Search

Background: Red spider mite, Tetranychus truncatus Ehara (Acari: Tetranychidae) infests many agriculture and horticulture crops in India, but to date it had not been found damaging cultivated groundnut. During 2022-23, the incidence of this species was high in many groundnut growing regions of Tamil Nadu. Identification of the species is highly essential for effective management of the particular pest. Hence, the aim of this research was to identify the mite species infesting groundnut crop and describe the damage caused. Methods: Survey was carried out all over Tamil Nadu and samples of mite infested groundnut leaves were collected from field based on damage symptoms, observed and examined under Stereo zoom microscope, microslides were prepared using Hoyer's medium and taxonomic characters were studied under phase contrast microscope. Molecular analysis was done by genomic DNA isolation, PCR amplification, sequencing and BLAST performed to check the identity with GenBank Sequences. ITS2 primer was used. Result: Red spider mite species, T. truncatus was identified first time in groundnut through both morphological characters and molecular tools. Female: Idiosomal setae longer than the interval between their longitudinal bases and gradually tapers distally. Diamond-shaped pattern of striae between e1 and f1 setal bases. Tarsus I with 4 tactile setae proximal to proximal duplex setae. Male: Aedeagus with tiny terminal knob, apparently truncate with a slight indentation on the dorsal margin. [ABSTRACT FROM AUTHOR]

An experiment on response of rice to nitrogen under aerobic and transplanted conditions was conducted in split-split -plot design with two methods of rice cultivation, seven rice varieties and five nitrogen levels. The grain yield was significantly higher in transplanted rice compared to aerobic rice. Significantly higher grain yield was observed with MTU 1001 and MTU 1010 as compared to IR 64, Tella hamsa and Rajendra and the grain yield in the former two varieities was comaparable with Naveen and Erramallelu. Increase in grain yield with every 100 kg of N ha-1 from 100 kg to 300 kg ha-1 was significant. Significant interaction effect on grain yield was observed due to method of crop establishment, varieties and nitrogen levels. Aerobic rice received 627 mm of irrigation water as compared to 1228 mm in transplanted rice and the mean water productivity was higher under aerobic rice (0.49 kg grain m-3) as compared to transplanted rice (0.31 kg grain m-3). [ABSTRACT FROM AUTHOR]

The field experiments were conducted to study the available N,P,K and S in soil with the effect of Panchagavya made from cow (PK-C) and buffalo (PK-B) products sprayed to plants and applied to soil with different concentrations (3 and 5 per cent to plant and 9 and 15 per cent to soil) at different intervals (3 sprays - 30, 60 and 90 DAS; 4 sprays - 20, 40, 60 and 80 DAS) during rabi 2007-08 and kharif 2008. The available nutrients viz., N, P, K, and S was highest with PK-C @ 15% to soil (T10) but it was at par with soil application of PK-B @ 15% to soil and PK-C @ 5% - 4 sprays. [ABSTRACT FROM AUTHOR]