Evaluation of Drought Tolerance Indices in Bread Wheat (Triticum aestivum L.) Genotypes under Post Anthesis Drought Stress

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1 J. Agric. Technol., 1(1): (2014) ISSN: Evaluation of Drought Tolerance Indices in Bread Wheat (Triticum aestivum L.) Genotypes under Post Anthesis Drought Stress Manmatha Hansda 1 and Saikat Das 2 1,2 Uttar Banga Krishi Viswavidyalaya, Pundibari, Coochbehar , West Bengal Drought indices which provide a measure of drought based on loss of yield under drought conditions in comparison to normal conditions have been used for screening drought tolerant genotypes since long. These indices are either based on drought resistance or susceptibility of genotypes (Fernandez 1992). In the present study drought tolerance in fourty nine genotypes of wheat was estimated based on these different indices by screening the genotypes under both irrigated and rainfed condition. Beside grain yield, genotypes were also evaluated for other growth and reproductive parameters like germination (%), days to heading (75%), days to physiological maturity, plant height, tillers per meter, grains per spike, spike length, test weight, etc. The result indicated significant differences among genotypes for most of the characters under study except for spike length and test weight. Evaluation of correlation coefficients also exhibitted positive and significant correlation (r 2 = 0.86) between grain yield under non-stress (Yp) and stress (Ys) environments. Highest Stress tolerance (TOL) and Stress Susceptibility Index (SSI) value were related to genotypes HI 1579, KYP 0826, KLP 3129, NIAW 656, RAJ 4254 indicating that these genotypes had higher grain yield reduction under rainfed condition and highest drought sensitivity. AKAW 3717, AKAW 4705, NI 5439, KLP 1042 were the most tolerant genotypes based on TOL and SSI values with their low quantity as indication towards tolerant genotypes. Ranking of genotypes in respect to all drought tolerance indices revealed that genotype KLP 3129, NIAW 656 and HI 1579 had the best mean rank. Most appropriate index to select drought tolerant genotypes were found to be STI, MP, GMP, HAM,YI which had a high correlation with grain yield under both irrigated and drought condition. After grouping of genotypes based on their production under irrigated and drought condition, it was found that genotypes like AKAW 3717, NIAW 656, VL 952 and KLP 1043 had high production potential under both drought and irrigated condition while genotypes like HI 1579, KYP 826, KLP 3129 were suitable for only irrigated condition. Similarly, genotypes like KLP 1045and AKAW 4730 had a high production potential only under drought stress condition. So, these genotypes may be used in future breeding programme depending upon the suitability of environmental condition. Genotypes like GW , RAJ 4083, RAJ 4168, AKAW 4705 and KLP 3077 had poor production potential under both condition. So these lines are not suitable for any of these environments. Keywords: Drought Indices, Rainfed Stress, Wheat, Yield World food production is limited primarily by environmental stresses. It is very difficult to find stress free areas where crops may approach their potential yield. Abiotic environmental factors are considered to be the main source (71%) of yield reductions (Boyer, 1982). Drought is one of the most common environmental stresses that affects growth and development of plants through alterations in metabolism and gene expression (Leopold, 1990). Water stress experienced by a wheat crop during growth is known to have cumulative effects expressed as a reduction in total biomass compared to the well watered 36 potential. Better performance of the crop depends upon availability of water during tillering, anthesis and grain formation stages. Water stress at anthesis reduces pollination and thus less grains per spike which results in the reduction of grain yield (Nazir et al., 1987). Adequate water at or after anthesis period not only allows the plant to increase photosynthetic rate but also increases grain filling duration (Zhang et al., 1998), thus enhancing grain size and ultimately cause higher grain yield (Gallagher and Biscoe, 1978).

2 Evaluation of Drought Tolerance Indices in Bread Wheat (Triticum aestivum L.) As loss of yield is the main concern for the crop plants from agricultural point of view, plant breeders emphasize on yield performance under moisture stress condition. Drought indices which provide a measure of drought based on loss of yield under drought conditions in comparison to normal conditions have been used for screening drought tolerant genotypes (Mitra, 2001). These indices are either based on drought resistance or susceptibility of genotypes (Fernandez, 1992). Drought resistance is defined by Hall (1993) as the relative yield of genotype compared to other genotypes subjected to the same drought stress. Drought susceptibility of a genotype is often measured as a function of the reduction in yield under drought stress (Blum 1988). Rosielle and Hamblin (1981) defined stress tolerance (TOL) as the differences in yield between the stress and non stress environments and mean productivity (MP) as the average yield under stress and non stress environments (Hamblin1981). Fischer and Maurer (1978) proposed a Stress Susceptibility Index (SSI) while, Fernandez (1992) defined a new advanced index (STI = Stress Tolerance Index), which can be used to identify genotypes that produce high yield under both stress and non stress conditions. Other yield based estimates of drought resistance are geometric mean (GM), Mean productivity (MP) and TOL. The Geometric mean is often used by breeders interested in relative performance since drought stress can vary in severity in field environment over years (Kelly, 1988). In the present study drought tolerance in fourty nine genotypes of wheat was estimated based on these different indices by screening the genotypes under both irrigated and rainfed condition. MATERIALS AND METHODS The present investigation was conducted during rabi season of crop season at the University Farm of Uttar Banga Krishi Viswavidyalaya, Pundibari, Cooch Behar which is situated at N latitude, E longitude with an altitude of 43 m above the mean sea level. Field experiment was conducted at sandy loam soil with slightly acidic ph (5.3) having moderate fertility status (N: 117, P 2 O 5 : 14.98, K 2 O: kg - ha.). The experimental detail is as follows: Date of sowing : 15 th November, 2011 Design of the experiment block design No. of genotypes : 49 No. of replication : 2 Type of sowing Length of the row Distance between rows : Randomized : Line Sowing : 2.0 m : 30 cm Plot size (length x breadth) : 2.0 m x 0.6 m Irrigatio : One set with full irrigation and another without any irrigation Fertilizer : N-120 Kg ha -1 P-60 Kg ha -1, K-40 Kg ha -1 (basal) Date of harvesting : 10 th April, 2012 After physiological ripening, grain yield was obtained and drought tolerance indices were estimated by using the formula as stated in Table 1. Table 1: Estimation of Different Drought Toleranance Indices along with their Formula Index Formula Reference Stress Tolerance TOL = Yp Ys Rosielle and Hamblin [1981] Mean Productivity MP = (Yp + Ys) / 2 Rosielle and Hamblin [1981] Geometric Mean Productivity GMP = (Yp * Ys) 0.5 Fernandez [1992] Stress Susceptibility Index SSI = [(1 (Ys / Yp)] / SI Fischer and Maurer [1978] (Stress Index) SI = 1 ( Ỹs / Ỹp ) Stress Tolerance Index STI = (Yp * Ys) / (Ỹp) 2 Fernandez [1992] Harmonic Mean HAM = [2* (Yp * Ys)] /(yp + Ys) Kristin et al., [1997] Yield Index YI = Ys / Ỹs Lin et al., [1986] YSI = Ys / Yp Bouslama and Schapaugh [1984] Y p and Y s: Grain yield of each genotype under non-stress and stress conditions, respectively Ỹ p and Ỹ s : Mean grain yield of all genotypes under non-stress and stress conditions, respectively 37

3 Journal of Agriculture and Technology Beside grain yield, genotypes were also evaluated for other growth and reproductive parameters like germination (%), days to heading (75%), days to physiological maturity, plant height, tillers per meter, grains per spike, spike length, test weight, etc. RESULTS AND DISCUSSION The result showed that there were significant differences among genotypes for most of the characters under study except for spike length and test weight (Table 2). Effect of drought stress was also significant for all the traits except germination%. Interaction component varied significantly for traits like heading and maturity duration, plant height, tillers meter -1, grains spike -1, yield plot -1, etc. Mean vales sowed that genotypes like HI 1579 with 500 g plot -1 had the highest grain yield while AKAW 4705 and Raj 4083 with 150 g plot -1 were the lowest yielder under non stress condition. Under rainfed environments, genotype AKAW 3717 with 395 g plot -1 and GW with 155 g plot -1, respectively had the highest and lowest grain yields, too. Evaluation of correlation coefficients showed that there was a positive and significant correlation (r 2 = 0.86) between grain yield under non-stress (Yp) and stress (Ys) environments (Table 5). Calculation of tolerance indices showed that highest Stress tolerance (TOL) and Stress Susceptibility Index (SSI) value were related to genotypes HI 1579, KYP 0826, KLP 3129, NIAW 656, RAJ 4254 indicating that these genotypes had higher grain yield reduction under rainfed condition and highest drought sensitivity (Table 3 and 4). AKAW 3717, AKAW 4705, NI 5439, KLP 1042 were the most tolerant genotypes based on TOL and SSI values with their low quantity as indication towards tolerant genotypes. It seems TOL had succeeded in selection of genotypes with high yield under drought stress, but had failed to select genotypes with proper yield under both environments. It also, seems if a genotype has high grain yield under both non-stress and stress conditions but has high variation in its yields between these two conditions, it is not selected as drought tolerant genotype by SSI. Table 2: Analysis of Variance of 49 Bread Wheat Genotypes for Different Growth and Yield Attributes under Both Drought and Irrigated Condition Sources df Germination (%) Days to Heading (50%) Days to Maturity Plant Height (cm) Grains Per Spike Spike Length (cm) Test Weight (g) Grain Yield Per Plot (g) Mean Square Tillers Per Meter Environment ** * * * ** * ** * ** ** * Error Genotype ** ** ** ** ** 72.75** ** GxE ** 37.45** ** 96.19** 28.58** ** Error CV *,**= Significant at 5% and 1% levels respectively Table 3: Mean Values of Grain Yield under Non Stress (Y p ) and Stress Condition (Y s ) and Different Drought Tolerance Indices in 49 Bread Wheat Genotypes Genotypes Irrigated Drought TOL MP GMP SSI STI HAM YI YSI (Y p) (Y s) 56AKAW AKAW AKAW AKAW C GW GW GW Gw Table 3 (Contd.) 38

4 Evaluation of Drought Tolerance Indices in Bread Wheat (Triticum aestivum L.) Table 3 (Contd.) GW GW GW HI HI HI HI K KLP KLP KLP KLP KLP KLP KLP KLY KLY KYP NI NIAW NIAW NWL RAJ RAJ GW RAJ RAJ RAJ RAJ RAJ RS RS VL VL WH WS WS WS WS WSM Table 4: Ranking of 49 Wheat Genotypes in Respect to Different Drought Tolerance Indices Genotypes TOL MP GMP SSI STI HAM YI YSI Mean AKAW AKAW AKAW AKAW C GW GW GW GW GW GW GW HI HI HI Table 4 (Contd.) 39

5 Journal of Agriculture and Technology Table 4 (Contd.) HI K KLP KLP KLP KLP KLP KLP KLP KLY KLY KYP NI NIAW NIAW NWL RAJ RAJ GW RAJ RAJ RAJ RAJ RAJ RS RS VL VL WH WS WS WS WS WSM AKAW 3717, HI 1579, KLP 3129, NIAW 656, VL 952 were found to be the tolerant genotypes based on Mean Productivity (MP), Geometric Mean Productivity (GMP), Stress Tolerance Index (STI), Harmonic Mean(HAM) and Yield Index (YI) with their high value as indication towards tolerance(table 3 and 4). Based on these current indices GW , RAJ 4083, RAJ 4168 and AKAW 4705 were the most sensitive genotypes. In terms of Yield Stability Index (YSI) genotype AKAW 3717 and AKAW 4705 were having the highest value while genotype HI 1579 and RAJ 4254 had lowest value indicating highest and lowest stability respectively. The results showed that, the highest positive and significant correlations with Yp were observed among MP, GMP, STI and HAM (Table 5). The same results obtained among Ys and MP, GMP, STI and HAM too. The highest correlation (r 2 = 1.00) was observed between Ys and YI and also between GMP and MP. The correlations of SSI (r2 = - 0.3) with Ys was negative and significant (p < 0.05). There was a positive and significant correlation between TOL and SSI (r 2 = 0.86). There were also, positive and significant correlations among MP, GMP, STI, HAM and YI (p < 0.01). 40

6 Evaluation of Drought Tolerance Indices in Bread Wheat (Triticum aestivum L.) Table 5: Correlation Coefficient among Grain Yield under Non-stress (Y p ) and Stress (Y s ) Conditions and Different Drought Tolerance Indices in 49 Genotypes of Bread Wheat Indices Y p 1.00 Y s 0.86** 1.00 TOL 0.64** MP 0.97** 0.96** 0.44** 1.00 GMP 0.96** 0.97** 0.41** 1.00** 1.00 SSI * 0.86** STI 0.96** 0.96** 0.42** 0.99** 0.99** HAM 0.95** 0.96** 0.40** 0.99** 0.99** ** 1.00 YI 0.86** 1.00** ** 0.97** -0.30* 0.96** 0.96** 1.00 YSI * -0.86** ** * 1.00 Ranking of genotypes in respect to all drought tolerance indices revealed that genotype KLP 3129, NIAW 656 and HI 1579 had the best mean rank (Table 4). The result also demonstrated that most appropriate index to select drought tolerant genotypes were STI, MP, GMP, HAM,YI which had a high correlation with grain yield under both irrigated and drought condition. Similar results were reported by Zeynali et al., (2004) and Karimizadeh and Mohammadi (2011). Fernandez (1992) classified genotypes according to their production under non-stress and stress conditions to four groups: genotypes with high production under both conditions (Group A), genotypes with high production only under non stress conditions (Group B), genotypes with high production only under stress conditions (Group C) and genotypes with weak production under both conditions (Group D). When the present genotypes were grouped into the above mentioned four categories based on their production under irrigated and drought condition, it was found that genotypes like AKAW 3717, NIAW 656, VL 952 and KLP 1043 had high production potential under both drought and irrigated condition while genotypes like HI 1579, KYP 826, KLP 3129 were suitable for only irrigated condition. Similarly, genotypes like KLP 1045and AKAW 4730 had a high production potential only under drought stress condition. So, these genotypes may be used in future breeding programme depending upon the suitability of environmental condition. Genotypes like GW , RAJ 4083, RAJ 4168, AKAW 4705 and KLP 3077 had poor production potential under both condition. So these lines are not suitable for any of these environments. 41 REFERENCES Blum A Plant Breeding for Stress environments.crc Press Florida 212 Boyer JS Photosynthesis at low water potentials. Phil Trans Royal Soc. 273: Fernandez GCJ Effective selection criteria for assessing stress tolerance. In: Kuo CG (ed), Proceedings of the international symposium on adaptation of vegetables and other food Crops in temperature and water stress. Public Tainan Taiwan Fischer RA, Maurer R Drought resistance in spring wheat cultivars. I. Grain yield responses. Aust J Agric Res. 29: Gallagher JN, Biscoe PV Radiation absorption, growth and yield of cereals. J Agril Sci Cambridge. 91: Hall AE Is dehydration tolerance relevant to genotypic differences in leaf senescence and crop adaptation to dry environments? In: Plant Responses to cellular dehydration during environmental stress, TJ Close, EA Bray (eds). pp Karimizadeh R, Mohammadi M Association of canopy temperature depression with yield of durum wheat genotypes under supplementary irrigated and rainfed conditions. Australian J Crop Sci. 5(2): Leopold AC Coping with desiccation. In: Alscher RG and Cumming JR. Stress responses in plants: Adaptation and Acclimation Mechanisms. Wily-Liss, New York. pp

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