Browsing by Author "Gopi, C S"

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Effect of irrigation and mulching oh the growth and yield of pineapple (Ananas Comosus L.)
(Kerala Agricultural University, 1988) Kuruvilla Varughese; Pillai, G R; Jose Mathew; Santhakumari, G; Gopi, C S
A field experiment was conducted in a sandy loam soil of the Agronomic Research Station, Chalakudy, Kerala for four years from 1981 to 1985 to study the response of irrigation and mulching on tha growth and yield of pineapple. Both irrigation and mulching influenced the fruit yield significantly. The study revealed that irrigating pineapple during summer months at 0.6 IW/CPE ratio (5 cm depth of water) and mulching the crop with dry leaves @6000 kg/ha was optimum. It requires fivato six irrigations during the dry months at an interval of 22 days.
Effect of water management and lime on iron toxicity and yield of paddy
(Kerala Agricultural University, 1996) Durga Devi, K M; Gopi, C S; Santhakumari, G; Prahhakaran, P V
A field experiment was conducted during rabi and summer seasons of 1991-92 in paddy fields of Chalakudy Command Area, in order to study the effect of a single top dressing of lime on iron toxicity and yield of paddy under different water management practices. Considerable reduction in Fe' * concentration could be noticed in soil as well as plant during the period of panicle initiation when lime was applied entirely as one top dressing (at 20 days after transplanting or 30 days after sowing). Application of lime 9 500 kg ha' as single top dressing resulted significantly higher grain and straw yields of paddy as compared to lime >8> 300 kg ha ', 900 kg ha ' and no lime application. The economic level of lime for getting maximum profit from grain and straw was 568 kg ha ' and 635 kg ha1 for the rabi and summer crops respectively.
Foliar diagnosis in coconut (Cocos nucifera, Linn.) in relation to nitrogen, phosphorus and potassium
(Department of soil science and agricultural chemistry, College of Horticulture, Vellanikkara, 1981) Gopi, C S; Jose, A I
A study was undertaken to standardise the foliar diagnostic technique in coconut palm in relation to nitrogen, phosphorus and potassium, making use of the experimental palms of a permanent NPK trial maintained at the Coconut Research Station, Balaramapuram, Trivandrum District. The palms of this experiment received applications of nitrogen, phosphorus and potassium in three levels each viz., 0, 340 and 680 g nitrogen per palm per year, 0, 225 and 450 g P2O5 per palm per year and 0, 450 and 900 g k2O per palm per year. For the standardization of tissue for foliar diagnosis, samples of leaf lamina and mid-rib were drawn separately from all the leaves of the experimental palms. Attempts were also made to establish critical levels of nitrogen, phosphorus and potassium in the leaf and also to work out regression models to predict yield based on the tissue content of these nutrients. Observations revealed that the number of leaves retained by the palm was mainly a function of potassium applied. The number of leaves retained by the palm significantly correlated with the yield(r = 0.93**). The potassium content of lamina of the 2nd leaf can be predicted from the number of leaves retained, making use of the regression equation, Y = 5.32 + 8.95 x where x is the potassium per cent of leaf lamina and Y is the number of leaves retained. The number of leaves retained was also found to be significantly correlated with yield (r = 0.708**). The percentage of nitrogen in the leaf lamina increased with increasing age of leaf till leaf number 6 and thereafter steadily declined. The phosphorus and potassium contents of the leaf were maximum in the youngest leaf and declined with increasing age of leaf. Palms receiving higher levels of nitrogen and potassium retained correspondingly higher contents of nitrogen and potassium in leaf lamina. Application of different levels of phosphorus gave only marginal difference in the percentage of phosphorus in leaf lamina. The nitrogen content of leaf lamina of different leaf position was significantly correlated with yield, the highest coefficient of partial correlation of 0.777** being registered for the 10th leaf, followed by 0.699**for the 2nd leaf. The phosphorus content of leaf lamina failed to establish significant correlation with yield, irrespective of leaf positions. The coefficients of partial correlation between yield and potassium per cent of lamina of leaf positions 2, 3, and 6 were significant, the highest value of 0.663** being recorded for the second leaf. Taking the percentage of nitrogen (N) and potassium (K) in the lamina of 2nd leaf and leaf number (L) as independent variables, yield can be predicted with an accuracy of 84 per cent (R2 = 0.84**) by the regression model, Y = -14.956 + 39.215 N – 16.097 N2 + 83.873 K – 37.388 K2 -11.046 L – 0.202 L2 – 44.186 N x K + 5.529 N x L + 6.276 K x L. The yield can also be predicted with an accuracy of 72 per cent by the regression model, Y = -64.29 + 23.356 N + 1.779 L where N is the nitrogen percentage of lamina of 2nd leaf and L is the number of leaves retained. The critical values for nitrogen and potassium in the leaf lamina of 2nd leaf were found to be 3.31 per cent for nitrogen and 2.17 per cent for potassium. The pattern of distribution for nitrogen, phosphorus and potassium in the leaf mid – ribs was almost similar to the pattern of distribution of those nutrients in the leaf lamina. The coefficients of partial correlation between yield and nitrogen content of leaf mid-rib of leaf positions 6, 14, 15 and 18 were statistically significant, the highest value of 0.677** being recorded for the 14th leaf. The phosphorus content of mid-rib failed to establish significant correlation with yield. The coefficients of partial linear correlation between yield and potassium per cent of mid-ribs were significant for leaf positions 1, 2, 3, 4, 5, 6, 7 and 10, the highest value being recorded for the 4th leaf (r = 0.762**). The multiple correlation coefficient between yield and percentage of nitrogen, phosphorus and potassium was highest (R = 0.771**) for the lamina of the second leaf, among all the position and types of tissue examined and hence, this tissue is recommended as the best tissue for the foliar diagnosis of nitrogen, phosphorus and potassium.
Forms, availability and transformation of potassium in laterite soils as influenced by crop uptake
(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 1998) Nicy Thomas; Gopi, C S
An investigation was taken up to study the fate of applied and native potassium in a laterite soil as influenced by other major nutrients and organic matter and uptake by an annual crop, banana. The experiment was laid out at Banana Research Station, Kannara, Kerala Agricultural University during the period 1996- 1997. The result of the study revealed the necessity of fertilization of the field/soil for better yield. The maximum content and uptake of nutrients N, P and K occurred during the early and late vegetative stages of banana. Hence fertilizers should be applied for the crop from 2 months after planting onwards and continued up to six months after planting. Correlation studies revealed the significant relationship of total K in the soil with yield at different stages. Also poistive correlation between the exchangeable K content in the soil and yield was established. Path coefficient analysis revealed that the direct effect of total K content in the soil on yield was highest at P4 (6 MAP). The indirect effect was maximum at P4 (6 MAP) through P3 (4 MAP). The exchangeable K also was found to have positive direct effect on yield. The indirect effects were not significant. Water soluble K at different stages showed a direct effect of comparable magnitude on yield.
Micronutrient status of soil and leaf of coconut palms growing on reclaimed marshy soil
(Kerala Agricultural University, 1985) Jose, A I; Venugopal, V K; Sushama, P K; Gopi, C S; Saifudeen, N
Standardisation of soil sampling and fertilizer recommendation techniques for coconut gardens
(Department of Soil Sciences and Agricultural Chemistry, College of Horticulture, Vellanikkara, 1998) Nimba Frango, E F; Gopi, C S
An investigation was carried out during 1994-95 to standardise soil sampling technique for coconut and to work out fertilizer recommendation system considering physical/textural nature of soil as well as nutrient levels. Two standing populations of WeT palms grown under good and average management practices (situation A and B respectively) located at Mulamkunnathukavu (Thrissur district) was utilised for the study. From each plot twenty healthy palms were selected for the study. The coconut gardens were separated by a distance of about 1 km and the soil of the site was laterite (Oxisol). Composite soil samples were collected from three depths from the surface and from three radial positions from the bole of the palm. Samples were collected in May, October and January. Leaf samples were collected from the 10th frond and observations on yield and yield attributes were also recorded along with soil samples. Physico-chemical properties of soil, root activity pattern, leaf nutrient content and yield and yield attributes of both situations were compared. Correlation between physical and chemical properties of soil, correlation between soil parameters, leaf nutrient content, yield and yield attributes were also worked out. Both situations showed much variation in physico-chemical properties of soil. Coarser soil fractions were more in situation B while, in situation A finer fractions dominated. High yield situation (situation A) recorded higher values for organic carbon and available K compared with situation B. Depthwise as well as radial distance wise differences were also noticed in the nutrient content. In both situations soil nutrient content decreased as the sampling depth from the surface as well as radial distance from the bole of the palm increased. A perusal of seasonal variation of nutrients in soil indicated that maximum organic carbon, available P and available K content was attained in the second season (in October) which declines continuously through the third and first season except organic carbon of situation B. Comparison of leaf nutrient status of two situations revealed that palms of situation A recorded higher N, P and K content in their leaves. Corresponding differences were also reflected in the production of nuts. Root fractions collected from different depths have indicated that in both situations maximum root activity was confined to a depth of 0-30 cm. Hence conventional method of fertilizer recommendation based on soil testing now practised in the state is not suitable for coconut which takes into account the nutrient status of the top 15 cm layer only. Comparing the radial distance L, established significant relationship only with N while L2 established significant relation with N and K. Since> 75 per cent of the roots are residing inside the basin, sampling from outside the basin alone (L3) is also misleading. Hence mixed composite sampling (L2) including both inside and outside basin soils is more appropriate. Based on the above observations the most suitable sampling technique for coconut is composite sampling containing both inside and outside basin soils from a depth of 0-30 cm from the surface (L2D2). In situation A organic carbon manifested maximum relationship to yield of nuts in the second season and potassium content in the third season whereas organic carbon content of the first season was related with yield in high yield situation. This would suggest that time of sampling is also important which differ between yield group and nutrient to be analysed . . Results also indicated that organic carbon content was related to soil fractions in both situations though, the relationship was in opposite direction. In situation A, finer fractions showed positive and coarser fractions showed negative correlations with organic carbon. The reverse was the case in situation B where coarser fraction had positive and finer fraction had manifested negative relations. It has also been noticed that organic carbon content was linked with nut production in both situations. Varying interaction of organic carbon with different fractions of soil on one side simultaneously with its direct bearing on productivity would point out to the necessity of evolving texture linked indices to get reliable information about nutrient availability status of soil. Therefore, some correction factor should be added to soil test values to account the anomalies caused by the coarser soil fraction which is not having a direct role in production and productivity.