Aims: To conduct studies on non-preference mechanism and biochemical aspects of resistance to BPH on resistant rice genotype.
Study Design: Completely Randomized Design.
Place and Duration of Study: Poly-house, Department of Entomology, Rice Research Centre, Agriculture Research Institute (ARI), Rajendranagar, Hyderabad, India, between June 2017 and May 2018.
Methodology: The selected rice entries were selected including PTB33 (resistant check) and TN1 (susceptible check), this was replicated thrice. After 30 days, about hundred first instar nymphs were released in the pots. The number of nymphs settled on each entry was counted from randomly selected 10 hills at 24, 48, 72, 96 and 120 hours after release. Number of probing marks made by a day old single female insect during 24 hours of its feeding was recorded on all the selected entries along with resistant and susceptible rice cultures. Estimation of total phenols, total sugars and proteins was done for selected rice genotypes.
Results: Among all the test cultures, KNM 2305, KNM 2307, JGL 24423 and Sabita recorded lowest number of nymphal settlement. Biochemical aspects of resistance like total phenols, total sugars and protein content in selected rice genotypes was done. The amount of total phenol was observed to be maximum in the leaf sheath of moderately resistant JGL 24423 (2.70 mg/g). The amount of total sugars was lowest in RNR 26111 (0.33 mg/ g), RNR 21571(0.86 mg/g) followed by JGL 24423 (1.40 mg/g) and highest in susceptible check TN-1 (2.97 mg/g). Least amount of protein was observed in JGL 24423 (0.76 mg/g) followed by IET 23993 (1.43 mg/g).
The promising high yielding rice genotype, KNM 1638 is a medium slender, early duration (120 –125 days) and photo insensitive culture with high yield potential (7356 kg ha-1) having resistance to gall midge and leaf blast, and moderately resistant to neck blast with better adaptability. This rice culture KNM 1638, a derivative of the cross JGL 11727×JGL 17004 was released through State Varietal Release Committee on the name of Kunaram Vari 2 for Telangana state during the year 2021 as an alternate variety to BPT 5204. It has semi-dwarf plant type with moderate tillering, semi-erect flag leaf, all plant parts green, semi-compact well exerted semi-erect attitude of branching panicle, straw-colored awn less grains and its grain classified as a translucent medium slender grain. In the overall performance, KNM 1638 recorded mean productivity of 7356 kg ha-1 in the eight years of trials with 12.8% increase over the check varieties. It has good grain, cooking and eating quality, and good marketing facility as quality-wise it recorded 63% head rice recovery and 21.47% amylose content with soft gel consistency and moderate gelatinization temperature. The rice variety, KNM 1638 is suitable for cultivation during kharif, late kharif and rabi seasons throughout Telangana State with higher yield, better pest and disease resistance and good cooking quality in comparison to the check varieties.
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