Optimum soil water content for chickpea emergence in heavy-textured soils of north-west Bangladesh

Sowing of chickpea in the heavy-textured soils of north-west Bangladesh with minimum tillage technology aims to increase the timely planting of large areas during a relatively short sowing window before soil water deficit limits germination and emergence. However, the seedbed conditions into which chickpea is sown need to be better quantified, so that limiting factors which affect germination and emergence can be identified. Two of the soil physical characteristics of importance are soil water and aeration. Growth cabinet studies have identified the fastest germination and emergence of chickpea on representative soils for this area at gravimetric water contents of 17-18 %, whilst soil water contents above and below this delayed germination and emergence. Emergence was recorded at soil water potentials between field capacity (-10 kPa) and wilting point (-1500 kPa). Emergence was possible at lower soil water potentials in the finer textured soil, whilst in coarser textured soil, emergence was still possible at higher soil water potentials

Identification of two chickpea multidrug and toxic compound extrusion transporter genes transcriptionally upregulated upon aluminum treatment in root tips

Aluminum (Al) toxicity poses a significant challenge for the yield improvement of chickpea, which is an economically important legume crop with high nutritional value in human diets. The genetic basis of Al-tolerance in chickpea remains unclear. Here, we assessed the Al-tolerance of 8 wild Cicer and one cultivated chickpea (PBA Pistol) accessions by measuring the root elongation in solution culture under control (0 μM Al3+) and Al treatments (15, 30 μM Al3+). Compared to PBA Pistol, the wild Cicer accessions displayed both tolerant and sensitive phenotypes, supporting wild Cicer as a potential genetic pool for Al-tolerance improvement. To identify potential genes related to Al-tolerance in chickpea, genome-wide screening of multidrug and toxic compound extrusion (MATE) encoding genes was performed. Fifty-six MATE genes were identified in total, which can be divided into 4 major phylogenetic groups. Four chickpea MATE genes (CaMATE1-4) were clustered with the previously characterized citrate transporters MtMATE66 and MtMATE69 in Medicago truncatula. Transcriptome data showed that CaMATE1-4 have diverse expression profiles, with CaMATE2 being root-specific. qRT-PCR analyses confirmed that CaMATE2 and CaMATE4 were highly expressed in root tips and were up-regulated upon Al treatment in all chickpea lines. Further measurement of carboxylic acids showed that malonic acid, instead of malate or citrate, is the major extruded acid by Cicer spp. root. Protein structural modeling analyses revealed that CaMATE2 has a divergent substrate-binding cavity from Arabidopsis AtFRD3, which may explain the different acid-secretion profile for chickpea. Pangenome survey showed that CaMATE1-4 have much higher genetic diversity in wild Cicer than that in cultivated chickpea. This first identification of CaMATE2 and CaMATE4 responsive to Al3+ treatment in Cicer paves the way for future functional characterization of MATE genes in Cicer spp., and to facilitate future design of gene-specific markers for Al-tolerant line selection in chickpea breeding programs

Communication and mutual resource exchange in north Florida hermit crabs

The patterns of shell exchange in three species of hermit crabs which overlap in distribution and shell use were observed in the laboratory. Crabs showed no tendency to initiate more exchanges with conspecifics as compared with nonconspecific individuals and there were no specific size dominance effects. Lack of common communicatory patterns between Clibararius vittatus and Pagurus pollicaris was correlated with minimal actual exchange, while Pagurus impressus exchanged with both species and executed patterns in common with both. The pattern of shell exchanges and preferences indicated that, in some cases, both individuals may gain in interspecific exchanges.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46904/1/265_2004_Article_BF00569198.pd

Genotypic variation among chickpea and wild Cicer spp. in nutrient uptake with increasing concentration of solution Al at low pH

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

Soil disturbance levels, soil water content and the establishment of rainfed chickpea: Mechanised seeding options for smallholder farms in north‐west Bangladesh

Optimum soil physical conditions for crop establishment are more likely to occur with mechanised row‐sowing using metered seeding and controlled depth placement of seeds than with broadcast sowing, that is common in many traditional South Asian cropping practices. Establishment success is a limitation for post‐rice crops in medium to heavy textured soils in the Eastern Gangetic Plain because sowing coincides with rapid topsoil drying and increases in soil strength. In addition, due to lack of rainfall in the post‐rice season the crop relies on access to stored soil water during vegetative and reproductive growth to achieve adequate yields. Our aim was to determine whether decreased soil disturbance (from full tillage to zero tillage (ZT) to undisturbed soil (Fallow)) and direct seeding (using small‐scale seeders) could 1) enhance chickpea crop establishment by conserving seedbed soil water and 2) alter crop water use of the water stored in the soil profile. The silt loam soil has an estimated volumetric soil water content (θv) of 34% at field capacity. At sowing, θv in the seedbed was between 25% to 29%. This was adequate for successful chickpea crop establishment, but slightly wetter than optimum for tillage. In the wet soil at sowing, there was evidence of smeared furrow walls and poor soil covering of the seed in the seedbed in strip planting (SP; rotating blades in front of tine) and ZT. Uncovered furrows (in ZT; using a tine opener) and the fallow soil lost more surface soil water (9%, 23 days after sowing) than the seedbeds created with greater levels of soil disturbance. In 2008, grain yield of single‐pass shallow tillage (SPST) was greater than SP but in 2009, grain yields of all one‐pass tillage techniques (ZT, SP, SPST) were greater than in the broadcast seeding in fully tilled soils. The improvement in chickpea yields was attributed to greater plant numbers, early plant vigour and root growth. Chickpea roots were found to 60 cm depth in the soil profile, and soil water content was less than the θv of wilting point to this depth at podding. There is evidence that root growth and plant water uptake occur deeper in these soil profiles to achieve the grain yields > 1,000 kg/ha recorded in this study. Mechanised sowing in rows with small‐scale seeders has the capability to overcome establishment and yield limitations for chickpea on medium to heavy soils in the post‐rice season

Managing sands of the lower Mekong Basin to limit land degradation: A review of properties and limitations for crop and forage production

Land development is rapidly occurring on sand-dominant soils that cover substantial areas of the Lower Mekong Basin (LMB). Sands are at risk of degradation on sloping uplands where agriculture is expanding and on lowland landscapes where intensification of cropping is occurring. Sandstone and granitic geology explain the prevalence of sand-dominant textures of profiles in the LMB. However, the sand terrains in uplands of Cambodia and Southern Laos mostly have not been mapped in detail and the diversity of their edaphic properties is poorly understood. On high-permeability sands, lowland rainfed rice crops are drought-prone, while nutrient losses from leaching are also a risk. Furthermore, waterlogging, inundation and subsoil hardpans are significant hazards that influence the choice of crops and forages for lowland soils. Soil acidity, low nutrient status, hard-setting and shallow rooting depth are significant constraints for crops and forages on sands in the lowlands. Land use change in the lowlands to alternative field crops and forages on sands is contingent on their profitability relative to rice, the amounts and reliability of early wet season rainfall, and the amounts of stored water available after harvesting rice. Low soil fertility and soil acidity are limitations to the productivity of farming systems on the sand profiles in uplands, while erosion, low soil organic matter levels and water balance are concerns for their sustainable use. Site-/soil-specific fertilizer and lime management, land suitability assessment and the use of conservation agriculture principles (minimum tillage and crop residue retention) can overcome some of these constraints

Optimum time of sowing for rainfed winter chickpea with one-pass mechanised row-sowing: An example for small-holder farms in north-west Bangladesh

The time of sowing chickpea (Cicer arietinum L.) in the High Barind Tract of north-west Bangladesh is critical to crop success. To ensure adequate emergence and subsequent crop growth, chickpea relies on residual soil moisture stored in the profile after rice (Oryza sativa L.) cultivated in the preceding rainy season. With the development of mechanised, one-pass minimum tillage sowing, the time between rice harvest and chickpea sowing is decreased, and temperature constraints that limit biomass and/or pod formation and filling may be avoided. Minimum tillage may also limit evaporation from the soil surface compared with traditional, full cultivation procedures. The objective of this study was to identify the optimum sowing time to achieve adequate crop establishment and limit exposure of the chickpea crop to terminal drought and heat stress later in the growing season. Over three experimental seasons, chickpea sowing dates were spread from 22 November to 22 December. Soil water content, crop growth and temperature were monitored to determine the optimum sowing time. Over all seasons and sowing dates, the volumetric soil water content in the seedbed under minimum tillage remained within 17-34%, a range non-limiting for chickpea establishment in glasshouse and field experiments. Late planting (after 10 December) exposed seedlings to low temperatures (35°C), resulting in unfilled pods and depressed grain yield. The preferred sowing time was determined to be 30 November to 10 December to reduce the risk of high temperatures and low soil water content during chickpea reproductive growth causing terminal heat and drought stress, respectively. Mechanised sowing in one operation allows farmers to optimise their time of sowing to match seed requirements for soil water at emergence and may assist farmers to avoid temperature stresses (both low and high) that constrain chickpea vegetative and reproductive growth

Manual for Smallholders' Conservation Agriculture in Rice-Based Systems

...This is the first version of the CA Manual. It is designed to describe the current state of knowledge about the practices that represent CA systems for smallholders in rice-based cropping in Bangladesh..