Name of the author : Y. JANAKI RAMULU
Title of the thesis : IDENTIFICATION OF COTTON GROWTH
STAGES AND GROWTH PATTERN STUDIES IN
Degree : MASTER OF SCIENCE IN AGRICULTURE
Faculty : AGRICULTURE
Department : CROP PHYSIOLOGY
Chairperson : Dr. T. RAMESH
University : PROFESSOR JAYASHANKAR TELANGANA
STATE AGRICULTURAL UNIVERSITY
Year of submission : 2016
The present investigation entitled “Identification of cotton growth stages and growth pattern studies in cotton genotypes” was conducted at the college farm, College of Agriculture, Rajendranagar, Hyderabad, during kharif 2015-2016. The field trial was conducted following split plot design with three replications and three cotton genotypes viz. ADB-542, Narasimha and Deltapine 9121 as main plots, three different levels of spacings viz. 75 x 10, 60 x 10 cm and 45 x 10 cm as sub plots. To determine the duration for growth phases in cotton, requirement for photo induction of flowering to maturity the growth phases, yield attributes and yield. In this experiment, phenological observations (days to squaring, flowering, boll initiation and peak boll burst), growing degree days require ment for (squaring, flowering and boll initiation), morphological parameters (plant height, leaf area, number of monopodia, number of sympodia and dry matter production per plant), physiological parameters (leaf pigments, spad chlorophyll meter readings (SCMR), photosynthetic rate, chlorophyll stability index and proline), growth parameters (crop growth rate, relative growth rate, net assimilation rate, specific leaf area and specific leaf weight) and yield parameters (number of bolls per plant, boll weight, seed cotton yield, lint yield and seed index) were evaluated at three different growth stages.
Results of phenological characteristics showed that in 75 x 10 cm spacing, for square, flower and boll initiation minimum days were required (42.1, 66.8 and 93.4 respectively). Among the genotypes Deltapine 9121 recorded early square, flower and boll initiation i.e at 41.1, 66.6 and 92.3 days respectively. Minimum days were required for peak boll burst in Deltapine 9121 at 75 x 10 cm (114.0 days). In 75 x 10 cm minimum growing degree days (GDD) were required for squaring (740), flowering (1148) and boll initiation (1588). Among the genotypes Deltapine 9121 recorded minimum GDD for early squaring (722), flowering (1144) and boll initiation (1570).
Morphological parameters showed that Deltapine 9121 recorded maximum plant height (78.1 cm) in 75 x 10 cm spacing and Narasimha recorded minimum plant height (48.3 cm) in 45 x 10 cm at boll initiation stage. Significantly maximum leaf area (3489cm2) in 75 x 10 cm was recorded in Deltapine 9121 while, Narasimha showed minimum leaf area at boll initiation stage (773 cm2). Deltapine 9121 showed significantly maximum number of sympodia at 75 x 10 cm spacing (17.3), while, Narasimha at 45 x 10 cm spacing recorded minimum sympodia (11.6). Deltapine 9121 also showed significantly maximum number of monopodia at 75 x 10 cm spacing (1.3). Deltapine 9121 at 75 x 10 cm spacing had recorded maximum dry matter production (90.1 g).
In respect of physiological parameters Deltapine 9121 recorded maximum leaf chl-a (1.11 mg g-1), chl-b (1.77 mg g-1), chl-t (3.11 mg g-1) and carotenoids (0.68 mg g1), SCMR values (29.1), photosynthetic rate (23.6 μ mol CO2 m-2s-1), chlorophyllstability index (49.3 %) and proline (933 μg g-1 fresh weight) in 75 x 10 cm spacing at boll initiation stage. While, Narasimha recorded minimum leaf chl-a (0.43 mg g-1), chlb (0.46 mg g-1), chl-t (0.91 mg g-1) and carotenoids (0.20 mg g-1), SCMR values (39.2), photosynthetic rate (13.2 μ mol CO2 m-2s-1), chlorophyll stability index (25.2 %) andproline (281 μg g-1 fresh weight) in 45 x 10 cm respectively at boll initiation stage.
At 60-90 DAS the crop growth rate (CGR) was significantly maximum in Deltapine 9121 at 75 x 10 cm spacing (1.81 g day-1). Narasimha at 60 x 10 cm spacing showed maximum RGR i.e. 0.037 g g-1 day-1 at 40-60 DAS. At 40-60 DAS maximumNAR (0.001 g cm-2-1) was recorded in 75 x 10 cm spacing in genotype Narasimha(0.001 g cm-2d-1), 60 x 10 cm spacing all the tested genotypes and in 45 x 10 cm spacing all the tested genotypes recorded the similar rate of assimilates. Specific leafarea was maximum in Deltapine 9121 at 75 x 10 cm spacing (126 cm2g-1) and minimum in Narasimha at 75 x 10 cm spacing (80 cm2
g-1) at 90 DAS. Specific leaf weight was maximum in Narasimha at 75 x 10 cm spacing (0.012 g cm-2) and minimum in Deltapine 9121 at 75 x 10 cm spacing (0.008 g cm-2
) at 90 DAS.
Deltapine 9121 at 75 x 10 cm spacing recorded maximum number of bolls i.e. 7.9, boll weight 2.90 g, seed cotton yield 23.17 g plant-1 and lint yield 826 kg ha-1