V. VISALAKSHMI*, K. MADHU KUMAR, A. UPENDRA RAO AND N. HARI SATYANARAYANA
Agricultural Research Station, Amadalavalasa, Srikakulam, Andhra Pradesh
Thirty six early duration rice varieties were evaluated during kharif, 2015 under natural field conditions for resistance to stem borer and their yield potential in late sown situation. The highest incidence of stem borer as per cent white ears was recorded in TN1 (19.48%) which was the susceptible check, whereas, two varieties were found to be highly resistant with 0 scale (incidence less than 1.0% WE), twenty five varieties, were found to be Resistant with scale ‘1’ (incidence ranged between 1.0-5.0% WE) and eight varieties were moderately resistant with scale’3’ (incidence ranged between 6.0-10.0% WE). A significant positive correlation was observed between no. of panicles and grain yield (r= 0.39). As per the study, NLR40024 was the most suitable variety for North Coastal Zone of Andhra Pradesh with 6164 kg ha-1 grain yield along with high resistance to stem borer at reproductive stage under late sown conditions on puddled soil.
Rice, Early duration, Yellow stem borer, white ears
Rice (Oryza sativa L.) is one of the most significant cereal crop and is the staple food for more than 2 billion people. Almost 90 per cent of the rice is grown and consumed in Asia. India is the second largest rice producing country in the world. In India rice occupies about 44.6 million hectares with a production of 90 million tons (Ghule et al., 2008) and constitutes 52 per cent of total food grain production.
Yellow stem borer, Scirpophaga incertulas (Walker), (Lepidoptera: Pyralidae), a monophagous pest of paddy is considered as most important nuisance of rain fed low land and food prone rice ecosystems (Deka and Barthakur, 2010). It is one of the major pests in all rice producing areas of the world. During the reproductive stage, the larvae feeds on the stem particularly in panicle initiation and earhead emergence stage, causing ‘white ear’ symptoms and with heavy infestation, resulting profound loss in yield (Sarwar, 2012). At present, farmers frequently use chemical pesticides for the control of this pest (Kudagamage and Nugaliyadde, 1995). Reliance on use of insecticides leads to numerous undesirable consequences to ecosystem and also hazardous to human beings. To manage this pest menace, the approach of varietal resistance which is less expensive, eco-friendly and can be easily fitted in the integrated pest management is one of the solution for lowering the pest incidence.
Late sown condition was most prevalent in North Coastal Zone of Andhra Pradesh due to late release of water through canals to cater the irrigation needs of canalfed, rainfed and tankfed situations. During this situation, growing of medium and short duration varieties is the best option to get good yield with limited time and water, also to get additional income through rice fallow pulses. Hence the trial was taken to identify the suitability of released short duration varieties to this area and under this situation, yellow stem borer was a problem at reproductive stage which directly reduce the yield. Hence, the information on resistance to yellow stem borer was also recorded in order to screen the best suitable variety along with resistance to stem borer.
Thirty six short duration varieties during kharif 2015 were supplied by Indian Institute of Rice Research, Rajendranagar, Hyderabad were directly sown on puddle soil during 1st week of September 2015 at a spacing of 15
× 15cm, dibbled 2-3 seeds per hill in 5 × 5 m plots each in Randomized Block Design with three replications under natural field conditions at Agricultural Research Station,
Ragolu, Srikakulam district in Andhra Pradesh. No plant protection coverage was provided in the test material to create optimum condition for pest multiplication. All the recommended agronomic practices were adopted during the period of experimentation. Incidence of stem borer was recorded on all the 20 hills per plot in stratified random sampling method at preharvest stage. The total tillers and number of white ears at pre harvest stage were noted and per cent white ears were worked out. Yield and yield attributes such as days to 50% flowering, plant height, no. of panicles/sq.m and net plot yield were also recorded. The data was subjected to appropriate statistical analysis after transformation.
Total no. of white ears
% white ears = Total ear bearing tillers 100Based on the damage rating and scale, the status of rice varieties were determined by the following IRRI Standard Evaluation System (SES) for rice.
Under natural field conditions, data on per cent white ears collected during pre-harvest stage was assessed in thirty six popular short duration varieties of rice. The results indicated that the two popular short duration varieties NLR 40024 (0.11% WE) and Erramallelu (0.34% WE) exhibited high resistance with ‘0’ scale where as the highly susceptible variety TN1 recorded 19.48%WE which comes under scale ‘7’ i.e susceptible. Twenty five varieties viz., Sahghagidhan (1.9% WE), CR Dhan 201(3.34% WE), CR Dhan 101(1.88% WE), DRR Dhan 43 (IET 22080) (5.4%WE), CR Dhan 204 (1.33% WE)), Cotton Dorasannalu (MTU1010) (5.4%WE), DRR Dhan 44 (IET 22081) (5.73%WE), Vandana 3.48%WE), CR Dhan 202 (2.84%WE), Govind (3.71%WE), Tripura Khara Dhan 1 (IET 22837) (2.5%WE), CR Dhan 100 (2.39), IET 23356 (4.84 %WE , PR 124 (2.95% WE),
IET 23420 (4.37% WE), Tulasi (1.31% WE), Anjali (2.32%WE), CR Dhan 103 (2.3% WE), KMP 105 (2.38%WE), CR Dhan 40 (4.31% WE), JGL 17004 (3.31% WE), JGL 11118 (4.89% WE), NLR 34449 (2.9% WE), Indira Aerobic 1 (4.37% WE )and Samaleshwari (3.52% WE) were resistant with ‘1’ scale. Seven varieties DRR Dhan 42 (IR 64 Drt-1) (IET 22836) (7.75% WE), Narendra 97 (6.31% WE), CR Dhan 203 (10.1% WE), CR Dhan 205 (7.78% WE), Tripura Khara Dhan 2 (IET 22835) (8.12% WE), IR 64 (10.65%WE), Luit (6.31% WE), Varalu (10.1% WE) and RNR 15048 (7.36% WE ) were moderately resistant with ‘3’ scale of Standard Evaluation system of IRRI.
A significant positive correlation was observed between number of panicles and yield (0.3851). A negative correlation was observed between per cent white ears and yield was not significant (-0.0831).
NLR40024 was most suitable variety for North Coastal Zone of Andhra Pradesh with 6164 kg ha-1 yield coupled with high resistance to stem borer at reproductive stage, CR Dhan 203 recorded similar yield but was found to be moderate resistance to stem borer. PR 124 was next best short duration variety with 5701 kg ha-1 yield followed by IET 23420 with 5509 kg ha-1 yield, Tripura Khara Dhan 1 (IET 22837) with 5450 kg ha-1, CR Dhan 100 with 5351 kg ha-1, DRR Dhan 44 (IET 22081) with 5284 kg ha-1 with scale ‘1’ i.e resistance even though they were sown late in the season directly on puddled soil during 1st week of September. The present results are also in conformity with the findings of IIRR Progress report (2015).