Effect of Water Stress on Yield of Rice Crop

International Journal of Ecology & Development Fall 2005, Vol. 3, No. F05; Int. J. Ecol. Dev. ISSN 0972-9984 ( Print ); ISSN 0973-7308 (Online) Copyright © 2005 IJED, ISDER

Effect of Water Stress on Yield of Rice Crop G. Venkatesan*, M.Tamil Selvam**, G. Swaminathan*** and S.Krishnamoorthi**** * Department of Civil Engineering, SHANMUGHA Arts, Science, Technology & Research Academy (SASTRA) University, Thanjavur, India

**Department of Civil Engineering, Government polytechnic, Tiruchirappalli- 620 015, India ***Department of Civil Engineering, National Institute of Technology, Tiruchirappalli- 620 015,India ****

Department of Civil Engineering, Meenakshi College of Engineering, Malliankaranai Village, Uthiramerur Taluk, Kanchipuram District, Tamil Nadu, India ABSTRACT Irrigation is the most important factor, which affects the productivity of the crop up to a great extent. The rainfall is uneven and erratic, often the water supply is inadequate for irrigation. So, problems of meeting crop water requirements arise. When water supply is less than the crop water requirements, the yield of crop gets affected. To manage irrigation with limited water supply, it is essential to yield response to limited water supply in various crops have to be conducted. A case study done by water stress was imposed two varieties namely ADT-36, a short-term variety and SONAM, a medium term variety were tried for the experimental study. Soil moisture depletion of 60% and 40% of field capacity were considered for experimentation. The study showed that the yield was affected due to water stressing. However yield reduction was less in 40% stress treatment compared to 60% stress treatment in various stages. Again, a scrutiny of yield obtained shows more yield reduction in stress treatment given in panicle initiation and flowering stages than in tillering stage when compared with no stress condition. Therefore, reproductive phase was more critical than the vegetative phase. It again shows that between the two varieties ADT-36 was better to water stress treatments. The study has shown that the yield reduction was less when 40% stress treatment was imposed in tillering stage only. This indicates that a still milder stress in tillering stage may fetch a comparable yield with the yield of no stress condition and at the same time will result in considerable water saving.

Key words: Rice, ADT-36, SONAM, yield, stress, moisture depletion, water stressing. INTRODUCTION Water is very vital for mankind and other living things including crop. Water and land are the basic inputs for agriculture and both are scarce in these days. Indian agriculture is monsoon dependent. If monsoon fails, Indian agriculture will fail. There fore, irrigation, which is the artificial application of water to soil for the purpose of crop production, becomes necessary in our agricultural practices. Rice occupies about 40% of the irrigated area in the Indian country. Its water requirements are many times more than most of other grain crops .Its therefore, a major consumer of the water resource and needs careful water management. In India one to three crops of rice could be taken annually. In southern parts of the India, there are four rice growing season i.e. June-September (Kuruvai), AugustDecember (Samb), October- January (Thaladi), February-May (Navarai). Several varieties of rice have been evolved to suit different seasons and these vary in maturing period from 100-160 days or more. Thus we have short-term varieties (90-110 days), medium term varieties (115-135 days) and long-term varieties (140-160 days) Experiments conducted in various locations in India (Bhatia and * Email of corresponding Author: [email protected]

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Dastane1971, Hukheri and Sharma, 1980) and consolidated reports under All India Co-coordinated project on water management (Yadav, 1972) showed that maintaining a shallow submergence of 5r2 cm during the entire growth period was beneficial to rice in terms of Yield. At the same time, scheduling intermittent submergence was found to be as good as continuous submergence in terms of grain yield (Gorantiwar et al. 1973; WTC 1986; CPRWM 1984; Tripathi et al, 1986). Scheduling irrigation a day after the disappearance of pounded water (Sandhu et al. 1980; CPRWM 1988), 2to3 days after disappearance of ponded water (Jha et al. 1981; WTC 1989), once in 4 days with 4 cm depth (singh et al. 1977) and once in 7 days with 5r2 cm depth

(CRRI 1983)

gave comparable yields with continuous submergence depending upon the season and location of the study. (Choudury ed al. 1991) observed that the grain yield did not vary between continuous submergence and irrigation once three days after disappearance of ponded water, besides a net saving of 24% of the water requirement in later practice. The grain yield of the rice decreased with increasing soil water deficit from continuous submergence to rain fed regimes irrespective of water table conditions (Mishra et.al. 1997) Rice is a major consumer of irrigation water. Through there are innovative methods such as sprinkler irrigation, drip irrigation available to increase the irrigation efficiency, they are not suitable for a crop like rice which demands standing water for its growth. Therefore as an alternative, the water stressing method was adopted and its effect on yield of rice was studied. A field experiment was conducted at the demonstration cum research farm of National Institute of Technology, Trichy, India during July 02 – Nov. 02 to study the effect of moisture stress on yield of rice under different stress treatments during various stages of the crop growth. Two varieties ADT – 36, a short-term crop and SONAM, a medium term crop were tried for the experimental study. Soil moisture depletion of 60% and 40% of field capacity were considered for experimentation. 12 plots of 3m x 3m were chosen for each variety. Irrigation was scheduled to maintain 5 cm depth of water in the plots except during the period in which the stress treatments were given. During the stressing period 5 cm irrigation was given only when the soil moisture reached the corresponding moisture treatment level. OBJECTIVE OF THE STUDY An Experimental study was conducted on rice crop with following objectives: 1. To determine the effect of water stress on yield of rice crops. 2. To decide the critical periods for rice crops for water stressing. 3. To schedule irrigation using soil moisture depletion.

MATERIALS AND METHODS Field experiments were conducted to study the effect of moisture stress on rice yield under two different stress conditions during various stages of the crop growth ADT-36, a short-term variety and SONAM, a medium term variety. The experiments were conducted at demonstration-cum-research farm, National Institute of Technology, during July 2002 – Nov 2002. Materials The demonstration-cum-Research farm, National Institute of Technology, is geographically situated at 10q 45’ north latitude and 78q 46’ East longitude with an altitude of 78 m above MSL in the Eastern side of the college campus .The experimental site has sandy loam texture. The soil samples were

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International Journal of Ecology & Development

collected from the main field and tested for its characteristics. The soil characteristics of the experimental site are given in Table 1. .Field capacity of the soil is the moisture content after drainage of gravitational water has become very slow and the moisture content has become relatively stable. It is also defined as the amount of water a well-drained soil holds after free water has drained off. It is thus, the maximum amount of water, a soil can hold against gravity. At field capacity, the large soil pores are filled with air, the micro pores are filled with water and any further drainage is slow. Field capacity was determined by ponding water on the soil surface in an area of 4 m2 and permitted to drain for 2 days with surface evaporation prevented. Soil samples were collected in the wetted zone and the moisture content was determined by gravimetric method. The field capacity of the soil was found to be 19.9 % the experimental plots were irrigated by Bore well water, which is available with in the farm. Water samples were collected from the bore well and tested. The characteristics of irrigation water quality are given in table 2.

VARIE RICE TIES USED IN THE EXPERIMENT: ADT – 36: ADT stands for Aduthurai. It is a rice variety released by Tamilnadu Rice research Institute, Aduthurai, India. It is a short-term variety with the duration ranges from 105-110 days. It has the parentage of Triveni/IR 20. It is being cultivated in Chengalput, North arcot, South arcot, Tiruchirappalli, Thanjavur, Pudukkottai and Madurai districts in Tamil Nadu, India. The average yield is about 4000 kg/ha. The grain type is medium and the grain L/B ratio is 3:1. The length, breadth, thickness of the grain is 7.8mm, 2.5 mm and 2.0 mm respectively. SONAM: It is a kind of hybrid variety. Hybrid varieties are normally high tillering, nitrogen responsive and high yielding varieties. The Indian council of Agricultural Research (ICAR), New Delhi initiated the hybrid rice research in India during the year 1989. Sonam is a fine grained rice variety developed by Ankur seeds limited, Nagpur. Plants are dwarf, strong with good tillering ability. This is a medium duration variety with duration around 125 days in south. The average yield is about 5000 Kg/ha. The lengths, breadth of the grain are 4.9mm, 1.5 mm respectively with L/B ratio of 3.27. METHODS The Nursery and main field were selected in the southern side of the research farm. An area of 12 m2 was selected for nursery with dimension 3m x 4m for each variety. Main field with 24 plots of 3m x 3m size was prepared. These plots were arranged in 4 rows with six plots on each row. Two rows totalling 12 plots were chosen for each variety. Cultural operations other than the treatments were done as per the recommendations of crop production manual, 1982, published by Directorate of Agriculture, Tamilnadu, India. Samples of seed with 100 numbers of grains were subjected to germination test. The sprout rate was found to be 95% and 96% in ADT-36 and Sonam respectively. The soil of the nursery bed was prepared loose without weeds, moist and fertile. This was done by plouging and puddling. After that the field was levelled. Rice seed treated with thiram were soaked in water for 20 hrs. Then the excess water was drained and the seeds were placed in a clean moist bag, tightly folded and kept in a dark room for 24 hrs. Sprouted seeds were taken out and uniformly broad


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casting on the nursery bed on 28.07.02 did sowing. The seed rate of 24kg/acre and 12kg/acre was followed in ADT- 36 and Sonam respectively. The quantity of water was increased from 2 cm to 3 cm depending upon the height of seedlings. To protect seedlings from thrips 1Kg of BHC Dust / Acre was applied. Urea was applied at the rate of 500 g/ 40m2 of nursery on the 18th day after sowing. The seedlings were pulled out for transplanting on 25th day and 27th day from the date of sowing in the case of Sonam and ADT-36 respectively. Main field was prepared in an area of 216 m2. The field was prepared with 24 plots each of 3m x 3m size. Of these, 12 plots arranged in 2 rows were chosen for transplanting each variety. The fields were first flooded. A few days after flooding, the fields were ploughed. Ploughing is the initial breaking and turning over of the soil. Flooding makes ploughing easier. Ploughing was done by hand (with a hoe) 4 times. After ploughing, the soil was puddled. During puddling, the big soil clods were broken. Puddling reduces the permeability of the soil and therefore also reduces the percolation losses. After puddling, the soil was levelled; that is the soil was made flat. To facilitate the levelling, the soil was flooded with a shallow water layer (2 cm) and levelling was done with a shovel and levelling boards .The layout was done with the provisions of field ditch between two bunds. 2 cartloads of farmyard manure were applied to main field. Recommended dosage of DAP, Murate of potash and zinc sulphate were applied on the day of last plough. Azozpyrillam and phospho bacteria were also applied. The crop was top dressed with urea on 25th to 45th day after transplantation. Twenty five days old seedling of Sonam was transplanted at two seedlings per hill with a spacing of 20cm x 15 cm on 21.08.02. Similarly, twenty seven days old seedlings of ADT-36 were transplanted at three seedlings per hill on 23.08.02 with same spacing. The hill density was 30 hills/m2. During transplanting a shallow depth of water (2.5 cm) was maintained. Next day the field was allowed to dry. Hand weeding alone was resorted to on 15th and 35th day after transplantation. Monocrotophos - 36 EC, Indofil M45, and Carbofuron were used to control pest and disease. It is well aware that rice responds to water management practices. The common practice of flooding in rice cultivation is widely practiced although attempts were made earlier to economize water usage and maximize yields by alternate wetting and drying and such other management practices. Moisture stress at any stage may reduce yield of rice. However, it showed differential tolerance both to intensity and duration of stress applied at different growth stages and favour growth and yields. The earlier experimental results showed that scheduling intermittent submergence was as good as continuous submergence interims of grain yield. With this background, in this experimental study irrigation treatments were imposed on ADT-36 and Sonam varieties based on soil moisture content. The field capacity of the soil is 19.9%. Soil samples were collected from the plots S1 (control), S2, S8, A2, A8 daily at 7.00 a.m. and were tested to find out the daily moisture content. In plots S3 to S5, S9 to S11, A3 to A5, A9 to A11 the samples were collected to find out the moisture content during the stage in which the crops were stressed. Water depth of 5 cm was given throughout from transplantation to 1 week before harvesting in the plots meant for control. In other plots meant for 60% stress and 40% stress treatment, irrigation was given to a depth of 5 cm when the soil moisture depleted to a level of 60% of field capacity and 40% of field capacity respectively, during the corresponding growth stages. During rest of the periods 5 cm depth of water was maintained as usual. Experimental technique Variety: - ADT-36 Expt No: 1 Control (No Stress) Daily irrigation to restore 5 cm depth in the plots A1, A6, A7 and A12. Expt No: 2 60 % Water Stress

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Irrigation to 5 cm when the soil moisture depleted to a level of 60 % of the field capacity during 1) Tillering to harvest period (Plot A2) 2) Tillering stage only (Plot A3) 3) Panicle initiation stage only (Plot A4) 4) Flowering and Milky stage only (Plot A5) Expt No: 3 40 % Water Stress Irrigation to 5 cm when the soil moisture depleted to a level of 40 % of the field capacity during 1) Tillering to harvest period (Plot A8) 2) Tillering stage only (Plot A9) 3) Panicle initiation stage only (Plot A10) 4) Flowering and Milky stage only (Plot A11) Variety: - Sonam Expt No: 1 Control (No Stress) Daily irrigation to restore 5 cm depth in the plots S1, S6, S7 and S12. Expt No: 2

60 % Water Stress

Irrigation to 5 cm when the soil moisture depleted to a level of 60 % of the field capacity during 1) Tillering to harvest period (Plot S2) 2) Tillering stage only (Plot S3) 3) Panicle initiation stage only (Plot S4) 4) Flowering and Milky stage only (Plot S5) Expt No: 3 40 % Water Stress Irrigation to 5 cm when the soil moisture depleted to a level of 40 % of the field capacity during 1) Tillering to harvest period (Plot S8) 2) Tillering stage only (Plot S9) 3) Panicle initiation stage only (Plot S10) 4) Flowering and Milky stage only (Plot S11) The layout plants shown in Fig.1.

Irrigation Schedule for ADT-36 and Sonam (based on soil moisture depletion) In the plots meant for control (No stress), irrigation was done daily to maintain a depth of 5 cm from transplantation to 1 week before Harvesting (A1, A6, A7, and A12 plots in ADT-36 and S1, S6, S7 and S12 plots in SONAM), In other plots irrigation was done daily as above except during the corresponding periods in which the plots were subjected to water stressing. The schedule (stress period only) in given Table.3.to table 6. Rest of the period daily irrigation was given for a depth of 5 cm in the corresponding plots.


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Harvest Border plants on all sides were harvested first and the plants from the net plots (1 m2) were then harvested and threshed. The grain yield and straw weight were recorded. ADT-36 was harvested on 11.11.02 and Sonam was harvested on 22.11.02.

OBSERVATION RECORDED: Crop growth characters and yield components The following growth characters were recorded on 45th day after transplanting and yield componends at Harvest. It includes shoot length, plant height, leaf length, leaf width, number of tillers per hill, Number of hill / m2 etc. and the same is table 7 to 10.

RESULTS: The yield parameters are the corresponding water supplied at 60 % water stressing and 40% water stressing in ADT-36 and Sonam were recorded and are given in table 11 to 14.

DISCUSSION Rice is the major crop in the irrigated area (70 percent) of Tamil Nadu, India consuming 86 Percent of the available irrigation water. Water when most judiciously used may help diversion to other crops or to increase the irrigable area under rice. In command areas, farmers with widening the frequency of successive irrigations by force of circumstances of inadequate storage of water in the reservoir during the crop season are resorting to intermittent water supply. This practice often results in reduction in rice grain yield resulting in uneconomic returns. Recently ‘Water saving techniques’ have been introduced to establish the relationship between water input and rice yield to find out how far water input can be reduced without compromising yield and to optimise scarce water in rice production. With this background, experiments were conducted at demonstration-cum Research form of National institute of Technology, Tiruchirappalli to economise irrigation water use through the adoption of water stressing at various stages. The results presented are discussed here under. Water stress in various stages of crop growth reduced grain yield and straw yield and has its impact on growth of rice crop. The panicle length, number of grains per panicle, test weight of 100 grains was lower at stressed conditions. The number of chaffy grains per panicle was also found to be more in the crops under stressed condition especially in tillering to Harvest and flowering stage treatment. However the yield components were not much affected in the stress treatment given in tillering stage only. It seems that plant tolerated to stress conditions when the stress was imposed in the vegetative stage than other stages. Water is a vital and scarce input and any effort in increasing its use efficiency will be rewarding as, over all production could be stepped up to that extent. In the water supplied in the experiment, the contribution from rainfall was very less as there was not much rain in that particular season. Hence the irrigation schedule was not much affected during these stress treatments. Water supply to stress treatment in ADT-36 showed that 40.8% 14.3% 16.5% 6.2% and 39.1%, 12.9 %, 16.5%, 6.2% of water was saved in tillering to Harvest, tillering panicle initiation and flowering & milky stage with 60% and 40% stress treatments respectively. Similarly water supply to stress treatment in Sonam showed

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that 42.7%, 19.7%, 14.6%, 5.7% and 39.4%, 18.1%, 12.9%, 5.7% of water was saved in tillering to Harvest, tillering panicle initiation and flowering & milky stage with 60% and 40% stress treatments respectively. The quality of bore well water used in the experiment was found fit for the irrigation of rice crop. After the cultivation of rice crop, the soil characteristics were studied and it was found that decrease in N and P values may be attributed to nutrient loss in plant use up. However K was not effective in crop growth and the added fertilizer has increased the soil K value. How ever the soil samples collected from stress treatment plot (tillering to harvest) showed improvement in N, K values and reduction in P value. CONCLUSION

Both short term and medium duration varieties that were has responded in same way to water stressing in respect of grain yield, That is, yield reduction was more in 60% water stressing than in 40% water stressing. It seems severity in yield reduction depends on percentage of water stressing. Again among various growth stages rice crop, panicle initiation and flowering stages were more susceptible to water stressing and its resulting percentage reduction in yield was more comparing other stages. Therefore, it is advised not to venture water stressing during panicle initiation and flowering stages, which may drastically reduce the percentage of yield with little percentage of saving in water. However considerable percentage of water saving may be achieved by water stressing during tillering stage, which will reduce only meager percentage of yield. Scope for further study The degree of tolerance to water stressing may be studied right from nursery stage (two leaf stage). The yields from shallow submergence say 2.5 cm and at saturation at all stages may also be studied. A still lesser moisture stress may be tried to obtain a comparable yield.

Reference: 1. Bhatia P C and Dastane N G, 1971, Effect of intermittent drying at different growth stages on new rice varieties. Agron. J. 16, 344-347. 2. CRI-Central Rice Research Institute, ICAR, Cuttack (Orissa), India. 3. Crop production manual, Directorate of Agriculture, Tamil Nadu, Crop production manual, Directorate of Agriculture, Tamil Nadu, India, 1982. 4. Crop water requirement and Irrigation Food and Agricultural organization (FAO) of United Nation, 1997. 5. CPRWM 1984.Annual Progress Report, Coordinated Project for Research on Water management (ICAR), Rajendranagar, Hyderabad, India. 6. Development of drought response plan-water availability, National Institute of Hydrology, Roorke, 1992. 7. Gandhi.R. 1971, Hand book on Irrigation water management, Department of Agriculture, New Delhi. 8. Gorantiwar S M, Jaggi I K and Khanna S S 1973 Nutrient uptake by rice under different soil moisture regimes. J. Indian Soc. Soil Sci. 21, 133-136. 9. Hukkeri SB, Sharma AK, 1980, Water use efficiency of transplanted and direct sowed rice under different water management practices, Indian journal of Agricultural science 50:240-243.


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10. Janardhan pillai. S, Geethalakshmi.V, 1997, Agronomical management to improve thaladi paddy, pp 331-335. 11. Jha KP, Dinesh Chandra, Challaiah, 1981, Irrigation requirement of high yielding rice varieties grown on soils having shallow water table. Indian J. Agric. Sci. 51:732–737. 12. Krishna Moorthi S., 1990, System analysis for irrigation water management on Farms, National workshop on WR project management, Madras. pp 156-161. 13. Maskina, M.S., Yadvinder-Singh and Bijay-Singh (1987). Wheat straw management for rice on a coarse-textured soil. Int. Rice Res. News. 12(2): 40. 14. Maskina, M.S., Yadvinder-Singh and Bijay-Singh (1987). Response of new rice varieties to N. Int. Rice Res 15. Maskina M.S., Bijay-Singh and Yadvinder-Singh (1987). Effect of transplanting date and N application on yield. Int. Rice Res. Newsl. 12(4) : 52-53. 16. H. S. Mishra · T. R. Rathore · R. C. Pant, 1997, Root growth, water potential, and yield of irrigated rice, Irrig Sci, 17: 69–75. 17. Muterja, K. N., 1990, implied hydrology, Tata Mc-Graw Hill publishing company Ltd, New Delhi. 18. Narayanasamy M.R. and Subramaniam.P.S, 1999, Influence of time of nursery seed on the productivity of low land paddy” vistas of paddy research, TRRI, Aduthurai, pp 299-304. 19. Narayanasamy M. R and Subramaniam P.S., 1999, Influence of heat units and solar energy on the productivity of low land rice vistas of rice research, TRRI, Aduthurai, pp 299-304. 20. Panchanathan R.M, 1997, Irrigation system management under scarcity condition, Irrigation Management of paddy, TNAU, Coimbatore. 21. Ponnusamy, P. Santhi and M. Subramanian, 1999, Effect of planning methods on the growth and yield of rice’ vistas of rice research, TRRI, Aduthurai PP 237-240. 22. Raman H., John S. M, Ranga Charya 1990, N.C.V, Expert System for Drought Management’ National work shop on WR project management, Madras. PP 121-130. 23. Sandhu BS, Khera KL, Prihar SA, Singh B, 1980, Irrigation needs and yield of rice on a sandy loam soil as affected by continuous and intermittent submergence. Indian J Agric Sci 50:492– 496. 24. Subramaninan.S, Kulandaivelu, 1987, Crop water requirement and scheduling irrigation for crops in Tamil Nadu state, Publised by I.M.T.I. 25. Tripathi RP, Kushawa HS, Mishra RK. 1986. Irrigation requirements of rice under shallow water table conditions. Agric. Water Manage. 12:127–136. 26. Vera S.K, Mani.S.C and Paney.M.P, 1997, Hybrid rice: past, present and future, Tamil Nadu rice research Institute, Aduthruai, P.P62-72. 27. WTC-Water Technology Centre, Indian Agricultural Research Institute, New Delhi. 28. Wilson.E.M, Engineering Hydrology, 1990, Mac Millan press Ltd, London. 29. Yadav JSP, 1972, Water management and irrigation scheduling in relation to rice production, Orya 9:77-96

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Sl.no

1. 2. 3. 4. 5. 6.

Table 1. Soil characteristics of the Experiment site Test Result Before After experiment Experiment Dry density (gm/cc) 1.87 1.84 Specific gravity 2.52 2.47 Bulk density (gm/cc) 2.03 2.03 N, P, K (kg/Acre) 75.6,67.5,140 68.6,20,170 PH 8 8 EC (mmhos/cm) 0.7 0.56

Table 2 Characteristics of irrigation water Sl .no 1. 2. 3. 4. 5. 6. 7. 8.

Component PH EC Total solids Dissolved solids Suspended solids Hardness Chlorides Sulphates

Values 7.19 0.63 mmhos 400 mg/l 200 mg/l 200 mg/l 255 mg/l 74.93 mg/l 305.4mg/l

Table3. Period of water stress in the corresponding plots: ADT-36 Sl. No

Treatmeant stage

Period

Days

Plots

1 2. 3. 4.

Tillering to Harvest Tillering only Panicle initiation only Flowering and milky stage only Control (No Stress)

31.08.02-11.11.02 31.08.02-17.09.02 18.09.02-08.10.02 09.10.02-19.10.02

72 18 21 11

60% stress A2 A3 A4 A5

40% stress A8 A9 A10 A11

23.08.02-11.11.02

80

A1, A6

A7, A12

5.

Table.4.Observed irrigation dates in ADT-36. Sl. No

ADT-36

Irrigation Dates

1.

Tillering To harvest

At 60% moisture depletion 31.08.02, 09.09.02, 19.9.02,28.09.02, 6.10.02,15.10.02, 26.10.02,03.11.02

2.

Tillering only

31.08.02,09.09.02

2

3.

Panicale initiation only Flowering and milky stage only

18.09.02,27.09.02, 6.10.02

3

18/9,25/9,3/10

3

09.10.02,18.10.02

2

09.10.02,16.10.02

2

4.

Number of During that stage only 8

Irrigation Dates At 60% moisture depletion 31.08.02,07.09.02 14.09.02,22.09.02, 30.09.02,08.10.02 16.10.02,24.10.02, 3.11.02 31.08.02,07.09.02, 14.09.02


3


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Table.5.Period of water stress corresponding plots - Sonam Sl No

Treatmeant stage

Period

Days

Plots

1 2. 3. 4.

Tillering to Harvest Tillering only Panicale initiation only Flowering and milky stage only Control (No Stress)

29.08.02-22.11.02 29.08.02-24.09.02 25.09.02-18.10.02 19.10.02-30.10.02

85 27 24 12

60% stress S2 S3 S4 S5

40% stress S8 S9 S10 S11

21.08.02-22.11.02

93

S1, S6

S7, S12

5.

Table.6. Observed irrigation dates in Sonam Sl.N o

Sonam

Irrigation Dates At 60% moisture depletion 29.08.02,07.09.02, 17.09.02,26.09.02, 04.10.02,13.10.02, 22.10.02,02.11.02, 11.11.02,14.11.02

Number of During that stage only

1.

Tillering To harvest

2.

Tillering only

29.08.02,07.09.02 17.09.02

3

3.

Panicle initiation only Flowering and milky stage

25.09.02,04.10.02, 13.10.02 19.10.02,27.10.02

3

4.

10

2

Irrigation Dates At 60% moisture depletion 29.08.02,05.09.02 12.09.02,19.09.02, 25.09.02,02.10.02, 11.10.02,18.10.02 25.10.02,04.11.02, 11.11.02,14.11.02 29.08.02,05.09.02, 12.09.02,19.09.02 25.09.02,02.10.02 11.10.02,18.10.02 19.10.02, 25.10.02

Table.7.ADT-36 (45th day after transplanting) 60% stress 06.10.02


4 4 2

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Table.8.ADT-36 (45th day after transplanting) 40% stress 06.10.02

Table.9. Sonam

(45th day after transplanting) 60% stress 04.10.2002

Table.10.Sonam (45th day after transplanting) 40% stress 04.10.02


Table11.ADT-36 yield and Water supply details-plot wise At 60% moisture depletion

Table 12.ADT-36 yield and Water supply details – plot wise At 40% moisture depletion:

Table 13. Sonam yield and Water supply details – plot wise At 60% moisture depletion

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Table 14. Sonam yield and Water supply details – plot wise At 40% moisture depletion