ROOT INFLUX OF NUTRIENTS AND YIELD OF BT. COTTON CULTIVARS AS INFLUENCED BY POTASSIUM LEVELS
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Date
2011-07
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jau,junagadh
Abstract
A pot experiment was conducted at the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Junagadh Agricultural University, Junagadh during year 2006-07 to study "Root Influx of Nutrients and Yield of Bt. Cotton Cultivars as Influenced by Potassium Levels", whereas the field experiment was conducted at the Instructional Farm of the College of Agriculture, J.A.U., Junagadh to study "Effect of Cultivars and Potassium on Yield of Bt. Cotton" during year 2007-08. The object was to assess the effect of variety and potassium on dry matter yield, concentration and uptake of nutrients, root influx of NPK, yield attributing characters, yield and quality of Bt. cotton and soil available nutrients.
For pot experiment, total 20 treatment combinations consisting of five Bt cotton varieties approved by Government of Gujarat / India and four levels of K(0, 80,120 and 160 kg ha-1) and replicated thrice for each stage were tested. While, total 15 treatment combinations comprised of five Bt cotton variety (As per pot experiment) and three levels of potassium (0, 80, 120, kg ha-1) were tested under field condition and replicated four times.
Under pot experiment, the dry matter yield of shoot, root and total plant at 30, 60, 90 and 120 days were influenced significantly by different varieties viz., Ankur-165, Vikram-5, Shakti-7, Rashi-2 and Mico-162 of Bt. cotton. Almost, the dry matter yield of shoot and root parts of plant and total plant dry matter recorded highest values with a variety V4 (Rashi-2) followed by Mico-162. The dry weight of all growth parameters increased with increasing levels of potash at all the growth periods. The cumulative dry weight of the plant was increased with age of plant. The maximum dry matter accumulation was obtained onwards to 90 days to till maturity.
The concentrations of nitrogen, phosphorus and potassium in shoot, root and in seed cotton did not influenced significantly by varieties of Bt. cotton. The concentration of K in the shoot and root at 30, 60, 90 and 120 days increased with increasing levels of potassium application. The concentration of potassium in seed cotton was higher at 160 kg K2O ha-1, while, the concentration of nitrogen and phosphorus was not influenced by potassium application. The average concentration of nitrogen in shoot and root of Bt. cotton was 2.52 and 0.89 % at 30 days, 2.32 and 0.84 % at 60 days, 1.93 and 0.98 % at 90 days and 1.54 and 0.88 % at 120 days growth period, respectively.
The uptake of nitrogen, phosphorus and potassium by shoot and root of plant and their total uptake at different growth stages as well as by seed cotton was influenced significantly by varieties of Bt. cotton except NPK uptake at 30 and 90 days of growth. Almost, the maximum uptake of nitrogen, phosphorus and potassium by shoot and root of plant and their total uptake was recorded with variety V4 (Rashi-2). The uptake of NPK by shoot, root and their total uptake at different growth stages recorded significantly higher under the application of potash @ 160 kg ha-1. The average total uptake (g plant-1) of nitrogen was 0.176, 1.223, 2.684 and 5.758, phosphorus was 0.017, 0.131, 0.282 and 0.413 and potassium was 0.112, 0.884, 2.441 and 2.798 g plant-1 at 30, 60, 90 and 120 days of growth, respectively.
At initial stages (30 DAS), the variety V2 (Vikram-5) showed higher values of root radius and root volume whereas the root length was higher with variety V4 (Rashi-2). Almost, all root parameters were higher with variety V4 i.e. Rashi-2 in advanced stages. Root parameters like root radius, root volume and root length were affected significantly by potassium level at all growth stages except the root length at 90 and 120 DAS but exhibited inconsistent trend with potassium level. Root influx of nitrogen, phosphorus and potassium as influenced by the varieties of Bt. cotton at 30-60 and 90-120 days growth period were recorded higher with variety V4 (Rashi-2) but remained unaffected at 60-90 DAS. The application of K produced significant effect on root influx of N, P and K at 30-60 DAS and K at 90-120 DAS, while root influx of N, P and K at 60-90 DAS remained unaffected. The root influx of nitrogen, phosphorus and potassium was observed in range of 7.94 – 14.82 (N x 10-7), 1.24 – 3.34 (P x 10-7) and 10.60 – 19.91 (K x 10-7) mg cm-1 sec-1 at 30-60, 60-90 and 90-120 days growth period. The root influx of K was recorded maximum at 30-60 days (initial stage) as compared to both later stages (60-90 DAS and 90-120 DAS) of crop.
Among the various varieties, the variety V4 (Rashi-2) showed higher number of sympodia branches per plant (11.75), monopodia branches per plant (3.88), bolls per plant (23.64) and boll weight (6.13) lint (44.03 g plant-1), seed yield (84.89 g plant-1) and seed cotton yield (128.92 g plant-1).While, the ginning percentage and oil content were significantly higher with V3 (Shakti-2) and V2 (Vikram-5), respectively. The application of potassium @ 160 kg ha-1 produced significantly higher sympodia per plant (11.0), bolls per plant(21.85), boll weight (6.00 g), lint yield (41.21 g plant-1), seed yield (76.79 g plant-1), seed cotton yield (118.00 g plant-1), ginning percentage (37.74%) and oil content (17.91%).
Under field, the concentration of K in dry matter at 60 DAS and stalk at harvest was varied significantly for different varieties and it was recorded higher with variety Vikram-5,while the concentration of NP in dry matter and stalk and NPK seed cotton remained unaffected. The uptake of K by dry matter at 60 DAS and stalk and its total uptake was higher with variety V5 (Mico-162). The concentration of K in dry matter, stalk and seed cotton were recorded higher under the application of potash @ 120 kg ha-1 in value of 1.097, 1.041 and 0.982 per cent, respectively.
The uptake of N (46.95 kg ha-1), P (6.52 kg ha-1) and K (27.73 kg ha-1) by dry matter at 60 days was recorded higher at 120 kg K2O ha-1 . Similarly, the application of potassium @ 120 kg ha-1 registered significantly higher uptake of N, P and K by seed cotton (62.05, 6.63 and 38.74 kg ha-1) and P and K by stalk (8.35 and 25.51 kg ha-1) by seed cotton. Almost, similar trend was observed for total uptake of NPK.
The variety V4 (Rashi-2) recorded significantly higher bolls per plant (37.00) , boll weight (6.38 g) , dry matter yield (2633 kg ha-1), lint yield (906 kg ha-1), seed cotton yield (2626 kg ha-1) and total cotton yield (6419 kg ha-1). Similarly, the higher value of micronair (4.752), stepple length (2.839 cm) and 2.5% span length (2.917) were recorded with variety V4 (Rashi-2). Fertilization of potassium @ 120 kg ha-1 gave significantly higher dry matter (2534 kg ha-1), lint yield (908 kg ha-1), seed cotton yield (2597 kg ha-1), stalk yield (3728 kg ha-1) and total cotton yield (6325 kg ha-1). Similarly, Quality parameters viz., micronair (4.119), stepple length (2.811 cm), span length (2.879 per cent), oil content (18.12 per cent) and ginning percentage (34.96 per cent) were higher under application of potassium @ 120 kg ha-1.
The availability of NPK in soil at 60 days growth period and at harvest was not influenced significantly by varieties of Bt. cotton. The application of potassium @ 120 kg ha-1 produced significant effect only on availability of potassium in soil at 60 days growth stage and at harvest and it was recorded higher under application of potassium @ 120 kg ha-1.
The Bt. cotton variety Rashi-2 out yielded over rest of the varieties in pot and field experiments. The root parameters and yield and quality attributes were also recorded with higher values in case of the cotton variety Rashi-2. The varieties did not differed significantly with respect to the total concentrations of NPK even though they have significant variations in the root parameters. However, in case of total nutrient uptake the variety Rashi-2 observed maximum NPK, might be because of higher yield, root influx of NPK as influenced by K levels exhibited varietal variations being maximum with Rashi-2 at least during initial (30-60 DAS) and later (80-120) stages. The root influx of NPK remained unaffected by the levels of K during 60-90 DAS.
In the field experiment the crop variety Vikram-5 recorded higher K content at 60 DAS. But tested K uptake was higher with Mico-162. The K uptake followed the trend of K application levels. However, Rashi-2 out performed over rest of the varieties by recording highest yield, yield attributes and quality parameters under 120 kg ha-1 of K application.