) as a Mn-tolerant check, with eight Mn concentrations of 2, 25, 50, 100, 150, 200, 250, and 500 µM Mn as MnSO4 in a low-ionic-strength nutrient solution. The plants were harvested at 14 and 28 days after Mn treatments. The nutrient uptake in shoots (young, old leaves, and the rest of the shoot) and roots was investigated. The best discrimination between tolerant and intolerant Cicer genotypes based on relative shoot dry weight, root dry weight, total root length, and scoring of toxicity symptoms was achieved at 150 µM Mn after 14 days of growth in Mn solution. Among the chickpea cultivars, the greater relative plant growth (both shoot and root) of Ambar and PBA Striker at 100-200 µM Mn contrasted with that of PBA HatTrick, while the C. echinospermum accession was more tolerant to Mn toxicity than C. reticulatum. Manganese tolerance in both domestic cultivars and wild accessions was associated with internal tolerance to excess Mn following greater uptake of Mn and translocation of Mn from roots to shoots.

8.
Plant Physiol Biochem ; 157: 390-401, 2020 Dec.
Article in English | MEDLINE | ID: mdl-33197728

ABSTRACT

In many acidic soils, high concentrations of toxic Al3+ hamper plant growth by restricting root growth which in turn restricts water and nutrient absorption. Previous research showed variation among chickpea (Cicer arietinum L.) and wild Cicer species in root elongation at 15 µM Al or more, but effects on nutrient absorption have not been examined. The variation in nutrient uptake of two chickpea varieties (PBA HatTrick and PBA Striker) and two wild Cicer species (C. echinospermum (C. echi) and C. reticulatum (C. reti)) was determined in low pH (4.2) nutrient solution with increasing Al concentrations (0, 7.5, 15, 30 µM Al). While C. echi, PBA HatTrick and PBA Striker had thicker roots and more lateral roots compared to C. reti, C. reti had greater aluminium tolerance index (AlTI) at 15 and 30 µM Al. The C. echi had higher uptake of root and shoot Al (7.5, 15 and 30 µM Al), P and S (15 and 30 µM Al) while its uptake was marginally lower for Mg, Ca (all Al treatments) and K (15 and 30 µM Al). By contrast, C. reti contained higher shoot Ca concentration at 15 and 30 µM Al and it had lower root Al uptake. Manganese uptake by C. reti roots and shoots were high enough to induce moderate Mn toxicity at 0 and 7.5 µM Al. Therefore, in response to Al toxicity, C. reti maintained greater AlTI and restricted Al uptake while increasing Ca uptake.


Subject(s)
Aluminum/pharmacology , Cicer , Nutrients/metabolism , Calcium/metabolism , Cicer/genetics , Cicer/metabolism , Genotype , Hydrogen-Ion Concentration , Manganese/metabolism , Plant Roots
10.
BJU Int ; 124(4): 554-566, 2019 Oct.
Article in English | MEDLINE | ID: mdl-30113754

ABSTRACT

INTRODUCTION: Prostatic capsular incision (CapI) is an iatrogenic breach of the prostatic capsule during radical prostatectomy (RP) that can cause positive surgical margins (PSMs) in organ-confined (pT2) prostate cancer, or the retention of benign prostatic tissue. We systematically interrogated the literature in order to clarify the definition of CapI, and the implications of this event for rates of PSM and biochemical recurrence (BCR). METHODS: A literature search was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria using the search terms 'capsular incision' AND 'prostatectomy', and variations of each. In all, 18 studies were eligible for inclusion. RESULTS: A total of 51 057 RP specimens were included. The incidence of CapI ranged from 1.3% to 54.3%. CapI definitions varied and included a breach of the prostatic capsule 'exposing both benign or malignant prostate cancer cells', 'malignant tissue only', or 'benign tissue only'. The incidence of PSMs due to CapI ranged from 2.8% to 71.7%. Our meta-analysis results found that when CapI was defined as 'exposing malignant tissue only in organ-confined prostate cancer' there was an increased risk of BCR compared to patients with pT2 disease and no CapI (relative risk 3.53, 95% confidence interval 2.82-4.41; P < 0.001). CONCLUSIONS: The absolute impact of CapI on oncological outcomes is currently unclear due to inconsistent definitions. However, the data imply an association between CapI and PSMs and BCR. Reporting of possible areas of CapI on the operation note, or marking areas of concern on the specimen, are critical to assist CapI recognition by the pathologist.

11.
Curr Urol Rep ; 18(12): 99, 2017 Nov 07.
Article in English | MEDLINE | ID: mdl-29116405

ABSTRACT

PURPOSE OF REVIEW: Bladder neck preservation (BNP) during radical prostatectomy (RP) has been proposed as a method to improve early recovery of urinary continence after radical prostatectomy. However, there is concern over a possible increase in the risk of positive surgical margins and prostate cancer recurrence rate. A recent systematic review and meta-analysis reported improved early recovery and overall long-term urinary continence without compromising oncologic control. The aim of our study was to perform a critical review of the literature to assess the impact on bladder neck and base margins after bladder neck sparing radical prostatectomy. EVIDENCE ACQUISITION: We carried out a systematic review of the literature using Pubmed, Scopus and Cochrane library databases in May 2017 using medical subject headings and free-text protocol according to PRISMA guidelines. We used the following search terms: bladder neck preservation, prostate cancer, radical prostatectomy and surgical margins. Studies focusing on positive surgical margins (PSM) in bladder neck sparing RP pertinent to the objective of this review were included. EVIDENCE SYNTHESIS: Overall, we found 15 relevant studies reporting overall and site-specific positive surgical margins rate after bladder neck sparing radical prostatectomy. This included two RCTs, seven prospective comparative studies, two retrospective comparative studies and four case series. All studies were published between 1993 and 2015 with sample sizes ranging between 50 and 1067. Surgical approaches included open, laparoscopic and robot-assisted radical prostatectomy. The overall and base-specific PSM rates ranged between 7-36% and 0-16.3%, respectively. Mean base PSM was 4.9% in those patients where bladder neck sparing was performed, but only 1.85% in those without sparing. Bladder neck preservation during radical prostatectomy may increase base-positive margins. Further studies are needed to better investigate the impact of this technique on oncological outcomes. A future paradigm could include modification of intended approach to bladder neck dissection when anterior base lesions are identified on pre-operative MRI.


Subject(s)
Margins of Excision , Prostatectomy , Prostatic Neoplasms/pathology , Prostatic Neoplasms/surgery , Urinary Bladder/surgery , Dissection , Humans , Laparoscopy , Male , Treatment Outcome
12.
Z Naturforsch C J Biosci ; 71(7-8): 273-85, 2016.
Article in English | MEDLINE | ID: mdl-27356235

ABSTRACT

Recent studies indicate an extremely high level of tolerance to boron (B) toxicity in Puccinellia distans (Jacq.) Parl. but the mechanistic basis is not known. Puccinellia distans was exposed to B concentrations of up to 1000 mg B L-1 and root B uptake, growth parameters, B and N contents, H2O2 accumulation and ·OH-scavenging activity were measured. Antioxidant enzyme activities including superoxide dismutase (SOD), ascorbate peroxidase, catalase, peroxidase and glutathione reductase, and lipid peroxidation products were determined. B appears to be actively excluded from roots. Excess B supply caused structural deformations in roots and leaves, H2O2 accumulation and simultaneous up-regulation of the antioxidative system, which prevented lipid peroxidation even at the highest B concentrations. Thus, P. distans has an efficient root B-exclusion capability and, in addition, B tolerance in shoots is achieved by a well-regulated antioxidant defense system.


Subject(s)
Boron/metabolism , Plant Leaves/physiology , Plant Roots/physiology , Plant Shoots/physiology , Poaceae/physiology , Adaptation, Physiological , Antioxidants/metabolism , Ascorbate Peroxidases/metabolism , Biological Transport , Catalase/metabolism , Glutathione Reductase/metabolism , Hydrogen Peroxide/metabolism , Lipid Peroxidation , Nitrogen/metabolism , Peroxidase/metabolism , Plant Leaves/metabolism , Plant Roots/metabolism , Plant Shoots/metabolism , Poaceae/metabolism , Reactive Oxygen Species/metabolism , Soil/chemistry , Superoxide Dismutase/metabolism , Time Factors
13.
Water Res ; 55: 83-94, 2014 May 15.
Article in English | MEDLINE | ID: mdl-24602863

ABSTRACT

Extremely acidic and saline groundwater occurs naturally in south-western Australia. Discharge of this water to surface waters has increased following extensive clearing of native vegetation for agriculture and is likely to have negative environmental impacts. The use of passive treatment systems to manage the acidic discharge and its impacts is complicated by the region's semi-arid climate with hot dry summers and resulting periods of no flow. This study evaluates the performance of a pilot-scale compost bioreactor treating extremely acidic and saline drainage under semi-arid climatic conditions over a period of 2.5 years. The bioreactor's substrate consisted of municipal waste organics (MWO) mixed with 10 wt% recycled limestone. After the start-up phase the compost bioreactor raised the pH from ≤3.7 to ≥7 and produced net alkaline outflow for 126 days. The bioreactor removed up to 28 g/m(2)/d CaCO3 equivalent of acidity and acidity removal was found to be load dependent during the first and third year. Extended drying over summer combined with high salinity caused the formation of a salt-clay surface layer on top of the substrate, which was both beneficial and detrimental for bioreactor performance. The surface layer prevented the dehydration of the substrate and ensured it remained waterlogged when the water level in the bioreactor fell below the substrate surface in summer. However, when flow resumed the salt-clay layer acted as a barrier between the water and substrate decreasing performance efficiency. Performance increased again when the surface layer was broken up indicating that the negative climatic impacts can be managed. Based on substrate analysis after 1.5 years of operation, limestone dissolution was found to be the dominant acidity removal process contributing up to 78-91% of alkalinity generation, while bacterial sulfate reduction produced at least 9-22% of the total alkalinity. The substrate might last up to five years before the limestone is exhausted and would need to be replenished. The MWO substrate was found to release metals (Zn, Cu, Pb, Ni and Cr) and cannot be recommended for use in passive treatment systems unless the risk of metal release is addressed.


Subject(s)
Bioreactors , Water Pollutants, Chemical/metabolism , Acids , Desert Climate , Environmental Monitoring , Groundwater/analysis
14.
J Exp Bot ; 59(3): 575-83, 2008.
Article in English | MEDLINE | ID: mdl-18252701

ABSTRACT

The present study investigates whether previously acquired boron (B) in mature leaves in white lupin can be retranslocated into the rapidly growing young reproductive organs, in response to short-term (3 d) interrupted B supply. In a preliminary experiment with white lupin in soil culture, B concentrations in phloem exudates remained at 300-500 microM, which were substantially higher than those in the xylem sap (10-30 microM). The high ratios of B concentrations in phloem exudates to those in the xylem sap were close to values published for potassium in lupin plants. To differentiate 'old' B in the shoot from 'new' B in the root, an experiment was carried out in which the plants were first supplied with 20 microM (11)B (99.34% by weight) in nutrient solution for 48 d after germination (DAG) until early flowering and then transferred into either 0.2 microM or 20 microM (10)B (99.47% by weight) for 3 d. Regardless of the (10)B treatments, significant levels of (11)B were found in the phloem exudates (200-300 microM in 20 microM (10)B and 430 microM in 0.2 microM (10)B treatment) and xylem sap over the three days even without (11)B supply to the root. In response to the 0.2 microM (10)B treatment, the translocation of previously acquired (11)B in the young (the uppermost three leaves), matured, and old leaves was enhanced, coinciding with the rise of (11)B in the xylem sap (to >15 microM) and phloem exudates (430 microM). The evidence supports the hypothesis that previously acquired B in the shoot was recirculated to the root via the phloem, transferred into the xylem in the root, and transported in the xylem to the shoot. In addition, some previously acquired (11)B in the leaves may have been translocated into the rapidly growing inflorescence. Phloem B transport resulted in the continued net increment of (11)B in the flowers over 3 d without (11)B supply. However, it is still uncertain whether the amount of B available for recirculation is adequate to support reproductive growth until seed maturation.


Subject(s)
Boron/metabolism , Flowers/metabolism , Lupinus/metabolism , Phloem/metabolism , Plant Leaves/metabolism , Isotopes/metabolism , Xylem/metabolism
15.
Ann Bot ; 96(5): 755-67, 2005 Oct.
Article in English | MEDLINE | ID: mdl-16033777

ABSTRACT

BACKGROUND: Field observations and glasshouse studies have suggested links between boron (B)-deficiency and leaf damage induced by low temperature in crop plants, but causal relationships between these two stresses at physiological, biochemical and molecular levels have yet to be explored. Limited evidence at the whole-plant level suggests that chilling temperature in the root zone restricts B uptake capacity and/or B distribution/utilization efficiency in the shoot, but the nature of this interaction depends on chilling tolerance of species concerned, the mode of low temperature treatment (abrupt versus gradual temperature decline) and growth conditions (e.g. photon flux density and relative humidity) that may exacerbate chilling stress. SCOPE: This review explores roles of B nutrition in chilling tolerance of continual root or transient shoot chills in crop species adapted to warm season conditions. It reviews current research on combined effects of chilling temperature (ranging from >0 to 20 degrees C) and B deficiency on growth and B nutrition responses in crop species differing in chilling tolerance. CONCLUSION: For subtropical/tropical species (e.g. cucumber, cassava, sunflower), root chilling at 10-17 degrees C decreases B uptake efficiency and B utilization in the shoot and increases the shoot : root ratio, but chilling-tolerant temperate species (e.g. oilseed rape, wheat) require much lower root chill temperatures (2-5 degrees C) to achieve the same responses. Boron deficiency exacerbates chilling injuries in leaf tissues, particularly under high photon flux density. Suggested mechanisms for B x chilling interactions in plants are: (a) chilling-induced reduction in plasmalemma hydraulic conductivity, membrane fluidity, water channel activity and root pressure, which contribute to the decrease in root hydraulic conductance, water uptake and associated B uptake; (b) chilling-induced stomatal dysfunction affecting B transport from root to shoot and B partitioning in the shoot; and (c) B deficiency induced sensitivity to photo-oxidative damage in leaf cells. However, specific evidence for each of the mechanisms is still lacking. Impacts of B status on chilling tolerance in crop species have important implications for the management of B supply during sensitive stages of growth, such as early growth after planting and early reproductive development, both of which can coincide with the occurrence of chilling temperatures in the field.


Subject(s)
Acclimatization/physiology , Boron/metabolism , Cold Temperature , Crops, Agricultural/physiology , Nutritional Physiological Phenomena , Crops, Agricultural/radiation effects , Water/metabolism
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