Physiological and biochemical investigation on leaf reddening in bt and non bt cotton (Gossypium spp.)
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Date
2016-12-31
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Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola, Maharashtra.
Abstract
Cotton IS an 1111portant commercial fib re crop of global significance which plays a dominant role in world ag riculture ancl industri al economy. India is important grower of cotton on a global scale. Among the productionconstrai nts leaf reddening is the predominant problem of Bt cotton growers which became issue of debet for ascertaining the causes and remedies for leaf reddening.
To ascertain the role of nutrients in leaf reddening, the present field experiment entitled, "Physiological and biochemical investigation on leaf reddening in Bt and non Bt Cotton (Gossypium spp.)" was carried out at AICCP, experimental field of Cotton Research Unit, Dr. PDKV Akola, (M.S.) during Kharif season of 2013-14 and 2014-15 in split plot design replicated thrice. Main plot treatments consisted of three hybrids [viz., Mallika (Bt), RCH 2 (Bt) and PKV Hybrid 2 (non Bt)], sub plot treatments were two fertilizer doses [viz., 100% RDF and 125% RDF]. Sub-sub plot treatments consisted of seven different chemical sprays [viz., 2% Urea, 2% DAP, 2% KN03, 1% MgS04, 500 ppm Cycocel, irrigation and control]. Thus, 42 treatment combinations were formed. The fertilizer dose for Bt (120:60:60 NPK kg/ha)
and non Bt cotton (60:30:30 NPK kg/ha) was applied in two split doses. At the time of sowing 50% N and full dose of P and K was applied and remaining N was applied after 30 DAS. The two foliar sprays were given at 60 and 80 DAS. The recommended package of practices was. followed during course of investigation.
Besides the yield data, periodical observations on morphological (plant height, leaf area plant-1; dry matter plant-1 and red leaf incidence), physiological (photosynthetic efficiency and relative water content} and biochemical (cell sap pH, total chlorophyll, N, Mg, anthocyanin proline and carbohydrate content of leaf) parameters were recorded at 60, 80, 100 and 120 DAS. The Phenological observations were alsoc recorded Soil fertility status (available N, P and K) were recorded before sowing and after harvesting in both the years. The observations on sucking pest (number of leafhopper, aphids, thrips and whitefly leaf1) were also recorded. The experimental evidences pointed out that the incidence of leaf reddening was more in Bt cotton than non Bt colton. The minimum intensity of reddening in Bt and non Bt cotton was observed in the treatment combination of 125 % RDF +foliar sprays with KN03 and MgS04. Among the foliar sprays 2% KN03 (60 and 80 DAS) had shown minimum leaf reddening. However, the xiv treatment combination (125% RDF + 1 % MgS04) was found to be the best for highest total chlorophyll content. The study also revealed that the mineral nutrients, which were mostly responsible for reddening viz., nitrogen and magnesium content in leaves, were decreased as the crop growth stage advanced. The PKV Hybrid 2 ·recorded rna~imum cell sap pH, total chlorophyll, leaf nitrogen and magnesium content than the Bt cotton hybrids. In case of fertilizer dose, 125% RDF and foliar sprays of 2% KN03 and 1% MgS04 maintained higher cell sap pH, total chlorophyll, nitrogen, and magnesium content of leaves in non Bt cotton than Bt cotton. Accumulation of highest proline, anthocyanin and carbohydrate were found in reddening affected leaves. It was evident that, the application of 125% RDF showed 9.21 % reduction in leaf reddening incidence. Similarly 16.14% increased seed cotton yield per plant with application of 125% RDF over 100% RDF. Per cent
reduction of red leaf incidence was recorded 18.33% in 2% KN03 treated plot followed by 1% MgS04 i.e. 14.76% over control. Seed cotton yield per plant was Increased by 39.33% in 2% KN03 treated plot followed by 1% MgS04 sprayed plot i.e. 31.88% over the control (untreated plots). Application of 125% RDF and the two foliar sprays of 2% KN03 and 1% MgSO~ at 60 and
80 DAS had reduced the risk of leaf reddening as well as helped in increasing seed cotton yield in Bt and non Bt cotton hybrids at Akola conditions. It is concluded from the present study that th.e reduction In chlorophyll,
nitrogen and magnesium content in plant at boll development stage was the cause of reddening in Bt and non Bt cotton. This study also suggested that,
the nutrients were one of the causes for leaf reddening. Bt cotton had more nutrients requirement especially at boll development stage, which was fulfilled by the foliar sprays. Hence, present study also provides future guide line of research for various combinations of nutrients for foliar sprays for Bt cotton hybrids at different development stages, which can reduce leaf reddening and there by yield sustainability can be achieved.
Description
The present research was carried out during kharif season of the years, 2013-14 and 2014-15 at experimental field of Cotton Research Unit, Dr. P.D.K.V., Akola (M .S.) so as to find out the causes of leaf reddening in Bt and non Bt cotton and morphophysiological and biochemical changes taking place in the crop.
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Citation
RAUT SUMIT MURLIDHAR. (2016). Physiological and biochemical investigation on leaf reddening in bt and non bt cotton (Gossypium spp.). Department of Agricultural Botany, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola, Maharashtra.