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effect of different weather elements on growth and development of rice crop

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The document discusses the impact of various weather elements on the growth and development of rice crops. It highlights temperature, rainfall, and their effects on stages such as germination, vegetative growth, reproductive, and ripening, emphasizing optimal temperature ranges for germination and growth. Additionally, it addresses the significance of rainfall distribution on crop yield, indicating that water availability and rainfall characteristics are crucial for maximizing rice production.

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PROFESSOR JAYASHANKAR TELANGANA STATE AGRICULTURAL UNIVERSITY SUBMITTED BY: P.NANDINI, RAM/2018-09 SUBMITTED TO: Dr.G.SREENIVAS, PRINCIPAL SCIENTIST AND HEAD, ACRC,ARI,R. Nagar
EFFECT OF DIFFERENT WEATHER ELEMENTS ON GROWTH AND DEVELOPMENT OF RICE CROP
IMPORTANCE OF RICE  C3plant  90 %of the rice production- tropical/sub-tropical Asia -60 % of the world population lives.  Slogan- “RICE IS LIFE” -International Year of Rice 2004 -rice as primary source of food.  food security, poverty alleviation and improved livelihood.  staple food of over half of the world population .  Climate- the distribution of crops over different regions of the world.  weather - the potential production of the concerned crop.
1.TEMPERATURE 2.RAINFALL 3.SOLAR RADIATION 4.RELATIVE HUMIDITY 5.WIND Different weather elements are:
Vegetative Stage • Germination • Seedling Growth • Leaf Emergence • Plant height • Tillering Reproductive Stage • Panicle Initiation • Booting • Emergence of flag leaf • Heading • Flowering/Anthesis Ripening Stage • Maturity • Grain Filling • Grain Quality • Grain Weight GROWTH and DEVELOPMENT of RICE WEATHER ELEMENTS TEMPERATURE RAINFALL SOLAR RADIATION RELATIVE HUMIDITY WIND
GROWTH STAGES OF RICE GERMINATION TILLERING PANICLE INITIATION HARVEST SEEDLING MAXIMUM TILLERING FLOWERING VEGETATIVE STAGE REPRODUCTIVE STAGE RIPENING STAGE
Effect of Temperature: GERMINATION: Optimum temperature for germination is 20-35oC Low temperature depresses the rate of germination and prolongs it beyond the desirable span of 6 days. High temperature of 35 ºC or more halted the germination because of high respiration rate . VEGETATIVE STAGE
Genotypes of Rice Temperature (oC) 12oC 16o C 20oC 25oC 27oC 30oC 33oC 36oC 40oC Sadri 0 80 92 94 95 98 93 65 0 Ahlami Tarom 0 93 97 96 100 96 92 72 0 Neda 0 92 97 94 100 98 96 70 0 Fajr 0 88 97 100 97 100 95 72 0 IR 42 0 65 91 86 97 98 94 62 0 Nearmat 0 80 95 96 93 99 95 68 0 IR 58 0 87 99 98 98 94 94 66 0 IR 8 0 66 93 92 99 96 93 64 0 Rashti 0 85 90 94 99 96 96 68 0 Salari 0 84 90 87 97 96 93 64 0 Table No.1: Effect of temperature on Germination percentages. Farhadi et al., 2012, Iran.
SEEDLING GROWTH: Seedling growth rate increases linearly between 22-31oC ,suggesting that chemical reactions dominate growth and above 40oC the plant may die. SHOOT AND ROOT ELONGATION: Critical minimum temperature for shoot and root elongation i.e.,7-16 oC and 12-16oC respectively. Elongation is a combination of two components : cell division and cell enlargement and for which extreme temperatures are 15oC and 40oC. LEAF EMERGENCE: Before panicle initiation, leaf emerges about every 4-5 days, afterwards about 7-8 days. Temperature affects the rate of leaf emergence. Eg: When the rice plant is grown at 20oC, leaves emerge every 5 days. When it is grown at 25oC, they emerge every 4 days before panicle initiation. Bardhan and Biswas (1983)
Mean temperature (oC) Leaves developed (no./main culm) Mean leafing rate (days/leaf)1st week 2nd week 3rd week 4th week 22 1.1 2.4 4.1 5.2 5.4 25 1.7 2.9 5.0 6.5 4.3 28 2.0 3.3 5.5 7.0 4.0 31 2.0 3.8 6.2 8.0 3.5 Table No.2: Leafing rate of IR-8 at different temperatures. Shouichi Yoshida, 1973, New Zealand.
Table No.3: Mean dry weight and mean relative growth rate of four varieties at different temperatures. Mean temperature (oC) Dry Weight (g/plant) Relative growth rate (g.g-1.wk-1) 3rd week 4th week 0 to 3 weeks 3 to 4 weeks 22 0.09 0.29 0.45 1.15 25 0.23 0.74 0.75 1.18 28 0.26 0.89 0.78 1.25 31 0.30 1.08 0.83 1.28 Mean 0.22 0.75 0.70 1.21 Shouichi Yoshida, 1973, New Zealand.· Initial weight was 0.024 g.
PLANT HEIGHT:  The plant height increased with the rise of temperature within the range of 30-35oC.  The plant elongates vigorously until 30 days after transplanting , then slowly ceases to elongate at the heading time. TILLERING:  Optimum temperature for tillering is 25-31 ºC.  Tillering rate is inhibited by low temperature, but the period of tillering is prolonged.
Planting Date of Daily mean temperature from T-MT (OC) Duration in days T-MT Duration in weeks T-MT Degree days T-MT T MT D1 13/07 15/08 26.7 34 5 567 D2 27/07 30/08 26.3 35 5 569 D3 13/08 13/09 26.2 32 5 517 D4 11/01 06/03 22.9 55 8 707 D5 25/01 13/03 24.2 48 7 683 D6 04/02 21/03 25.8 46 7 725 D7 10/07 14/08 26.5 36 5 593 D8 25/07 28/08 27.1 35 5 599 D9 13/08 17/09 26.7 36 5 602 Mean 618+54 Table No.-4: Effect of temperature on duration of tillering and accumulated degree days in Kharif & Rabi. T-Transplanting: MT-Maximum tillering stage Lalitha , Raji Reddy, 1994-95, ARI, Rajendra Nagar
Table No.5: Tiller number, dry weight, and relative growth rate of IR 8 at different temperatures during the period from 3 to 5 weeks after sowing. Mean Temperature (oC) Tiller no. Dry wt. (g) Mean relative growth rate (g.g-1.wk-1) 22 7.0 3.73 1.40 25 8.4 5.21 1.56 28 9.4 5.91 1.62 31 9.2 5.87 1.62 Shouichi Yoshida, 1973, New Zealand.Initial tiller number: 2.6, Initial dry weight: 0.24 g.
Table No.6: Growth rate of IR 8 at different temperatures upto 5 weeks after sowing. Mean temperature (Oc) Growth rate Ratio of growth rate 0 to 1 wk (mg.plant-1. wk-1) 1 to 2 wk (g.g-1.wk-1) 2 to 3 wk (g.g-1.wk-1) 3 to 5 wk (g.g-1.wk-1) 0 to 1wk 1 to 2wk 2 to 3wk 3 to 5wk 22 8.1 1.16 1.16 1.40 1.0 1.0 1.0 1.0 25 10.7 1.53 1.40 1.50 1.3 1.3 1.2 1.1 28 13.7 1.51 1.35 1.62 1.7 1.3 1.2 1.2 31 15.7 1.52 1.39 1.62 1.9 1.3 1.2 1.2 Shouichi Yoshida, 1973, New Zealand.
REPRODUCTIVE STAGE PANICLE INITIATION: After active tillering stage ,high temperatures decreases the number of panicles , panicle weight especially at maturity. BOOTING AND HEADING:  When the rice plant is subjected to low temperatures for 3days , it is more sensitive at the booting stage than heading, as indicated by the higher percentage of spikelet sterility.
SPIKELET STERILITY LOW TEMPERATURE HIGH TEMPERATURE The critical temperature for inducing spikelet sterility varied from 10 to 15 ºc. Cool weather causes panicle sterility by interfering with pollen grain formation.  Observed that the temperature and sterility had a negative correlation which indicated lower temperature induced high sterility. Stated that the reduced yield was a result of poor pollen shedding as well as inadequate pollen growth in temperature above about 34ºC. High temperature desiccated pollens . The high sterility may be attributable to failure of fertilization caused by the imperfect splitting of anther or wilting of stigma induced by high temperature and low humidity.
Fig-1: Effect of Temperature on yields of Rice World journal of Agricultural Research,2018,AP
RIPENING STAGE GRAIN FILLING,GRAIN QUALITY,GRAIN YIELD: Optimum temperature for ripening is 20-25 ºC. Low temperature reduced the grain dry matter increasing rate, extends the grain filling, delays grain maturation although moderate cool temperatures sometimes benefits grain yield .  High temperature decreased the grain yield significantly due to the reduction of percentage of ripened grains. FLOWERING: The optimum was 25-30oC. Yoshida(1981) observed that a 13 day delay in flowering for each degree drop in temperature between 24oC and 21oC inIR 26 rice cultivars. Higher temperature(both maximum and minimum) and lower diurnal variation in temperature are more conducive for early flowering in rice varieties.
Growth characteristics Mean temperatures (oC) 22 25 28 31 Days to flowering 140 127 118 131 Leaves developed (no./main culm) 19.5 20.2 20.5 21.7 Culm length 52.3 58.1 57.8 49.0 Flag leaf length (cm) 37.7 39.7 57.0 53.9 Flag leaf width (cm) 1.6 1.7 1.6 1.3 Dry weight of straw (g) 4.90 4.37 4.23 3.77 Dry weight of panicle (g) 1.98 1.72 1.66 0.76 Spikelets (no./ panicle) 272 227 207 157 Relative spikelet number 100 83 76 58 Table No.7: Growth characteristics and number of spikelets of IR 8 grown at different temperatures. Shouichi Yoshida, 1973, New Zealand.
CROP STAGE AMBIENT TEMPERATURE ELEVATED TEMPERATURE(2oC) ELEVATED TEMPERATURE(4oC) TOTAL DAYS DAYS TAKEN FOR PHENOLOGICAL STAGE TOTAL DAYS DAYS TAKEN FOR PHENOLOGICAL STAGE TOTAL DAYS DAYS TAKEN FOR PHENOLOGICAL STAGE Sowing Transplanting 20 20 20 Active Tillering 41 21 40 20 39 19 Panicle Initiation 53 12 51 11 50 11 Flowering 70 17 67 16 65 15 Maturity 108(A) 38 102(B) 35 96(C) 31 D(A-B)=6days, E(A-C)=12days Table No. 8: Effect of elevated temperature (2oC and 4oC) over ambient on duration of phenological stages of rice during Kharif. Arthi Rani and Maragatham, 2012, ACRC,TNAU
Growth stage Ambient Temperature Elevated Temperature (2oC) Elevated Temperature (4oC) Active Tillering 347.2 367.4 383.6 Panicle Initiation 209.8 214.9 236.0 Flowering 333.5 353.7 368.6 Maturity 633.0 646.8 653.0 AGDD (Transplanting to Harvest) 1523 1583 1641 Table No.9: Effect of elevated temperature (2oC and 4oC) over ambient on Accumulated Growing Degree Days (AGDD) during Kharif. Arthi Rani and Maragatham, 2012, ACRC,TNAU
Fig-2: Effect of elevated temperature over ambient with AGDD on yield during Kharif 2012. Arthi Rani and Maragatham, 2012, ACRC,TNAU
Effect of Rainfall:  Rainfall amount and distribution is the most critical weather component in rainfed rice ecologies (Upland, lowland and flood prone).  Its effect on irrigated ecology is indirect through availability of water in irrigation sources (tank, canal, well etc.,)  Daily rainfall is more critical than monthly or annual rainfall. A rainfall of 100 mm/month distributed evenly during the growing period was preferable than 200 mm/month, which fell in two or three days.  High rainfall during the active growth period resulted in taller plants and they lodge and decay in standing water.  TILLERING: In rainy season , is continued up to 42-45 days, whereas it is up to 50-55 days in dry season.  Total rainfall during nursery stage was negatively correlated with grain yield in non-significant manner but with straw yield it was significant and positively correlated. VEGETATIVE PHASE
Water deficit during the vegetative stage reduces the PLANT HEIGHT, TILLER NUMBER AND LEAF AREA but the crop can recover without much loss in yield if water is available before flowering.  Low yield was obtained due to continuous rain coupled with strong wind at flowering in wet season.  Due to heavy rainfall, panicles have large number of blank florets .  Moisture stress after 10 days of 50 % flowering significantly reduced single PANICLE WEIGHT, TEST WEIGHT, FERTILE SPIKELETS PER PANICLE, TOTAL SPIKELETS PER PANICLE AND SPIKELET DENSITY and significantly increased sterile spikelets per panicle.  QUALITY: muddy or turbid water inflicts a greater damage to plants than clear water because sediments in turbid water block the pores in the plant body and hamper the respiration and photosynthesis process.
RIPENING STAGE  Negative correlation between yield and number of rainy day during maturity phase.  Wet spells are detrimental to rice crop from flowering to maturity.  Deficit soil moisture during grain filling stage drastically reduces the grain yield even if there was normal rainfall during preceding phases. Yield variations are largely due to rainfall received during the grain filling stage of the crop. The beneficial influence persisted even when this factor was taken jointly with other climatic elements namely mean temperature and sunshine.
Fig-3: Sensitivity of rice yields to rainfall receipt Indian Agricultural Research Institute , Kharif 2012,New Delhi
S.No. Year Rainfall(mm) No. of rainy days Duration (days) Grain Yield (Kg ha-1) 1 1971 1573.1 63 103 753 2 1972 1344.4 34 79 463 3 1973 1320.1 61 104 417 4 1974 835.4 37 54 343 5 1975 1349.3 57 86 799 6 1976 978.0 50 73 513 7 1977 1729.2 53 84 1000 8 1978 1250.1 60 105 738 9 1979 467.2 26 56 13 10 1980 1551.0 56 95 526 11 1981 669.8 39 102 354 12 1982 1273.9 50 68 515 13 1983 1271.1 52 108 700 14 1984 1443.2 48 100 360 Table No.10: Rainfall features during monsoon months and yield of rainfed rice during (1971-1996).
S.No. Year Rainfall(mm) No. of rainy days Duration (days) Grain Yield (Kg ha-1) 15 1985 1471.4 56 80 801 16 1986 1097.1 65 89 234 17 1987 1123.4 45 77 629 18 1988 1011.8 50 98 663 19 1989 685.0 46 102 490 20 1990 1708.9 66 107 868 21 1991 1334.6 48 94 570 22 1992 1050.2 47 86 693 23 1993 1428.9 60 108 716 24 1994 2052.0 60 98 799 25 1995 1170.8 44 71 778 26 1996 658.7 44 68 593 (contd…………) Gupta et al., 2000, Jabalpur.
Effect of Solar radiation: VEGETATIVE STAGE  Rice yield during summer season becomes almost double of that of monsoon season in eastern and southern India whereas it increases marginally in Punjab.  Sunshine in a week prior to transplanting and the two weeks period coinciding with the grand period of elongation was conducive for better yield .  LAI reduced to a greater extent in plants shaded from planting to panicle initiation.  Shading(45-50 % reduction in sunlight) delayed tillering and decreased tillering rate.  Irrespective of varieties, shading increased the plant height, LAI and total chlorophyll content and significantly reduced the tiller number and total dry matter production  In long duration varieties, low light stress synchronizes with the vegetative lag phase results in considerable tiller mortality and fewer panicles m-2 .
 Solar radiation and Temperature during reproductive stage (before flowering) had the greatest influence on rice yield because they determine the number of spikelets m-2.  Higher accumulated solar radiation from transplanting to flowering resulted in more panicles m-2.  Leaves grown in low irradiance are thinner than the leaves of plants grown in higher irradiance.  The most critical sunlight requiring period was around the heading stage. During this period, a mean yield reduction of 6.5% was observed for every 1 % reduction in solar radiation.  Low light stress reduced grain number panicle-1 in short duration varieties, increased spikelet sterility in medium duration varieties and decreased panicle number in long duration varieties .
RIPENING STAGE  The yield attributes and grain yield recorded a positive correlation with solar energy during ripening stage.  Low light causes spikelet sterility, dry matter is reduced , weak and unproductive tillers, proline content decreases in the panicle .  Proline deficiency in the spikelet's may also be a factor in high sterility .  Dry matter accumulation during post flowering was more in dry than in wet season during ripening stage, which was due to higher solar radiation and demand of developing sink .  Cumulative solar radiation of 14,000 g cal cm-2 and 200 hours of sun shine during 30 days preceding to harvesting is optimum for obtaining maximum grain yield.
Fig-4: Peak stages of solar radiation requirement in Rice International Journal of Applied Research, 2015.
Crop growth phase Normal 2000 2001 2010 2011 Vegetative stage 609 529(-13%) 526(-13%) 498(-18%) 508(-16%) Reproductive stage 401 462(-15%) 454(13%) 304(-24%) 284(-29%) Transplanting to Physiological Maturity 1010 991(-1.9%) 980(-2.9%) 802(-20.6%) 792(-21.6%) Table No.-11: Crop stage wise sunshine hours during low rice yield(<4000kg ha-1) years. Sandhu et al., 2013, Ludhiana.
Crop growth phase Normal 2004 2005 2007 2009 Vegetative stage 609 608(-0.1%) 612(0.4%) 568(-6%) 669(9%) Reproductive stage 401 419(4%) 415(3%) 340(-15%) 391(-0.02%) Transplanting to Physiological Maturity 1010 1027(1.7%) 1027(1.7%) 908(-10.1%) 1060(4.9%) Table No.-12: Crop stage wise sunshine hours during high rice yield (>4500kgha-1) years. Sandhu et al., 2013, Ludhiana.
VEGETATIVE STAGE Effect of Relative Humidity:  Relative humidity is a function of temperature and moisture in the atmosphere is invariably much more in the morning than in the afternoon.  Rice- RH of 80-85% is ideal for shoot growth.  Root dry weight production was more influenced by RH than shoot dry weight. The root-shoot dry weight of plants at 90% was lowest at low temperature but higher at high temperature than in plants grown at 60% RH.  At 60% RH- decrease in moisture content, loss of chlorophyll and faster senescence of leaf.  High relative humidity with high solar radiation positively influenced the number of leaves per plant.  Low relative humidity shortened the days taken from transplanting to panicle initiation .
RIPENING STAGE  Low relative humidity (around 43%) during grain formation with a temperature range of 12-13 ºC was conducive to yield increase.  Relative humidity showed a negative relationship with panicles m-2, grains m-2, percentage of filled grains and grain yield but in non- significant manner.  The minimum relative humidity required for flowering of rice was 40%; the optimum being 70-80%.  If the RH is below 40%, flowering is inhibited .  In areas with high temperature and low relative humidity or low temperature with high humidity, glume did not open and finally resulted in poor viability of pollen.
Fertile spikelets ratio Variety 36/30oC 34/30oC 32/24oC 30/24oC RH(85%) RH(60%) RH(85%) RH(60%) RH(80%) RH(80%) IR 36 11.4 61.0 66.9 80.6 77.5 94.4 IR 24 22.6 66.4 39.2 65.1 76.5 94.3 Hinohikari 23.3 69.2 67.3 85.4 85.7 94.6 Yumehikari 44.4 80.8 59.4 78.4 76.5 98.2 Average 25.4 69.4 58.2 77.4 79.0 95.4 Table No.13: Fertile spikelet ratio of different varieties of indica and japonica rice exposed to different daytime air temperatures and RH levels. Shah et al., 2011, China.
Fig-5: Temperature Vs. Relative Humidity relationship
EFFECT OF WIND: VEGETATIVE STAGE Wind velocity at tillering stage had a positive significant correlation with grain yield; the effect with straw yield was positive but was non-significant. Strong winds caused leaf breakage and delay in crop maturity .  Wind speed during active tillering to heading stage had a significant negative correlation with number of panicles per plant and straw yield. REPRODUCTIVE STAGE  The 88 cm tall rice var. ‘CR 1009’ (170 d) lodged to 80-85º (displacement from the vertical) due to 8-9 kmph (24 h mean) wind at flowering stage during kharif season resulting in 63% panicle grain sterility and heavy loss in grain yield. Grain yield was more affected than straw yield due to wind at this stage. Strong winds at the time of the flower opening may induce
RIPENING STAGE Strong winds during the ripening period lead to the shredding of leaves, serious lodging and shattering of grains .  The occurrence of white grains was increased by wind at 14-21 days after heading .  Under strong winds, grain development and maturity were found to be poor. sterility and increase the number of abortive endosperms .  The anthers and ovaries were absent or desiccated due to prevalence of wind speed of 43-48 kmph.  Fertilization in rice was inhibited by wind speed of more than 4m/s.
Fig-6: The effect of separate plant parts on bending moment due to the wind force. (1) Whole plant (2) Plant without ear (3) Plant without leaf blade (4) Plant without ear and leaf blade Fig-7: The effect of separate plant parts on the bending moment due to the fresh weight of the plant. (1) Whole plant (2) Plant without ear (3) Plant without leaf blade (4) Plant without ear and leaf blade
 Among the abiotic stresses, weather plays the dominant role in influencing the growth and yield of rice.  If water is not the limiting factor, the most important weather parameters are temperature and solar radiation.  Rainfall (spatial and temporal variation) is the direct critical weather parameter in rainfed ecologies.  Relative humidity and wind velocity influence the crop growth to some extent.  Rice cultivation continues to be a risky enterprise, despite advances made in modern technologies.  The deviation in the weather can be exploited by resorting to optimum time of sowing or planting.  Spikelet fertility is the most sensitive yield component when rice is subjected to stress viz., low or high temperature, low solar radiation or water deficit (drought).
 Adjust the cropping schedule to reduce the risk of unfavorable weather condition during the reproductive and ripening stages.  For obtaining high yields, each and every phenophase of rice should enjoy the favourable weather conditions so as to put forth the best performance in obtaining the genetic yield dictated.
effect of different weather elements on growth and development of rice crop

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effect of different weather elements on growth and development of rice crop

  • 1. PROFESSOR JAYASHANKAR TELANGANA STATE AGRICULTURAL UNIVERSITY SUBMITTED BY: P.NANDINI, RAM/2018-09 SUBMITTED TO: Dr.G.SREENIVAS, PRINCIPAL SCIENTIST AND HEAD, ACRC,ARI,R. Nagar
  • 2. EFFECT OF DIFFERENT WEATHER ELEMENTS ON GROWTH AND DEVELOPMENT OF RICE CROP
  • 3. IMPORTANCE OF RICE  C3plant  90 %of the rice production- tropical/sub-tropical Asia -60 % of the world population lives.  Slogan- “RICE IS LIFE” -International Year of Rice 2004 -rice as primary source of food.  food security, poverty alleviation and improved livelihood.  staple food of over half of the world population .  Climate- the distribution of crops over different regions of the world.  weather - the potential production of the concerned crop.
  • 5. Vegetative Stage • Germination • Seedling Growth • Leaf Emergence • Plant height • Tillering Reproductive Stage • Panicle Initiation • Booting • Emergence of flag leaf • Heading • Flowering/Anthesis Ripening Stage • Maturity • Grain Filling • Grain Quality • Grain Weight GROWTH and DEVELOPMENT of RICE WEATHER ELEMENTS TEMPERATURE RAINFALL SOLAR RADIATION RELATIVE HUMIDITY WIND
  • 6. GROWTH STAGES OF RICE GERMINATION TILLERING PANICLE INITIATION HARVEST SEEDLING MAXIMUM TILLERING FLOWERING VEGETATIVE STAGE REPRODUCTIVE STAGE RIPENING STAGE
  • 7. Effect of Temperature: GERMINATION: Optimum temperature for germination is 20-35oC Low temperature depresses the rate of germination and prolongs it beyond the desirable span of 6 days. High temperature of 35 ºC or more halted the germination because of high respiration rate . VEGETATIVE STAGE
  • 8. Genotypes of Rice Temperature (oC) 12oC 16o C 20oC 25oC 27oC 30oC 33oC 36oC 40oC Sadri 0 80 92 94 95 98 93 65 0 Ahlami Tarom 0 93 97 96 100 96 92 72 0 Neda 0 92 97 94 100 98 96 70 0 Fajr 0 88 97 100 97 100 95 72 0 IR 42 0 65 91 86 97 98 94 62 0 Nearmat 0 80 95 96 93 99 95 68 0 IR 58 0 87 99 98 98 94 94 66 0 IR 8 0 66 93 92 99 96 93 64 0 Rashti 0 85 90 94 99 96 96 68 0 Salari 0 84 90 87 97 96 93 64 0 Table No.1: Effect of temperature on Germination percentages. Farhadi et al., 2012, Iran.
  • 9. SEEDLING GROWTH: Seedling growth rate increases linearly between 22-31oC ,suggesting that chemical reactions dominate growth and above 40oC the plant may die. SHOOT AND ROOT ELONGATION: Critical minimum temperature for shoot and root elongation i.e.,7-16 oC and 12-16oC respectively. Elongation is a combination of two components : cell division and cell enlargement and for which extreme temperatures are 15oC and 40oC. LEAF EMERGENCE: Before panicle initiation, leaf emerges about every 4-5 days, afterwards about 7-8 days. Temperature affects the rate of leaf emergence. Eg: When the rice plant is grown at 20oC, leaves emerge every 5 days. When it is grown at 25oC, they emerge every 4 days before panicle initiation. Bardhan and Biswas (1983)
  • 10. Mean temperature (oC) Leaves developed (no./main culm) Mean leafing rate (days/leaf)1st week 2nd week 3rd week 4th week 22 1.1 2.4 4.1 5.2 5.4 25 1.7 2.9 5.0 6.5 4.3 28 2.0 3.3 5.5 7.0 4.0 31 2.0 3.8 6.2 8.0 3.5 Table No.2: Leafing rate of IR-8 at different temperatures. Shouichi Yoshida, 1973, New Zealand.
  • 11. Table No.3: Mean dry weight and mean relative growth rate of four varieties at different temperatures. Mean temperature (oC) Dry Weight (g/plant) Relative growth rate (g.g-1.wk-1) 3rd week 4th week 0 to 3 weeks 3 to 4 weeks 22 0.09 0.29 0.45 1.15 25 0.23 0.74 0.75 1.18 28 0.26 0.89 0.78 1.25 31 0.30 1.08 0.83 1.28 Mean 0.22 0.75 0.70 1.21 Shouichi Yoshida, 1973, New Zealand.· Initial weight was 0.024 g.
  • 12. PLANT HEIGHT:  The plant height increased with the rise of temperature within the range of 30-35oC.  The plant elongates vigorously until 30 days after transplanting , then slowly ceases to elongate at the heading time. TILLERING:  Optimum temperature for tillering is 25-31 ºC.  Tillering rate is inhibited by low temperature, but the period of tillering is prolonged.
  • 13. Planting Date of Daily mean temperature from T-MT (OC) Duration in days T-MT Duration in weeks T-MT Degree days T-MT T MT D1 13/07 15/08 26.7 34 5 567 D2 27/07 30/08 26.3 35 5 569 D3 13/08 13/09 26.2 32 5 517 D4 11/01 06/03 22.9 55 8 707 D5 25/01 13/03 24.2 48 7 683 D6 04/02 21/03 25.8 46 7 725 D7 10/07 14/08 26.5 36 5 593 D8 25/07 28/08 27.1 35 5 599 D9 13/08 17/09 26.7 36 5 602 Mean 618+54 Table No.-4: Effect of temperature on duration of tillering and accumulated degree days in Kharif & Rabi. T-Transplanting: MT-Maximum tillering stage Lalitha , Raji Reddy, 1994-95, ARI, Rajendra Nagar
  • 14. Table No.5: Tiller number, dry weight, and relative growth rate of IR 8 at different temperatures during the period from 3 to 5 weeks after sowing. Mean Temperature (oC) Tiller no. Dry wt. (g) Mean relative growth rate (g.g-1.wk-1) 22 7.0 3.73 1.40 25 8.4 5.21 1.56 28 9.4 5.91 1.62 31 9.2 5.87 1.62 Shouichi Yoshida, 1973, New Zealand.Initial tiller number: 2.6, Initial dry weight: 0.24 g.
  • 15. Table No.6: Growth rate of IR 8 at different temperatures upto 5 weeks after sowing. Mean temperature (Oc) Growth rate Ratio of growth rate 0 to 1 wk (mg.plant-1. wk-1) 1 to 2 wk (g.g-1.wk-1) 2 to 3 wk (g.g-1.wk-1) 3 to 5 wk (g.g-1.wk-1) 0 to 1wk 1 to 2wk 2 to 3wk 3 to 5wk 22 8.1 1.16 1.16 1.40 1.0 1.0 1.0 1.0 25 10.7 1.53 1.40 1.50 1.3 1.3 1.2 1.1 28 13.7 1.51 1.35 1.62 1.7 1.3 1.2 1.2 31 15.7 1.52 1.39 1.62 1.9 1.3 1.2 1.2 Shouichi Yoshida, 1973, New Zealand.
  • 16. REPRODUCTIVE STAGE PANICLE INITIATION: After active tillering stage ,high temperatures decreases the number of panicles , panicle weight especially at maturity. BOOTING AND HEADING:  When the rice plant is subjected to low temperatures for 3days , it is more sensitive at the booting stage than heading, as indicated by the higher percentage of spikelet sterility.
  • 17. SPIKELET STERILITY LOW TEMPERATURE HIGH TEMPERATURE The critical temperature for inducing spikelet sterility varied from 10 to 15 ºc. Cool weather causes panicle sterility by interfering with pollen grain formation.  Observed that the temperature and sterility had a negative correlation which indicated lower temperature induced high sterility. Stated that the reduced yield was a result of poor pollen shedding as well as inadequate pollen growth in temperature above about 34ºC. High temperature desiccated pollens . The high sterility may be attributable to failure of fertilization caused by the imperfect splitting of anther or wilting of stigma induced by high temperature and low humidity.
  • 18. Fig-1: Effect of Temperature on yields of Rice World journal of Agricultural Research,2018,AP
  • 19. RIPENING STAGE GRAIN FILLING,GRAIN QUALITY,GRAIN YIELD: Optimum temperature for ripening is 20-25 ºC. Low temperature reduced the grain dry matter increasing rate, extends the grain filling, delays grain maturation although moderate cool temperatures sometimes benefits grain yield .  High temperature decreased the grain yield significantly due to the reduction of percentage of ripened grains. FLOWERING: The optimum was 25-30oC. Yoshida(1981) observed that a 13 day delay in flowering for each degree drop in temperature between 24oC and 21oC inIR 26 rice cultivars. Higher temperature(both maximum and minimum) and lower diurnal variation in temperature are more conducive for early flowering in rice varieties.
  • 20. Growth characteristics Mean temperatures (oC) 22 25 28 31 Days to flowering 140 127 118 131 Leaves developed (no./main culm) 19.5 20.2 20.5 21.7 Culm length 52.3 58.1 57.8 49.0 Flag leaf length (cm) 37.7 39.7 57.0 53.9 Flag leaf width (cm) 1.6 1.7 1.6 1.3 Dry weight of straw (g) 4.90 4.37 4.23 3.77 Dry weight of panicle (g) 1.98 1.72 1.66 0.76 Spikelets (no./ panicle) 272 227 207 157 Relative spikelet number 100 83 76 58 Table No.7: Growth characteristics and number of spikelets of IR 8 grown at different temperatures. Shouichi Yoshida, 1973, New Zealand.
  • 21. CROP STAGE AMBIENT TEMPERATURE ELEVATED TEMPERATURE(2oC) ELEVATED TEMPERATURE(4oC) TOTAL DAYS DAYS TAKEN FOR PHENOLOGICAL STAGE TOTAL DAYS DAYS TAKEN FOR PHENOLOGICAL STAGE TOTAL DAYS DAYS TAKEN FOR PHENOLOGICAL STAGE Sowing Transplanting 20 20 20 Active Tillering 41 21 40 20 39 19 Panicle Initiation 53 12 51 11 50 11 Flowering 70 17 67 16 65 15 Maturity 108(A) 38 102(B) 35 96(C) 31 D(A-B)=6days, E(A-C)=12days Table No. 8: Effect of elevated temperature (2oC and 4oC) over ambient on duration of phenological stages of rice during Kharif. Arthi Rani and Maragatham, 2012, ACRC,TNAU
  • 22. Growth stage Ambient Temperature Elevated Temperature (2oC) Elevated Temperature (4oC) Active Tillering 347.2 367.4 383.6 Panicle Initiation 209.8 214.9 236.0 Flowering 333.5 353.7 368.6 Maturity 633.0 646.8 653.0 AGDD (Transplanting to Harvest) 1523 1583 1641 Table No.9: Effect of elevated temperature (2oC and 4oC) over ambient on Accumulated Growing Degree Days (AGDD) during Kharif. Arthi Rani and Maragatham, 2012, ACRC,TNAU
  • 23. Fig-2: Effect of elevated temperature over ambient with AGDD on yield during Kharif 2012. Arthi Rani and Maragatham, 2012, ACRC,TNAU
  • 24. Effect of Rainfall:  Rainfall amount and distribution is the most critical weather component in rainfed rice ecologies (Upland, lowland and flood prone).  Its effect on irrigated ecology is indirect through availability of water in irrigation sources (tank, canal, well etc.,)  Daily rainfall is more critical than monthly or annual rainfall. A rainfall of 100 mm/month distributed evenly during the growing period was preferable than 200 mm/month, which fell in two or three days.  High rainfall during the active growth period resulted in taller plants and they lodge and decay in standing water.  TILLERING: In rainy season , is continued up to 42-45 days, whereas it is up to 50-55 days in dry season.  Total rainfall during nursery stage was negatively correlated with grain yield in non-significant manner but with straw yield it was significant and positively correlated. VEGETATIVE PHASE
  • 25. Water deficit during the vegetative stage reduces the PLANT HEIGHT, TILLER NUMBER AND LEAF AREA but the crop can recover without much loss in yield if water is available before flowering.  Low yield was obtained due to continuous rain coupled with strong wind at flowering in wet season.  Due to heavy rainfall, panicles have large number of blank florets .  Moisture stress after 10 days of 50 % flowering significantly reduced single PANICLE WEIGHT, TEST WEIGHT, FERTILE SPIKELETS PER PANICLE, TOTAL SPIKELETS PER PANICLE AND SPIKELET DENSITY and significantly increased sterile spikelets per panicle.  QUALITY: muddy or turbid water inflicts a greater damage to plants than clear water because sediments in turbid water block the pores in the plant body and hamper the respiration and photosynthesis process.
  • 26. RIPENING STAGE  Negative correlation between yield and number of rainy day during maturity phase.  Wet spells are detrimental to rice crop from flowering to maturity.  Deficit soil moisture during grain filling stage drastically reduces the grain yield even if there was normal rainfall during preceding phases. Yield variations are largely due to rainfall received during the grain filling stage of the crop. The beneficial influence persisted even when this factor was taken jointly with other climatic elements namely mean temperature and sunshine.
  • 27. Fig-3: Sensitivity of rice yields to rainfall receipt Indian Agricultural Research Institute , Kharif 2012,New Delhi
  • 28. S.No. Year Rainfall(mm) No. of rainy days Duration (days) Grain Yield (Kg ha-1) 1 1971 1573.1 63 103 753 2 1972 1344.4 34 79 463 3 1973 1320.1 61 104 417 4 1974 835.4 37 54 343 5 1975 1349.3 57 86 799 6 1976 978.0 50 73 513 7 1977 1729.2 53 84 1000 8 1978 1250.1 60 105 738 9 1979 467.2 26 56 13 10 1980 1551.0 56 95 526 11 1981 669.8 39 102 354 12 1982 1273.9 50 68 515 13 1983 1271.1 52 108 700 14 1984 1443.2 48 100 360 Table No.10: Rainfall features during monsoon months and yield of rainfed rice during (1971-1996).
  • 29. S.No. Year Rainfall(mm) No. of rainy days Duration (days) Grain Yield (Kg ha-1) 15 1985 1471.4 56 80 801 16 1986 1097.1 65 89 234 17 1987 1123.4 45 77 629 18 1988 1011.8 50 98 663 19 1989 685.0 46 102 490 20 1990 1708.9 66 107 868 21 1991 1334.6 48 94 570 22 1992 1050.2 47 86 693 23 1993 1428.9 60 108 716 24 1994 2052.0 60 98 799 25 1995 1170.8 44 71 778 26 1996 658.7 44 68 593 (contd…………) Gupta et al., 2000, Jabalpur.
  • 30. Effect of Solar radiation: VEGETATIVE STAGE  Rice yield during summer season becomes almost double of that of monsoon season in eastern and southern India whereas it increases marginally in Punjab.  Sunshine in a week prior to transplanting and the two weeks period coinciding with the grand period of elongation was conducive for better yield .  LAI reduced to a greater extent in plants shaded from planting to panicle initiation.  Shading(45-50 % reduction in sunlight) delayed tillering and decreased tillering rate.  Irrespective of varieties, shading increased the plant height, LAI and total chlorophyll content and significantly reduced the tiller number and total dry matter production  In long duration varieties, low light stress synchronizes with the vegetative lag phase results in considerable tiller mortality and fewer panicles m-2 .
  • 31.  Solar radiation and Temperature during reproductive stage (before flowering) had the greatest influence on rice yield because they determine the number of spikelets m-2.  Higher accumulated solar radiation from transplanting to flowering resulted in more panicles m-2.  Leaves grown in low irradiance are thinner than the leaves of plants grown in higher irradiance.  The most critical sunlight requiring period was around the heading stage. During this period, a mean yield reduction of 6.5% was observed for every 1 % reduction in solar radiation.  Low light stress reduced grain number panicle-1 in short duration varieties, increased spikelet sterility in medium duration varieties and decreased panicle number in long duration varieties .
  • 32. RIPENING STAGE  The yield attributes and grain yield recorded a positive correlation with solar energy during ripening stage.  Low light causes spikelet sterility, dry matter is reduced , weak and unproductive tillers, proline content decreases in the panicle .  Proline deficiency in the spikelet's may also be a factor in high sterility .  Dry matter accumulation during post flowering was more in dry than in wet season during ripening stage, which was due to higher solar radiation and demand of developing sink .  Cumulative solar radiation of 14,000 g cal cm-2 and 200 hours of sun shine during 30 days preceding to harvesting is optimum for obtaining maximum grain yield.
  • 33. Fig-4: Peak stages of solar radiation requirement in Rice International Journal of Applied Research, 2015.
  • 34. Crop growth phase Normal 2000 2001 2010 2011 Vegetative stage 609 529(-13%) 526(-13%) 498(-18%) 508(-16%) Reproductive stage 401 462(-15%) 454(13%) 304(-24%) 284(-29%) Transplanting to Physiological Maturity 1010 991(-1.9%) 980(-2.9%) 802(-20.6%) 792(-21.6%) Table No.-11: Crop stage wise sunshine hours during low rice yield(<4000kg ha-1) years. Sandhu et al., 2013, Ludhiana.
  • 35. Crop growth phase Normal 2004 2005 2007 2009 Vegetative stage 609 608(-0.1%) 612(0.4%) 568(-6%) 669(9%) Reproductive stage 401 419(4%) 415(3%) 340(-15%) 391(-0.02%) Transplanting to Physiological Maturity 1010 1027(1.7%) 1027(1.7%) 908(-10.1%) 1060(4.9%) Table No.-12: Crop stage wise sunshine hours during high rice yield (>4500kgha-1) years. Sandhu et al., 2013, Ludhiana.
  • 36. VEGETATIVE STAGE Effect of Relative Humidity:  Relative humidity is a function of temperature and moisture in the atmosphere is invariably much more in the morning than in the afternoon.  Rice- RH of 80-85% is ideal for shoot growth.  Root dry weight production was more influenced by RH than shoot dry weight. The root-shoot dry weight of plants at 90% was lowest at low temperature but higher at high temperature than in plants grown at 60% RH.  At 60% RH- decrease in moisture content, loss of chlorophyll and faster senescence of leaf.  High relative humidity with high solar radiation positively influenced the number of leaves per plant.  Low relative humidity shortened the days taken from transplanting to panicle initiation .
  • 37. RIPENING STAGE  Low relative humidity (around 43%) during grain formation with a temperature range of 12-13 ºC was conducive to yield increase.  Relative humidity showed a negative relationship with panicles m-2, grains m-2, percentage of filled grains and grain yield but in non- significant manner.  The minimum relative humidity required for flowering of rice was 40%; the optimum being 70-80%.  If the RH is below 40%, flowering is inhibited .  In areas with high temperature and low relative humidity or low temperature with high humidity, glume did not open and finally resulted in poor viability of pollen.
  • 38. Fertile spikelets ratio Variety 36/30oC 34/30oC 32/24oC 30/24oC RH(85%) RH(60%) RH(85%) RH(60%) RH(80%) RH(80%) IR 36 11.4 61.0 66.9 80.6 77.5 94.4 IR 24 22.6 66.4 39.2 65.1 76.5 94.3 Hinohikari 23.3 69.2 67.3 85.4 85.7 94.6 Yumehikari 44.4 80.8 59.4 78.4 76.5 98.2 Average 25.4 69.4 58.2 77.4 79.0 95.4 Table No.13: Fertile spikelet ratio of different varieties of indica and japonica rice exposed to different daytime air temperatures and RH levels. Shah et al., 2011, China.
  • 39. Fig-5: Temperature Vs. Relative Humidity relationship
  • 40. EFFECT OF WIND: VEGETATIVE STAGE Wind velocity at tillering stage had a positive significant correlation with grain yield; the effect with straw yield was positive but was non-significant. Strong winds caused leaf breakage and delay in crop maturity .  Wind speed during active tillering to heading stage had a significant negative correlation with number of panicles per plant and straw yield. REPRODUCTIVE STAGE  The 88 cm tall rice var. ‘CR 1009’ (170 d) lodged to 80-85º (displacement from the vertical) due to 8-9 kmph (24 h mean) wind at flowering stage during kharif season resulting in 63% panicle grain sterility and heavy loss in grain yield. Grain yield was more affected than straw yield due to wind at this stage. Strong winds at the time of the flower opening may induce
  • 41. RIPENING STAGE Strong winds during the ripening period lead to the shredding of leaves, serious lodging and shattering of grains .  The occurrence of white grains was increased by wind at 14-21 days after heading .  Under strong winds, grain development and maturity were found to be poor. sterility and increase the number of abortive endosperms .  The anthers and ovaries were absent or desiccated due to prevalence of wind speed of 43-48 kmph.  Fertilization in rice was inhibited by wind speed of more than 4m/s.
  • 42. Fig-6: The effect of separate plant parts on bending moment due to the wind force. (1) Whole plant (2) Plant without ear (3) Plant without leaf blade (4) Plant without ear and leaf blade Fig-7: The effect of separate plant parts on the bending moment due to the fresh weight of the plant. (1) Whole plant (2) Plant without ear (3) Plant without leaf blade (4) Plant without ear and leaf blade
  • 43.  Among the abiotic stresses, weather plays the dominant role in influencing the growth and yield of rice.  If water is not the limiting factor, the most important weather parameters are temperature and solar radiation.  Rainfall (spatial and temporal variation) is the direct critical weather parameter in rainfed ecologies.  Relative humidity and wind velocity influence the crop growth to some extent.  Rice cultivation continues to be a risky enterprise, despite advances made in modern technologies.  The deviation in the weather can be exploited by resorting to optimum time of sowing or planting.  Spikelet fertility is the most sensitive yield component when rice is subjected to stress viz., low or high temperature, low solar radiation or water deficit (drought).
  • 44.  Adjust the cropping schedule to reduce the risk of unfavorable weather condition during the reproductive and ripening stages.  For obtaining high yields, each and every phenophase of rice should enjoy the favourable weather conditions so as to put forth the best performance in obtaining the genetic yield dictated.