1 Introduction

Finger millet or Mandua or Bird’s foot millet commonly known as ragi (Eleusine coracana (L.) Gaertn.) is an essential small millet crop ranked third in India in area and production and has the pride of place in having the highest productivity among the millets after sorghum and pearlmillet (Saravanapandian et al., 2005). It is a staple food crop in many hilly regions of the country. It is grown both for grain and fodder purposes. The crop is well adapted to very poor and marginal uplands where other crops cannot be grown successfully (AICSMIP, 2008). The cultivated area of finger millet in India is 15.4 lakh ha, production is 2.15 million tonnes with an average productivity of 1 402 kg ha_^-1. In Tamil Nadu, finger millet is the most important traditional millet crop grown over an area of 82 335 ha, with production of 1.61 lakh tonnes and the productivity of 1 955 kg ha_^-1 and provides food and nutritional security to the marginal farmers in the rainfed drylands and hilly tribal areas (Season and Crop Report, 2010). 

Drought adversely affects some of the important physiological, biophysical and biochemical processes of the plants, like chlorophyll destruction, enzymatic activities and protein synthesis. It has been documented that root growth, leaf area development, and osmatic adjustment under stress are some of the guidelines in characterizing the genotypes for stress tolerance in ragi (Blum and Sullivan, 1987). Screening varieties for relative drought tolerance has been attempted by various workers using different physiological and biochemical mechanism in various crops but very limited attempt available in ragi crop. Thus, this experiment was conducted for screening the ragi cultivars under rainfed conditions through the morpho-physiological, root characters and total chlorophyll, Relative Water Content will be taken in to consideration to assess the response of the various ragi entries under rainfed condition.

2 Result and Discussion

2.1 Specific Leaf Weight (SLW), Crop Growth Rate (CGR) and Total Dry Matter Production

Specific Leaf Weight (SLW), a measure of thickness of leaf, has been reported to have a strong positive correlation with leaf photosynthesis in several crops as reported by Bowes et al. (1972). In many crop species, thicker leaves would have more number of mesophyll cells with high density of chlorophyll and, therefore, have a greater photosynthetic capacity than thinner leaves (Craufurd et al., 1999).  Specific Leaf Weight is highly correlated with the development of reproductive organ namely flower and ultimately yield. As observed in the present study, SLW, CGR and TDMP were recorded at 45th, 60th, 75th DAS and at harvest stages. Among the seven cultivars, the highest growth attributes characters were noticed in KRI 009-01 at all the growth stages, which was followed by Paiyur 2 and both are on par with each other. The lowest performance was noticed in CO 15 and GPU 28. Dornhoff and Shibles (1970) presumed that higher SLW might be associated with higher cell surface to volume ratio and hence lower mesophyll resistance to CO2 entry and increase in photoassimilates accumulation in soybean.

2.2 Yield

Table 1 Responses of ragi cultivars under rain-fed conditions on Specific Leaf Weight and Crop Growth Rate at different growth stages

Table 2 Responses of ragi cultivars under rain-fed conditions on TDMP at different growth stages and yield at harvest stage

The variety KRI 009-01 recorded the maximum SLW, CGR and TDMP. The entries KRI 009-01 had maximum yield. Based on this result, the entries of KRI 009-01 was found to be superior over the other entries for tolerance to drought under rainfed conditions.

References

Bowes G.W., Orgen L., and Hageman R.H., 1972, Light saturated photosynthesis rate, RuBp Carboxylase activity and specific leaf weight in soybean grown under different light intensities, Crop Sci., 12: 77-79

http://dx.doi.org/10.2135/cropsci1972.0011183X001200010025x

Craufurd P.C., Wheelee T.R., Ellis R.H., Summer Field R.J., and Williams J.H., 1999, Effect of temperature and water deficit on water use efficiency, carbon isotope discrimination and specific leaf weight in peanut, Crop Sci., 39: 136-142

http://dx.doi.org/10.2135/cropsci1999.0011183X003900010022x

Dornhoff G.M., and Shibles R.M., 1970, Varital differences in net photosynthesis of soybean leaves, Crop Sci., 10: 42-45

http://dx.doi.org/10.2135/cropsci1970.0011183X001000010016x

Saravanapandian P., Masilamani, and Annadurai K., 2008, Indian Journal of Forestry (India), 31(3): 399-404

Blum A. and Sullivan C.Y., 1987, The comparative drought resistance of land races of sorghum and millet from dryland humid regions, Annals of Botany, 57: 835-846

http://dx.doi.org/10.1093/oxfordjournals.aob.a087168