Data assessing genotypic variations in selected traditional rice landraces of Jeypore tract of Odisha, India based on photosynthetic traits

Variations in photosynthetic characteristics and dry matter accumulation were investigated in thirty selected rice (Oryza sativa L.) landraces from Jeypore tract of Odisha, India to find the possibility of their use in crop improvement programs. Leaf gas exchange measurements, photosystem (PS) II activity and leaf pigment estimates were conducted at the flowering stage. Significant differences were noticed in the CO2 photosynthetic rate (PN), stomatal conductance (gs), transpiration rate (E), internal CO2 concentration (Ci), water use efficiency (WUE) and carboxylation efficiency (CE) among the landraces. In addition, significant variation was observed in leaf chlorophyll content, PS II activity and dry matter accumulation (DMA). Further, multiple correlations between photosynthetic characteristics and other physiological traits revealed that leaf photosynthesis was not significantly influenced by PS II photochemical activity, leaf area and pigment contents but it was regulated by stomatal conductance, water use efficiency and carboxylation efficiency. Taken together, data presented here shows that some of the landraces had superior photosynthetic traits along with better DMA under prevailing environmental condition and can be used for future crop improvement programs aimed for an increase of leaf photosynthesis in rice.


a b s t r a c t
Variations in photosynthetic characteristics and dry matter accumulation were investigated in thirty selected rice (Oryza sativa L.) landraces from Jeypore tract of Odisha, India to find the possibility of their use in crop improvement programs. Leaf gas exchange measurements, photosystem (PS) II activity and leaf pigment estimates were conducted at the flowering stage. Significant differences were noticed in the CO 2 photosynthetic rate (P N ), stomatal conductance (g s ), transpiration rate (E), internal CO 2 concentration (Ci), water use efficiency (WUE) and carboxylation efficiency (CE) among the landraces. In addition, significant variation was observed in leaf chlorophyll content, PS II activity and dry matter accumulation (DMA). Further, multiple correlations between photosynthetic characteristics and other physiological traits revealed that leaf photosynthesis was not significantly influenced by PS II photochemical activity, leaf area and pigment contents but it was regulated by stomatal conductance, water use efficiency and carboxylation efficiency. Taken together, data presented here shows that some of the landraces had superior photosynthetic traits along with better DMA under prevailing environmental

Data
The dataset contains tables and figures on photosynthetic traits of traditional rice landraces of Jeypore tract of Odisha, India. Fig. 1 represents the cluster analysis showing the relationship among traditional landraces of Jeypore tract of Odisha based on leaf photosynthetic traits using Bray Curtis similarity index. Fig. 2 represents scatter graph of different traditional rice landraces and showed that rice landraces 'Basubhoga' was most divergent variety followed by 'Dangarbasumati' and 'Tulasiganthi'. List of selected traditional rice landraces with their characteristic feature and habitat type from Jeypore tract of Odisha are described in Table 1. Variations in leaf photosynthetic parameters, leaf pigments and dry matter accumulation in different traditional rice landraces was presented in Table 2. Different chlorophyll fluorescence parameters such as Fo, Fm Fv/Fm, qP and NPQ were presented in Table 3. Significant variation of SPAD index was observed among studied landraces (Table 3).
Multiple correlation analysis was performed between leaf gas exchanges parameters with other physiological traits ( Table 4). The results showed that the rate of photosynthesis (P N ) was not Our data depicts the relationship between leaf photosynthetic parameters and other physiological traits which is highly important to understand the importance of the landraces with respect to quality traits. The data presented can be a benchmark in future crop improvement programs aimed for improving leaf photosynthesis in rice.  significantly influenced by leaf pigments (Chl and carotenoid contents) and leaf area. A strong positive correlation between P N with gs, CE and WUE (r ¼ 0.509**, 0.579** and 0.544** respectively, P < 0.01) was observed whereas, leaf P N was negatively correlated with Ci (r ¼ À0.245*, P < 0.05).

Plant material and growth condition
The study was conducted by taking thirty selected traditional rice landraces from Jeypore tract of Odisha, India. The detail characteristics of the studied landraces are presented in Table 1. All the landraces were sown directly in earthen pots (30 cm in diameter) containing two kg of farm soil and farmyard manure (3:1) in the campus of Central University of Orissa, Koraput, India (82 44ʹ 54ʹʹ E to 18 46ʹ47ʹʹ N, 880 m above the mean sea level and average rain fall of 1500 mm). After germination, the seedlings were thinned and five plants per pot were maintained. Each pot was supplied with 190 mg single super phosphate (P 2 O 5 ) and 50 mg murate of potash (K 2 O). N-fertilizer in the form urea at 1 g per pot was applied trice after 10, 30 and 50 days of sowing. Each landraces was planted in three pots and each pot was treated as separate replications. Plants were regularly irrigated with tap water and subjected to natural solar radiation, with daily maximum photosynthetic photon flux density, air temperature and relative humidity being about 1280±20 m mol m À2 s À1 , 35.6 ± 2 C and 65e70%,  respectively throughout the experiment. All the measurements were performed three times during flowering stage.

Measurement of leaf gas exchange and chlorophyll fluorescence
The leaf gas exchange parameters were measured between 10 and 12 h on fully matured leaves of each plant using an open system photosynthetic gas analyzer under normal ambient environmental condition. The fully matured 2nd and 3rd leaf from each plant were selected and kept inside the chamber under natural irradiance until stable reading was recorded. The measurements were carried out at 32±2 C, 60e70% relative humidity, 1014 ± 38 mmol m À2 s À1 photosynthetic active radiation, 370 mmol CO 2 m À2 s À1 and 21% O 2 .
Different chlorophyll fluorescence parameters like minimal fluorescence (Fo), maximal fluorescence (Fm), variable fluorescence (Fv ¼ Fm-Fo) and maximum photochemical efficiency of PS II (Fv/Fm) was measured in 20 min dark-adapted leaves. In light adapted leaves at a PPFD of 400 mmol m À2 s À1 (for 15 min) steady state fluorescence yield (Fs), maximal fluorescence (Fmʹ) after 0.8 s saturating white light pulse and minimal fluorescence (Foʹ) were measured when actinic light was turned off. Quenching value due to non-photochemical dissipation of absorbed light energy (NPQ) and the coefficient for photochemical quenching (qP) was also calculated [4]. Table 3 Variation in leaf chlorophyll fluorescence parameters in traditional rice landraces. Data are the mean of three replications ± standard deviation. Means followed by a common letter in the same column are not significantly different at the 5% level by Fisher's least significance difference (LSD) test.

Measurement of SPAD chlorophyll index, flag leaf area and dry matter accumulation
SPAD chlorophyll index was measured on the fully expanded leaf of 5 different plants using an SPAD 502 chlorophyll meter on the intensity of light transmitted 650 nm [5]. The total chlorophyll and carotenoid were measured spectro-photometrically by taking absorbance at 663 nm, 645 nm and 470 nm. The Chl and carotenoid content were calculated using the equation of Arnon [6] and Lichtenthaler and. Wellburn [7].
Flag leaf area (LA) was measured in each plant by taking the length and breadth of leaf and calculated by the using the formula: Leaf area (cm 2 ) ¼ 0.67 x length x width The dry matter accumulation (DMA) was calculated by taking the fresh and dry weight of two different plants in each replication by the following formula Dry matter accumulation (%) ¼ (Dry weight / Fresh weight) Â 100

Statistical analysis
Differences between various parameters were compared by one way analysis of variance (ANOVA) using CROPSTAT (International Rice Research Institute, Philippines) software. The statistical significance of mean of parameters was determined by performing the Fisher's least significance difference (LSD) test. The cluster analysis was carried out by using Bray-Curtis similarity index using PAST-3 (Palaeontological Statistics) software.