Root traits, nutrient uptake, multi-location grain yield and benefit–cost ratio of two lentil (Lens culinaris, Medikus.) varieties

Abstract

Lentil is a protein-rich pulse, grown mainly in developing countries as a rain-fed crop in nutrient-poor soils. Hence, the importance of root traits for efficient capture of soil nutrients and water can be crucial to its economical yield. Little is known about the lentil root system and even less about its relationship to grain yield. We compared the root system of two Bangladeshi lentil varieties, Barimasur-3 (BM-3) and Barimasur-4 (BM-4), in a pot experiment and related it to their multi-location grain yield in the fields. BM-4 maintained faster root development both at an early growth stage (20 days after sowing) and at flowering (60 days) compared to BM-3. The roots of BM-4 penetrated the 25 cm depth of the soil profile after 19 ± 1 days and while those of BM-3 took 24 ± 2 days to reach the same depth. The roots of BM-4 were covered with denser (26 ± 3 mm )1 ) and longer (0.48 ± 0.11) root hairs than BM-3 (density 17 ± 2 mm )1 , length 0.32 ± 0.09 mm). The differential presence of root hairs increased the effective length of root system of BM-4 by 12 times and that of BM-3 by five times. The lentil varieties did not differ in their ability to induce pH change and acid phosphatase activity in rhizosphere. In the pot experiment, the uptake of macro-nutrients (K, P, Ca, and Mg) as well as micro-nutrients (Fe, Mn, Zn, Cu, B and Mo) by BM-4 was significantly higher, compared to BM-3. The varieties produced the same amount of shoot biomass. At five of six agro-ecological distinct field locations in Bangladesh, BM-4 gave significantly higher (10-20%) grain yield than BM-3. Linked with the higher grain yield, the benefit-cost ratio (BCR) of BM-4 was 3.14 and that of BM-3 were 2.62, indicating that BM-4 provided better return per unit investment, compared to BM-3, supported by the better root morphology and higher nutrient uptake. This may be one of the reasons supporting the popularity and preferred adoption of BM-4 among the Bangladeshi farmers, who grow lentil mainly on nutrient-poor soils. The results indicate the benefits of selection and breeding for superior root traits for better agro-economics.

Abiotic Stresses

“…Variation in tolerance to boron deficiency has been identified in lentil, with germplasm from South Asia exhibiting the least symptoms and those from the Middle East exhibiting the most severe symptoms (Srivastava et al 2000). Gahoonia et al (2005) found that lentil lines exist with different root morphologies that may be better able to scavenge micronutrients such as B from the soil and give 10-20% yield increases. There is increasing evidence that the same genetic mechanisms are likely to control tolerance to both boron deficiency and toxicity, predominantly boron exclusion Erskine 2000, Dannel et al 2002).…”

Opportunities to improve the seasonal dynamics of water use in lentil (Lens culinaris Medik.) to enhance yield increase in water-limited environments

“…High genetic variation has been reported for root traits such as taproot length, lateral root number, total root length, and total root weight for lentil germplasm from different origins [13,14,25,26,31,42]. The high heritability estimates that were reported by these authors indicate the feasibility of making use of this genetic variability for the development of drought-adapted cultivars.…”

“…Lentil is an annual herbaceous plant with indeterminate growth exhibiting high variation in its growth habit: single stem, erect, semi-erect, compact growth or much-branched low bushy forms [13,14,31,42]. Developmental plasticity can involve one or all of these plant characteristics.…”

“…They found correlations between the individual traits and achieving a higher yield under drought conditions. More recently, Mishra et al [32] found correlations between chlorophyll content and stability, increased accumulation of osmotically active solutes, soluble sugars and proline, lower H 2 O 2 and malondialdehyde (MDA) contents, and lower carbon isotope discrimination (ΔC 13 ) values and drought resistance in lentil. This study was conducted on a very limited number of genotypes (two) and drought was imposed at three different phenological stages (vegetative, flowering initiation and pod development).…”

Quantitative evaluation of lentil (Lens culinarisMedikus.) germplasm under low-input acidic upland soil conditions of North-East India

“…The knowledge of degree of association of various agromorphological characters with yield helps in designing effective breeding strategies for crop improvement. Moreover, traits such as root and shoot biomass have been reported to be associated with yield under drought and poor soils [4][5][6]. Therefore, this study was undertaken to understand and identify genotypes with high yield under low moisture and low input acidic soil conditions.…”