Weather Report
The Meteorological data of Sikkim Centre for the year 2009- 2010 is presented in Table 1. The total annual rainfall was 2652.36 mm. The highest rainfall 462.52mm was recorded in July. There was no rain in January. The highest maximum temperature 28 ºC was recorded in June while lowest minimum temperature 7 ºC was in January.
HORTICULTURE Polyembryony in citrus
Polyembryony was studied in Rough Lemon (Fig 1).The degree of polyembryony in mandarin and Rough lemon was 65.30 and 62.80 %, respectively.
The per cent occurrence of one seedling/seed was 48.76 and 50.24, respectively. The degree of polyembryony increased with the increase in the occurrence of two or more number of seedlings.
The mean ratio of one seedling/seed and multiple seedlings/seed was recorded to be 0.93:1. The ratio
increased with the decrease in the degree of polyembryony.
Physico-chemical and sensorial attributes of Sikkim Mandarin
The fruits of East and North districts were bigger and heavier and had more number of seeds/fruit, while fruit of South district was smaller and had less number of seeds. Thin peel, more fruit firmness
and the maximum juice percentage were recorded under North district. The maximum TSS (12.0 ºBrix), reducing sugar (6.20%) and total sugar (9.49%) were recorded in the fruits of East district while that of West district had maximum peel thickness (3.86mm), poor firmness (4.5 lb/sq.inch), minimum acidity (1.34%) and maximum TSS/acid (7.98) and sugar/acid ratio (5.63). The fruits of South district were highly acidic and had minimum TSS/acid ratio (4.71) and sugar/acid ratio (3.05). The fruits of West and East districts had more scores for sensorial attributes in respect of flavour, sweetness and overall impression of juice. Fruits from South district had poor sensorial attributes due to more sourness and less sweetness.
Prevalence of Citrus Tristeza Virus (CTV) in mandarin
The prevalence of CTV virus in mandarin was studied by DAS-ELISA using polyclonal antibody.
The major mandarin growing belts of Sikkim were Table 1. Meteorological data of Sikkim Centre for the year 2009- 2010
Month Temperature Relative Humidity Rainfall Evaporation Sunshine
(mm) (mm) (hr)
Max Min Max Min
Apr 25.8 15.4 84.8 49.3 233.5 3.6 2.9
May 26.2 16.5 86.4 53.0 325.9 4.0 4.3
Jun 28.0 19.4 88.6 63.0 454.64 3.8 2.3
Jul 27.0 20.5 89.0 70.0 462.52 3.5 2.0
Aug 26.8 19.6 90.0 70.7 409.8 3.2 2.2
Sep 27.6 19.2 87.0 60.5 212.9 4.0 3.9
Oct 25.5 16.1 87.6 51.6 229.0 3.3 5.5
Nov 20.6 15.9 85.9 50.5 2.2 1.9 3.6
Dec 17.0 13.0 88.0 52.0 04.8 1.0 0.0
Jan 17.0 7.0 82.0 41.0 0.0 2.0 3.0
Feb 19.0 9.0 81.0 39.0 16.3 2.0 3.0
Mar 23.0 14.0 82.0 48.0 300.8 2.0 2.0
Total 283.5 185.6 1032.3 648.6 2652.36 34.3 34.7
Average 23.6 15.5 86.0 54.0 2.86 2.89
Fig 1. Polyembryony in citrus
infected with CTV. The CTV incidence in North, South and West districts was more than 70%. The incidence was lower in East district. The high incidence of CTV in mandarin without showing characteristics symptoms indicates the presence of mild strain of CTV virus. About 50% of plants were moderately infected and more than 1/3rd of plants were severely infected with CTV. In North district, more than 80% plants were either moderately or severely infected while in South district, plants were mainly moderately CTV infected. In East district the intensity of mildly infected plants was more (30%), while the intensity of severely CTV infected plants was less (20%). The maximum per cent of severely CTV infected plant (70%) and the minimum per cent of mildly infected plants were recorded in West district.
Strawberry
Chandler and Ofra were found to be the best performing varieties of strawberry with the fruit yield of 800g/plant and 750g/plant, respectively. Planting during September gave maximum yield (780g/ plant) with higher TSS/Acid ratio. Etna and Belruby produced maximum number of suckers, 20 and 18, respectively under open conditions. TSS/Acid ratio of the fruits grown under polyhouse was better than the open conditions. Mulching with Sacharum spp.
gave 70% marketable yield followed by tree leaves and paddy straw. Plant mortality was recorded maximum under black polythene mulching followed by paddy straw. Protocol for strawberry jam has been standardized
Chilli
Germplasm evaluation
Germplasm were evaluated for plant growth habit, leaf and fruit character, yield, quality and disease severity. Maximum fruit yield/plant was recorded in Collection-6 (1270 g/plant) at the spacing of 1x1 m. Three collections of cherry pepper were observed for upright fruiting and 12 collections for downward fruiting character. Expected return/ha was calculated at the market price of Rs. 100/kg and it was found that cherry pepper cultivation can give a return of more than Rs. 10.0 lakhs / year Mulching in cherry pepper
To standardize mulching material black polythene, white polythene, forest leaf and Schima wallichi leaf mulch were used. Plant wilting was recorded minimum (21%) in Schima wallichi mulched plants followed by forest leaf mulch and black polythene in cherry pepper. Maximum plant mortality (75%) was recorded in control plots. Chilli pepper showed very less wilting (11%) in Schima wallichi mulching.
Shelf life of cherry pepper
Cherry pepper was stored under room temperature and at 40C temperature for evaluation of storage life. Maximum shelf life of 21 days was recorded at 4°C, whereas chilli could be stored only for 6 days under room temperature (Fig 3).
Fig 3. Cherry peppers
Sprinkler irrigation in vegetables
Sprinkler irrigation is being proved to very feasible and an important techniques to increase water use efficiency during lean period (November -
Fig 2. CTV incidence in Sikkim
February). Through this method about 50% less water is required than that of channel irrigation.
Moreover the yield of vegetable was also increased by 15%. The frequency of irrigation was twice in a week and each irrigation has the water application rate at 4 l/m2.
ENTOMOLOGY
Eco- friendly management of insect pests in rice
Stem borer, leaf folder, whorl maggot and gundhi bug were found as important pests of rice in Sikkim.
Stem borer and leaf folder population was found maximum during August-September. The whorl maggot caused maximum damage in the second fortnight of July. Gundhi bug population was found maximum when the crop attained the milking stage (first fortnight of October). Species composition of rice stem borer was monitored. Although all the five species of stem borer were observed but yellow stem borer, Scirpophaga incertulas was found dominant followed by striped borer, Chilo suppressalis. Spiders, Apanteles, dragon flies and Coccinellid beetle are some potential natural enemies in rice ecosystem of Sikkim.
Out of fifty rice entries screened against pests, twelve (Bachi, Basmati Attey, RCRT-FG, RC Mani- 6, RCPL-1-126, Surkey Marsie, Ramzira, Kalami, Dhoot-kati, Lungnilaphaw, RC Maniphaw-4, and Tulasi) were found promising.
Bio- rational management of insect pests in Sikkim Mandarin
Leaf miner, lemon butterfly, leaf roller, looper caterpillar, aphids (Fig.4), whitefly, Spodoptera, scale insect, mealy bug and semi looper were important pests in citrus nursery. In the main field the incidence of trunk borer, bark eating caterpillar and shoot borer are common. The orchards of all the surveyed areas were infested (26-35%) with fruit fly. The adults and grubs of lady bird beetle, Menochilus sexmaculata and Coccinella septempunctata were observed as potential predators in all the surveyed orchards.
Bacillus thuringiencis (Delfin 3G) was found most effective to control lemon butterfly while Agrospray (Servo) was found effective against aphids and leaf miner in Sikkim Mandarin orchard.
Five different traps were evaluated against fruit fly in citrus orchard. Amongst them Methyl eugenol + Ethanol + Malathion (4:5:1) showed promising result by trapping 40.54 adults/week
Bio-rational management of insect pests of major spices
A new but potential pest has been recorded in chilli. Tea mosquito bug, Helopeltis theivora is a major pest of tea in Assam and West Bengal. In Sikkim, the infestation of Helopeltis (Fig 5) was recorded for the first time in chilli. Both nymphs and adults suck the sap of the leaves and shoots and produce numerous sunken brown spots. One fully matured nymph can produce more than 100 spots.
Nimbicidine @ 3 ml/l was found effective against shoot borer, leaf roller and grasshopper of ginger
Fig 4. Infestation of citrus aphid Fig 5. Infestation of nymphs of H. theivora
followed by Neemazal @ 3 ml/l. Entomopathogenic fungi (Metarhizium and Beauveria) were found effective against white grub. Servo Agro-spray 6 ml/l was found effective to control aphids and white flies in chilli and Bacillus thuringiencis (Delfin 3G) 2g/l was found effective against cutworm. Neem formulations like Nimbicidine and Neemazal @ 3 ml/l and Delfin 3G 2 ml/l were found effective against leaf eating caterpillar. From the survey it was observed that the adults and grubs of lady bird beetle, Menochilus sexmaculata and Coccinella septempunctata were observed as potential predator (Fig 6).
SOIL SCIENCE
Integrated nutrient management in maize An experiment was undertaken on organic nutrition of maize during the main season of March 2009 with var. Vivek Sankul Makka-11. Dolomite was applied for soil acidity management @ 2 t ha-1. Mixed compost, neem cake, azophos seed treatment and vermicompost were applied as sole or in different combinations as sources of nutrition. The yields of the crop ranged from 1,600 to 4,450 kg ha-1.
Studies were conducted on soybean-mustard rotation during 2009-10 with integrated nutrient management in the main crop and evaluating the effect of residual nutrients on mustard with one irrigation. 10 treatment combinations of chemical fertilizers as starter dose, mixed compost, neem cake and dolomite in nine combinations and one without
nitrogen (control) were applied on soybean var. PK- 1024 during kharif 2009. N:P:K @ 30:40:30 was applied alone and in conjunction with neem cake and dolomite @ 2 t ha-1. Yield obtained with neem cake 1 t ha-1 + mixed compost 2.5 t ha-1 + dolomite (3,240 kg ha-1) was statistically at par with integrated nutrient management through urea +SSP+MOP @ 30:40:30 + dolomite @ 2 t ha-1 + neem cake @ 0.5 t ha-1 (3,135 kg ha-1).
Short duration, high yielding mustard variety M- 27 was sown in November 2009 in the same soybean plots under integrated nutrient management and was irrigated once at the flowering stage. Conjunctive application of urea + SSP + MOP @ 30:30:30 + dolomite @ 2 t ha-1 + Neem cake @ 0.5 t ha- produced the highest grain yield (8.12 q ha-1) and the treatment of neem cake 1 t ha-1 + mixed compost 2.5 t ha-1 + dolomite produced yield of (7.11 q ha-1) on the residual soil nutrients.
INM in Rice
Studies were conducted in kharif with three improved rice varieties VL Dhan-61, Pusa Sugandh II, Pant Dhan-10 and one local check “Attey” under two organic sources of nutrition mixed compost and neem cake to evaluate their performance in terms of yield, yield attributes and N-use efficiency in comparison with 3-split urea application. 25 day- old seedlings were transplanted with 20 x 15 cm spacing between rows and hills, 2 seedlings were placed at each hill in plots of 10m2. The performance of three improved varieties - Pant Dhan-10, VL Dhan-61 and Pusa Sugandh-II and one local cultivar
‘Attey’ under organic nutrition and conventional system was continued. The rice grain yields ranged from 2.32 to 3.84 t ha-1 with mixed compost; 2.25 to 4.43 t ha-1 with mixed compost and neem cake as compared with 2.12 to 4.04 t ha-1 rice grain yield with 3-split urea application. The no fertilizer (control) yield ranged from 1.20 to 1.64 t ha-1. Organic nutrition in buck wheat
Studies were undertaken on organic nutrition of buckwheat with local cultivar “Mithe”. The crop was sown in two spacing of 20 x 20 and 30 x 30 cm in four replications on which six treatments were imposed. Five treatment combinations of mixed compost, neem cake and seed treatment with azophos along with control were basally applied at
Fig 6.Grub of lady bird beetle predating on aphid in chilli
sowing. Observations on yield and yield attributes and soils were recorded. The highest grain yield of buckwheat was recorded with organic nutrition management through mixed compost 5 t ha-1 + neem cake 0.5 t ha-1 was 1550 kg ha-1.
Studies were conducted on organic nutrition of mustard during November 2009 with var. M-27. The highest yield (1,140 kg ha-1) was recorded with the treatment mixed compost @ 5 t ha-1 + vermicompost
@ 1 t ha-1 + neem cake @ 1 t ha-1 + dolomite @ 1 t ha-1 which was followed by mixed compost @ 5 t ha-1 + vermicompost @ 1 t + dolomite @ 1 t ha-
1 that produced (915 kg ha-1).
ANIMAL NUTRITION
In vitro fermentation study was conducted in seven tree fodder, three jungle grasses and one root sample. Fresh cow dung buffered and fortified with minerals was used as inoculums. Results showed a wide variability in gas production among samples at different time intervals (Table 1 & 2). After 96 hours of incubation, the volume of total gas and carbon dioxide ranged between 66.8 to 234.7 and 18 to 157 cc per mg of samples on dry matter basis.
The value for methane production in the present study was 37.2 to 78.4 % of the total gas produced.
The observed inoculums pH varied from 8.21 to 8.51 was significant (P<0.01) however, apparently could not affect the fermentation pattern.
Total gas production in various samples increased and differs significantly after 12, 24 and 96 hours of incubation period. The lowest methane production was observed in Tapioca root (37.23%) followed by tree fodder Ficus bengalensis (38.74%).
Tapioca root is low in crude fiber which is directly correlated with the lowest methane production in the present study. The proportion of methane with respect to its ability to produce total fermentable gas when incubated with fresh faces was highest in Utis followed by Dallopate, Udasey and Elamy.
The chemical composition of fodder samples could not be correlated with production of total gas and methane in the present study. However, an increasing trend of methane production in fodders containing low ether extract content could be noted.
On the basis of present study it was concluded that the level of crude fibre and ether extract content of the fodder plant may play anti-methanogenic role and change the fermentation pattern.
LIVESTOCK PRODUCTION AND MANAGEMENT
Reproductive disorder of bovine in Sikkim During the reported period of study, the survey was made for reproductive disorder of bovines in all the four districts of Sikkim. A total of 1,270 cases were recorded and analyzed. Anoestrus was the major problems (24.41%) followed by delayed
Table 1. Total gas, carbon-dioxide and methane production (cc/g DM) and methane roportion (%) of total gas after 96 hours of incubation with fresh faecal inoculum
Common name Botanical name Total gas Volume of Volume of Methane
volume/g CO2 /g methane/g (%)
Bardar Ficus bengalensis 161.6b 99.5b 62.0ab 38.7a
Bilaunae Maesa chisia 103.6ab 45.0a 58.6ab 58.5ab
Dallopate - 74.7 a 28.0 a 46.7a 64.3bc
Jhimani Eurva japonica 127.6ab 62.2ab 65.4ab 51.7ab
Khasre Ficus hirata 125.8ab 58.0ab 67.8ab 59.4ab
Khankappa Evoidia frarinifolia 122.6ab 54.9ab 67.6ab 56.4ab
Utis - 66.8a 18.1a 48.7a 78.4c
Arupate leaves Collocasia 96.8 a 53.6ab 43.2a 43.3ab
Elamey Ageratum conyzoides 75.4 a 29.0a 46.4a 63.0bc
Udasey - 80.9 a 31.0a 49.9a 61.7bc
Ful tarul Manihot esculenta 234.7c 156.6c 78.8b 37.2a