TRIPURA
D. Hand weeding Fig 15. Effect of Tembotrione and Tynzer on
weeds in maize field.
Weed management in upland kharif rice
Rice var. Hakuchuk-2 was dry seeded in upland field during kharif 2018. The field was highly infested with sedges, grassy and broad-leaved weeds. The highest grain yield of 4.8 t/ha as recorded in the weed free treatment (weeding was done as and when weed growth was noticed till 60 DAS) was statistically similar to the yields recorded in pre-emergence application of pendimethalin @ 1000 g a.i./ha plus hand weeding at 30 DAS (4.67 t/ha), Pendimethalin
@ 1000 g a.i./ha (PE) with application of bispyribac sodium @ 25 g a.i./ha Post at 25 DAS (4.33 t/ha) and two hand weeding at 20 & 40 DAS (4.47 t/ha). Control (no weeding) yielded the significantly lowest grain yield (0.56 t/ha) among the given treatments. The data showed that in absence of any control measure, weed reduced the upland DSR yield by 88.3%. The growth of rice was fully suppressed by weeds (Fig.
16) in the plots where no weeding was done.
Fig 16. Complete suppression of growth of upland DSR in absence of weed control measure.
National Mission for Sustaining Himalayan Ecosystem (NMSHE-TF 6)
Monitoring of soil organic carbon pool under different land use system in Tripura
Soil Organic Carbon under different pineapple based agro-forestry systems : To assess the effect of major land use systems, SOC in different soil horizons in different agro-forestry systems were monitored e.g., neem - pineapple, teak - pineapple, eucalyptus - pineapple, sisso- pineapple established in 1989 at Cocotilla farm in comparison to adjacent cultivated land. Soil cores were obtained from four depth profiles of 0 - 15 cm, 15 - 30 cm, 30 - 60 cm and 60 - 100 cm and composite soils samples were also obtained from respective depths. Results showed that carbon concentration was higher in the sisso- pineapple based system followed by Teak-pineapple system; whereas cultivated land has the lowest SOC concentration. SOC contents in soils of all the agroforestry systems were significantly higher over adjacent cultivated field. Among the agroforestry systems, sisso-pineapple and teak-pineapple had higher SOC pool (22.1±1.4, 11.6±1.2, 18.0±4.3, 19.9±2.2 and 71.6±5.8 Mg/ha and 21.8±2.6, 12.2±1.2, 16.4±2.3, 19.4±0.8 and 69.8±1.6 Mg/ha at 0-15 cm, 15-30 cm, 30-60 cm, 60-100 cm and 0-100 cm, respectively), carbon sequestration (615.3 &
551.4 kg/ha/year, respectively) relative to cultivated land (-57.4 kg/ha/year) in the surface layer.
Soil organic carbon pool and fractions under different planted fodder grasses: Plantation of three fodder grasses like hybrid napier (Pennisetum glaucum × P. purpureum), congosingal (Brachieria rosenesis) and combo napier (Pennisetum purpureum) and natural grasses increased total organic carbon (TOC) pools by 41.5 to 64.4% over the pools in soils under cultivated field (59.5 Mg/ha) over the 15 years.
Soils under natural grasses had higher TOC pool (97.8 Mg/ha) and Walkey and Black carbon (69.6 Mg/ha) pool than those in soils under hybrid napier (84.6 and 61.5 Mg/ha), congosignal (84.8 and 66.3 Mg/ha) and combo napier (84.2 and 64.1 Mg/ha), respectively.
Passive carbon pool in soils under natural grass (46.1 Mg/ha) was significantly higher than those in soil under hybrid napier (39.4 Mg/ha), combo napier (38.2 Mg/ha), congosignal (34.9 Mg/ha) and also in arable land (26.8 Mg/ha). The relative proportions of active carbon pools were higher than that of passive carbon pools across the treatments. In general, all the C fractions were higher in soils under grasses than those in soils under arable crops (Fig. 17).
Fig 17. Effect of different grasses on relative proportion of various fractions of SOC pools Soil organic carbon under mango plantation: The study was undertaken to evaluate the effect of plant canopy of 30 years old mango orchard on horizontal and vertical distribution of SOC. Soil cores were obtained from four depth profiles of 0 - 15 cm, 15 - 30 cm, 30 - 60 cm and 60 - 100 cm and composite soils samples were also obtained from respective systems.
The SOC at 1 m distance from plant base ranged from 5.0 from 7.4 g/kg, whereas, with the increase in distance from plant base, the SOC reduced to 4.4-66 g/kg at 3 m and 3.9-5.3 g/kg at 6 m, irrespective of soil depths. SOC was found to be higher near to plant and as distance from plant base increases, SOC start decreasing (Fig. 18). Soil depth also had an effect on SOC content and it was observed that as depth increases SOC content decreases. At 6 m distance from plant SOC content was measured as 5.3 g/kg, 4.8 g/kg, 4.4 g/kg and 3.9 g/kg for 15 cm, 30 cm, 60 cm and 100 cm, respectively.
Fig 18. Effect of mango plant of horizontal and vertical distribution of SOC
HORTICULTURE FRUITS
Rejuvenation techniques of old unproductive mango trees of cv. Himsagar: Rejuvenation of senile mango trees of cv. Himsagar under Tripura condition should be done during 15th December to 15th January; pruning height from the ground may
vary from 2.5 m to 3.5 m or even some time up to 4.5 m depending upon the trunk height. In the present experiment, pruning height of 2.5 - 3.5 m from the ground level was better along with 2 new shoots/
main branch. Two new shoots were allowed to grow to form tree canopy in the successive years. Better twig length and diameter was recorded (4.3 m and 92.8 cm, respectively) in the 5th year in comparison to pruning height 4.5 m with 4 numbers of new shoots/
main branch. Fruit production started from 4th year and in the 5th year, fruit yield was around 42.5 kg/
tree, fruit weight was 200.5 g and TSS was 18.3%.
Top working of old and unproductive inferior fruit quality mango seedlings : Old and unproductive seedling originated mango trees are to be pruned at 2.5-3.5m height during 15th December -15th January.
Two- three main branches on the tree trunk are dehorned and all other branches on the trunk are removed. Latent buds sprouts on the bark during March-May. Selected healthy new shoots at the upper part of the dehorned branch were top grafted by wedge grafting method in April-May with scions of cultivars viz., Amrapali, Himsagar and Fazli. Scion shoots should be defoliated on the mother tree 7 days before the grafting operation. Grafting success was around 80-85% and only 2 grafted shoots are selected per dehorned branch and 6 grafted shoots/tree. Cultivar Amrapali starts fruiting in the 2nd year after top grafting. However, fruiting on top grafted Himsagar and Fazli starts in 4th -5th year. Top grafted Amrapali fruit weight was around 160.3 g. Fruit yield increased from 9.5 - 12.5 kg/tree to 43.5 - 47.6 kg/tree. Fruit TSS was around 18.4%. In case of Himsagar fruit yield was 40.6 - 44.5 kg/tree in the 5th year with fruit weight (194.3 g) and TSS (18.3%). However, in case of Fazli, fruit yield was 11.4 - 13.3 kg/tree with fruit weight around 350.5 g and TSS (12.8%). Irrigation was applied just after completion of pruning and basin preparation at weekly intervals @ 100 litres/tree and thereafter @ 200-250 litres/tree at weekly interval till 3rd year and then one month interval during winter - spring season. Fertilizer schedule followed : 50Kg FYM + 800g urea + 800g SSP + 400g MOP in the 1st year, 60Kg FYM + 1.0Kg urea + 1Kg SSP + 600g MOP in the second year, 70Kg FYM + 1.5Kg Urea + 1.5Kg SSP + 800g MOP in the 3rd year, 80Kg FYM + 2Kg Urea + 2Kg SSP + 800g MOP in the 4th year and 90Kg FYM + 2.0Kg Urea + 1.8Kg SSP + 1.5Kg MOP.
Application schedule: ½ dose in October-November and rest half in the month of June-July. Regular shoot pruning and thinning was done to regulate the tree canopy. Insects and pests are managed as per the recommended IPM schedule.
Effect of shoot pruning and foliar feeding of nutrients on flowering, fruit set and fruit quality of Litchi under Tripura Condition
On bearing Litchi trees (10-12 years): Shoot pruning and foliar sprays of nutrients: Shoot pruning of 20-30 cm length from the tip of the shoot during 2nd- 3rdweek of June followed by pre-bloom foliar sprays of zinc (0.1%) at one month before panicle emergence + boron (0.5%) at one week before flowering, thereafter, post-bloom foliar sprays of urea (1%) at green fruit stage in first week of April + boron (0.1%) at fruit maturity stage in last week of April has been found to be very much effective for better shoot maturation, flowering, fruiting and higher yield & quality fruits with significantly minimum fruit cracking. However, it is essential to follow the fertilizer schedule of 60 kg FYM, 2.0 kg urea, 1.8 kg SSP and 600g MOP per tree and irrigation at 15 days intervals during fall-winter season and at 7 days intervals during flowering, fruit development and maturity.
All India Coordinated Research Project on Fruits Augmentation and evaluation of germplasm in mango: Survey was done in the major mango growing areas and 12 local mango germplasms were collected and evaluated their physico- chemical parameters.
Soil nutritional status of mango orchards: A total of 13 orchards/ mango growing sites from 3 districts of Tripura were surveyed and further categorized according to the age viz., 0 - 10 years, 10 – 20 years, 20 - 30 years, 30 - 40 years & above. The major soil attributes were in the range: Soil pH (4.10 – 5.70), Soil Organic carbon (0.61– 1.77%), Available N (136.75 – 385.40 kg/ha), Available P (12.94 – 34.95 kg/ha) and Available K (119.88 – 293.71 kg/ha).
Mango diversity fair: A one-day Mango diversity fair and farmer-scientist interaction meet was organized on 20th June, 2018 at ICAR Tripura Centre.
Around 50 types of local and commercial mango varieties were displayed in the exhibition. More than
150 farmers from all the districts attended the fair and also brought mango fruits for display in the fair.
In vitro mass multiplication and conservation of some endangered Citrus species of NEH Region of India’
During the reporting period, surface sterilization of the in-vivo seed explants obtained from freshly harvested fruits of Elaichi lemon collected from orchard identified at Hawaibari, Teliamura, Tripura were standardized. In vivo nodal explants and seeds were used for shoot induction and multiple shoot regeneration studies. The maximum 70 per cent shoot induction were observed from the MS media supplemented with 0.5 mg/L BAP. The maximum length of the proliferated shoots varies from 0.17 cm (1.0 mg/L BAP + 0.5 mg/L Kin) to 0.57 cm (control) at 3 weeks after shoot induction. Shoot tips obtained from in-vitro grown seedlings of Elaichi lemon with various concentrations of BAP alone and in combinations with Gibberellic acid (GA3) after 50 days of inoculation were used for multiple shoot regeneration studies. The maximum number of shoots/explants was recorded from the media supplemented with 0.5 mg/L BAP i.e., 2.58
with highest mean shoot length of 0.82 cm. The combination of BAP (1.0 mg/L) + GA3 (1.0 mg/L) possessed the highest mean number of shoots/
explants (2.85). The maximum shoot length of (1.21 cm) was recorded from the MS media supplemented with 2.0 mg/L BAP in combinations with 1.0 mg/L GA3 at 50 days of subculture.
VEGETABLES
Improvement of cucurbits along with sustainable production technology
Total 35 genotypes of sweet/spine gourd have been collected and evaluated. Genotypes TSG 9, TSG 12, TSG 21, TSG 25, TSG 28 and TSG 29 were superior in yield and quality. The genotype TSG 29 with maximum yield per plant (6.47 kg/plant) considered as a promising line for yield followed by TSG28, whereas TSG35 recorded lowest yield as compared to all the other genotypes. In addition, all total 39 genotypes of Dolichos bean have been colected and evaluated. All have been found superior with high yield and good cooking quality. Passport data of 17 genotypes have been submitted to NBPGR, New Delhi for issuance of IC number.
Table 4. Best accessions for different genetic parameters
S.N. Parameter Range Accessions of best performance