AGRICULTURAL RESEARCH COMMUNICATION CENTRE

www.arccjournals.com / indianjournals.comAgric. Sci. Digest., 33 (3) : 172 - 177, 2013DOI- 10.5958/j.0976-0547.33.3.002

EFFECT OF SEED HARDENING AND PELLETING ON SEED QUALITY ANDPHYSIOLOGY OF RICE IN AEROBIC CONDITION

M. Prakash, G. Sathiya Narayanan* , B. Sunil Kumar and A. Kamaraj

Department of Genetics and Plant Breeding, Faculty of Agriculture,Annamalai University, Annamalai Nagar- 608 002, India

Received: 30-09-2012 Accepted: 15-04-2013

ABSTRACTThe present study was conducted to identify rice varieties suitable for aerobic agriculture and to

formulate the seed hardening and pelleting treatment that can be recommended for better cropgrowth and establishment under aerobic condition. The seeds of four rice varieties viz., ADT 43,ADT 38, ADT 36 and ADT 39 were treated with KCl, KH2PO4, Thiourea and CaCl2, @ 1.0 % andsubsequently pelleted with pongam (Pongamia glabra) leaf powder @ 200g/kg, along with a control.The physiological parameters viz., leaf area, leaf photosynthetic rate, transpiration rate, stomatalconductance, intercellular CO2 concentration, root dry weight and seed quality parameters wererecorded. Among the varieties tested, ADT 43 was found more suitable for aerobic agriculture and,even though all the treatments performed better as compared to control, the seeds hardened withKCl (1%) followed by pelleting with pongam leaf powder @ 200 g kg-1 recorded higher physiologicalparameters and seed yield and better seed quality.

Key words: Photosynthesis, Rice, Seed hardening.

INTRODUCTIONRice (Oryza sativa L.) is the prime source of

food for nearly half of the world’s population (Kumaret al., 2008), contributing to 43% of total food grainproduction and 46% of total cereal production inIndia and obviously, it plays a vital role in the nationalfood grain supply. It has been estimated that demandfor rice in 2025 will be around 140 million tonnes(Singh, 2004). Rice, the biggest water using crop inAsia is being threatened by water crisis, worldwideparticularly in India. Water use can be reduced inaerobic rice and it requires either development ofnew cultivars with moderate drought tolerance andhigh harvest index or identifying an existing varietywith less water requirement and increasedphysiological manipulation for imparting droughttolerance.

Aerobic rice is a new concept of growingrice in non-puddled aerobic condition which maybe helpful in solving the problems of drought andlimited water. Direct seeding could be an attractivealternative to the traditional transplanting culture(Balasubramanian and Hill, 2002) but poor

Corresponding Author’s e-mail: sathiyaa2005@yahoo.com

germination and uneven crop stand and high weedinfestation are the main constraints to the adoptionof direct seeded rice (Du and Tuong, 2002). Seedvigour enhancement treatments (priming, hardening,humidification, growth regulators and dry heattreatments) have proven to be very effective toachieve rapid and uniform seed germination in fieldcrops including rice (Farooq et al., 2005), wheat(Basra et al., 2002) and maize (Afzal et al., 2002).

Seed priming/hardening is a commonpractice followed to enhance seed performance withrespect to rate and uniformity of germination (DeLespinay et al., 2010). Seed pelleting is the easierand commonly applicable technique in direct sowncrops which need initial vigour for sustained cropgrowth and development. Pelleting helps to pellet withsuch materials that supplies not only nutrients butalso protects the crop from pests and diseases.Hence, an investigation was carried out to identifysuitable variety and seed hardening and/or pelletingtreatment that can be used for aerobic agriculture.

MATERIALS AND METHODSThe present investigation was carried out in

two experiments viz., 1. Laboratory experiment

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conducted to identify the variety hardening andpelleting treatments and 2. Field experiment toconfirm the variety suitable for aerobic agricultureby identifying the best hardening and pelletingtreatments which will help for enhanced vigour andestablishment. The laboratory experiment wasconducted with four commonly cultivated varietiesviz., ADT 43, ADT 38, ADT 36 and ADT 39 withthe seed hardening, pelleting and both hardeningand pelleting treatments. Genetically and physicallypure seeds of ADT 43, ADT 38, ADT 36 and ADT39 were obtained from the Tamil Nadu RiceResearch Institute (TRRI), Aduthurai, which formedthe basic material for the study. The experimentswere conducted at the Department of Genetics andPlant breeding, Faculty of Agriculture. AnnamalaiUniversity, Annamalai Nagar, Tamil Nadu, India,during the year 2008-2010 with the followingtreatments viz., To- Control, T1-1% KCL, T2-1%KH2PO4, T3-100 ppm Thiourea, T4-1% CaCl2, T5-1%KCl + Pongam leaf powder pelleting @ 200g/kg, T6-1% KH2PO4+ Pongam Leaf Powder pelleting @200g/Kg, T7-100ppm Thiourea+ Pongam leaf powderpelleting @200g/kg and T8-1% CaCl2 + Pongam leafpowder pelleting @200g/kg.

During hardening, seeds were soaked inrespective chemical solutions and dried back tooriginal moisture content and then evaluated for theseed quality parameters viz., germination per cent,dry matter production and vigour index. From thehardened seeds, fifty per cent of them were againsubjected to pelleting with pongam leaf powder @200g kg-1 seed.

Germination test was conducted with 100x5seeds for each treatment by roll towel method at 25± 2ºc and 95 ± 2 % relative humidity. At the end offourteen days, the number of normal seedlings wascounted and germination per cent was calculatedas per ISTA, (1999) and expressed in whole number.Ten normal seedlings taken at random from eachtreatment replication-wise were dried in a hot airoven at 85ºC for 24h and cooled in a dessicator forrecording dry matter production in mg.seedlings-10.The vigour index was computed by adopting theprocedure of Abdul Baski and Anderson (1973) andexpressed as whole number.

Vigour index = Germination Percentage X TotalSeedling Length (cms)

Among the four varieties tested viz., ADT43, ADT 38, ADT 36 and ADT 39, ADT 43 wasfound to be more adoptive to aerobic condition.Hence, field experiment was conducted with ADT43 with the same treatments in RBD with threereplications and observations on plant height, leafarea and physiological parameters viz., leafphotosynthetic rate (Pn), transpiration rate (Tr),stomatal conductance(Cs), intercellular CO2concentration(Ci) and root dry weight and wholeplant dry weight were recorded. The data weresubjected to statistical analysis and discussed.

The height of the plant was measured fromthe ground level to the tip of the plant at peakvegetative stage and flowering phases and meanvalue was expressed in centimeter. Leaf area ofindividual plant was measured using portable leafarea meter AM 300. Gas exchange parameters viz.,leaf photosynthetic rate, transpiration, stomatalconductance and intercellular CO2 concentrationwere measured from two uppermost fully expandedleaves on intact plants in the field using LICOR-6400XT Portable Photosynthetic system (Lincoln, USA).All these estimations and measurements were madebetween 10.00–11.00 a.m. on four replicates undereach treatment randomly selected ten plants plot-1

were removed at harvest from the field, dried in ahot air oven at 85oC for 24 hours and cooled in adessicator, weighed and the root dry matter andwhole plant dry matter were recorded and expressedas g plant-1. Seeds from the ten marked plants ineach treatment were collected manually, cleaned,dried to constant moisture content, weighed and themean seed yield was recorded in g plant-1.

RESULTS AND DISCUSSIONFrom the results it was observed that among

the four varieties tested, ADT 43 recorded highestgermination percentage (81.60 & 93.30 %) bothunder normal condition and in seed treatment(Table 1). The seeds hardened with KCl (1%)followed by pelleting with pongam leaf powder @200 g kg-1 recorded higher germination, root length,shoot length, seedling dry matter and vigour indexover control (Fig1). Under normal condition, ADT39 recorded higher dry matter production whereasADT 43 recorded higher dry matter production inresponse to seed treatment. The dry matterproduction was higher when the seeds hardened withKCl followed by pelleting with pongam leaf powder.

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FIG. 1: Effect of seed hardening and pelleting on seedling growth and yield characters in four rice varieties.

Presowing hardening is one of the methods whichhelps in physiological manipulation of seeds that arefavorable for abiotic stress tolerance. Farooq et al.(2006a) introduced a technique called“osmohardening of rice” for rice seed invigourationthat successfully integrated hardening andosmoconditioning. Hydropriming, osmopriming,hardening and osmohardening have been optimizedfor vigour enhancement in rice (Farooq et al., 2005,2006a; Basra et al., 2006). Osmohardening withCaCl2 was found most effective by recording higheremergence index and emergence percentage(Muhammad Farooq et al., 2006). The vigour index

of seedlings was improved by hardening andpelleting treatment probably due to enhancement ingermination and seedling growth. Seeds hardenedwith KCl (1%) followed by pelleting with pongamleaf powder increased the plant height, leaf area,physiological parameters viz., leaf photosyntheticrate, transpiration, stomatal conductance,intercellular CO2 concentration and root dry weight(Table 2). It is possible that the bionutrients availablein the pelleted seeds might have improved seedlinggrowth resulting in higher plant height. Jegathambal(1996) observed increased plant height at all stagesof growth in sorghum due to seed hardening

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followed by pelleting with pongam leaf powder.Exogenous application of glycine betaine as a pre-sowing seed treatment increased shoot fresh biomassand leaf area per plant (Tahir Mahmood et al., 2009).Frommhold et al. (1987) reported increasedphotosynthetic rates and decreased CO2compensation point in tobacco seedlings treatedwith thiourea. The increased grain yield with CaCl2@ 2% followed by ZnSO4 @ 0.1% might beattributed to increased growth and yield parametersas well higher photosynthesis, stomatal diffusiveresistance and reduced transpiration rate (Pawar etal., 2003).

Turna Doegan and Ahment Zeybek (2009)recorded significant differences between the pelletedand non pelleted seeds in terms of the height of theplants (cm), number of branches per plant andnumber of capsules per plant in sesame. Vigneshwariet al. (2005) observed improvement in physiologicaland biochemical parameters of hardened andpelleted seeds over control. Umarani et al. (2003)reported that seed hardening with 1% prosopis leafextract for 1 hour followed by seeds pelleted withDAP @ 40g + ZnSO4 @ 100 mg + Fe SO4 @ 100mg + ammonium molybdate @ 250 mg using 10%maida as an adhesive improved seed yield and otherquality characters in green gram.

The seed yield per plant was maximum inseeds hardened with KCl (1%) followed by pelletingwith pongam leaf powder. The hardening andpelleting treatment might have improved the growthof the plant during early stages with increased vigourand associated stronger root system which in turnresulted in higher yield (Jegathambal, 1996).Muhammad Farooq (2009) reported thatosmohardening with KCl performed better and it wasfollowed by osmohardening with CaCl2 andascorbate priming in improving growth, yield andquality of transplanted rice.

Osmohardening with CaCl2 recorded the bestyield followed by hardening and osmohardeningwith KCl (Muhammad Farooq et al., 2006). In directseeded fine and medium grain rice varieties,osmohardening with CaCl2 and KCl recorded morekernel yield when compared to control (Farooq etal., 2011). Osmoregulation with KCl or CaCl2improved germination, kernel yield (due to moretillers, 1000 kernel weight) and grain quality (due toimproved kernel protein and kernel water absorptionratio (Farooq et al., 2006c).

Hence it may concluded that seed hardeningwith KCl (1%) followed by pelleting with pongamleaf powder @ 200g kg-1 is found to be the mosteffective treatment to grow rice under aerobiccondition.

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TABLE 2: Effect of seed hardening and pelleting on physiological parameters in rice.

Treatments

Plant height (cm)

Photosynthesis rate

(mg CO2 m-2 s-1)

Transpiration rate

(mg H2O m-2 s-1)

Intercellular CO2

concentration (µ mol mol-1)

Stomatal conductance (mol m-2 s-1)

Leaf area (cm2.pl-1)

Root Dry wt. (g / pl-1)

Total Dry matter

production (g / pl-1)

Single plant yield(g)

T0 146.1 24.31 7.414 310.3 0.431 1577.2 6.47 42.95 22.87 T1 152.4 26.88 7.598 318.4 0.477 1755.2 7.17 50.93 23.25 T2 150.1 28.16 8.116 323.6 0.537 1855.5 7.93 56.44 24.37 T3 150.2 27.38 7.657 321.4 0.514 1817.6 8.13 60.43 24.88 T4 151.2 26.32 7.632 320.3 0.514 1659.1 8.23 61.34 25.72 T5 154.5 28.31 8.218 339.1 0.585 1937.8 8.63 63.33 28.55 T6 153.2 26.84 7.884 328.5 0.533 1757.4 8.27 60.83 26.44 T7 154.0 26.43 7.156 314.8 0.567 1854.3 8.23 61.13 27.11 T8 153.4 28.26 8.156 334.8 0.573 1911.4 8.14 61.44 27.66 CD (0.05) 14.3 2.81 1.15 11.31 0.006 68.3 1.31 4.9 0.53

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