Variability of root length density and its contributions to seed yield in chickpea (Cicer arietinum L.) under terminal drought stress

Abstract

The importance of root systems in acquiring water has long been recognized as crucial to cope with drought conditions. This investigation was conducted to: (i) evaluate the variability on root length density (RLD) of chickpea in the vegetative growth stage; (ii) estimate the effect of RLD on seed yield under terminal drought conditions; and (iii) set up a procedure to facilitate the screening of chickpea genotypes with large RLD. Twelve diverse chickpea genotypes were grown in tall PVC cylinders with two different soil water treatments in 2000 and 2001, and in field under water deficit conditions during 2000/2001 and 2001/2002. In field trials, the mean RLD at 35 days after sowing showed a significant positive correlation with seed yield in both years. Similarly, the RLD in the 15-30 cm soil depth had significant positive effects to the seed yield in both years. The importance of the root trait was particularly relevant in 2001/2002, a more severe drought year, when the RLD in deeper soil layer, 30-60 cm depth, showed a significant positive relationship with seed yield. Also, the RLD at deeper soil layer, 30-60 cm depth, was higher in 2001/2002 than in 2000/2001, in particular in tolerant genotypes. The PVC cylinder trials were set up to facilitate the screening of chickpea genotypes with large RLD. RLD of plants grown in cylinders with 70% field capacity was correlated with RLD in the field trials (r = 0.731; p = 0.01). This work highlights the importance of roots in coping with terminal drought in chickpea. The cylinder system offers a much easier procedure to screen chickpea genotypes with large RLD.

Traits of relevance to improve yield under terminal drought stress in chickpea (C. arietinum L.)

“…Under terminal drought, total root biomass of chickpea at an early stage of growth was shown to contribute to yield at maturity in a previous work, particularly by maximizing transpiration over evaporation of water stored into the surface layers (15 to 30 cm) of the soil profile (Kashiwagi et al, 2006a).…”

Improving Drought-Avoidance Root Traits in Chickpea (Cicer arietinumL.) -Current Status of Research at ICRISAT

“…Tall PVC cylinder system was optimized for use to estimate the chickpea root growth since the rooting profi le can not be estimated in shallow pot-grown plants. When the plants were grown in PVC cylinders 18 cm in diameter and 120 cm in height, fi lled with a sand-vertisol mixture containing a soil moisture equivalent to 70% field capacity, the extracted root biomass was demonstrated to be signifi cantly correlated to the ones extracted from the field (r = 0.62, p < 0.05) (Kashiwagi et al, 2006). With this system, the sampling effi ciency could be improved dramatically up to about 25 profiles worker -1 day -1 .…”

“…Under waterlimited receding soil moisture conditions, the root system that can extract relatively more water from deeper soils and/or absorb water relatively rapidly (thereby maximizing transpiration over evaporation) can increase total water transpired. Increased transpiration is not only expected to increase the total biomass productivity but also improves the harvest index (Passioura, 1977(Passioura, , 1994Kashiwagi et al, 2006). In several crops, such as common bean (White and Castillo, 1990), groundnuts (Wright et al, 1991) and soybean (Cortes and Sinclair, 1986), deep rooting has been demonstrated to have positive effects on seed yield through improved transpiration.…”

“…One genotype, ICC 4958, that exhibited the best performance not only in field trials at ICRISAT but also at several other locations in India and in the Mediterranean type climate at Syria, had higher root biomass (ICARDA, 1989;Saxena et al, 1993;Krishnamurthy et al, 1996;Ali et al, 1999Ali et al, , 2005. Subsequently, in a field experiment at ICRISAT with 12 diverse chickpea germplasms, including ICC 4958, it was shown that a prolific root system, especially at the 15-30 cm soil depth, contributed positively to the seed yield under moderate terminal drought intensity and a deeper root system was shown to contribute to improved yield under severe terminal drought conditions (Kashiwagi et al, 2006). Also in a cool-temperate sub-humid climate of New Zealand, the importance of surface soil horizons (0-30 cm) in providing major water requirements of kabuli chickpeas and the ability of chickpea to draw water from depths below 60-cm have been clearly shown (Anwar et al, 2003).…”

Morpho-Anatomical Changes in Roots of Chickpea (Cicer arietinum L.) under Drought Stress Condition

“…Reduction in cortical cell size and number, lignification of epidermal and exodermal cells and layering of sclerenchymatous cells in neighbour of cortical cells are due to the deposition of lignin, and suberins is one of another modifications under water deficit condition [13]. Drought tolerant cultivars tend to have a greater root biomass, i.e., a greater root-to-shoot ratio and deeper root profiles in common beans and pea [14], cowpea [15], soy bean, pea and chickpea [16]. A high ratio of deep root weight to shoot weight was also found to maintain high plant water potentials and had a positive effect on yield under stress [17].…”