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Wednesday, 30 October 2013

FYT-99/G4, an early sprouting Morus alba genotype for north western India

R.K.Pandey
Regional Sericultural Research Station, Miransahib, Jammu 181101
[Previous stories written by RK. Pandey can be accessed HERE and HERE]
Abstract
Fig.1 Stages of bud break after winter dormancy
In north western sub Himalayan states such as Jammu and Kashmir, Punjab, and Himachal Pradesh, early sprouting mulberry genotype is a boon for on time spring crop rearing because any delay in bivoltine rearing in spring season adversely affects cocoon production. Among the five newly evolved genotypes, FYT-99/G4 was found to be an early sprouter.  FYT-99/G4 sprouted first of all after 33 days of winter pruning. Secondly, Vishala sprouted 44 days after pruning. The genotypes, S-1635 and C-2038 sprouted together after 49 days. Suvarna-2 sprouted lastly 52 days after winter pruning. The differences were significant except between C-2038 and S1635.  However, the differences in sprouting duration were not significant after July pruning in monsoon season, where, FYT-99/G4 sprouted within 11days of pruning, Vishala and S-1635 sprouted within 12 days. The genotype C-2038 sprouted within 14 days after pruning and Suvarna-2 sprouted within 15 days in Monsoon period.
In spring season, which is the main period for bivoltine silkworm rearing in North western Indian states, due to the early sprouting character, FYT-99/G4 is useful for feeding silkworms at Chawki Rearing Centres to synchronize adult age rearing with leaf maturity in the field on already existing mulberry trees, which usually sprout late. By on time distribution of chawki silkworms, the cocoon yield in the field improves considerably.
Introduction
With the onset of spring season with long photoperiodic conditions, the mulberry, which sprouts first of all, is called early sprouting variety. Such early sprouter is identified as early sprouting genotype.  Early sprouters are preferred for feeding silkworms in the spring season, because they give sufficient quantity of leaves on time in March. With rise in temperature in April, the season becomes unfavorable for silkworm rearing. So far, only the Morus alba genotype ,S146 and S1635 are available for the north western sub Himalayan, which sprout first of all in January itself as a result, there is great demand of these by the farmers of the region, because other genotypes sprout in the first week of March. Koul (2006) examined twenty varieties of mulberry in Jammu and   demarcated two groups. One, early sprouting tropical varieties, Chak Majra, Tr-10, Sujanpur and C763. The second group includes late sprouting temperate varieties, Ichinose, Rokokayoso, Enshutaka and Goshoerami.  While tropical varieties sprouted in 3rd week of January in Jammu region, the temperate varieties sprouted in the first week of April under the sub tropical environment of Jammu.

In the present work, the sprouting behavior of five newly developed genotypes of the Sericultural Research Institutes of South and North East were observed from early sprouting point of view as per the need of north western Sub tropical India.
Material & Methods
The experiment was conducted at the Regional Sericultural Research Station, Miransahib, Jammu.  The area is sub –tropical, situated on the geographical coordinates of 31o14’29” N, 77o2’12”E. It has an average elevation of 327m (1073ft) above mean sea level. The soil of the site is sandy loam in texture, neutral to acidic in reaction (6.5). The genotypes were imported from different Research Institutes under an All India Coordinated Experimental Mulberry trial ( TableI)
Table I : Genotypes evaluated at Jammu
Preparation of saplings
The hard wood stem cuttings of all the genotypes were prepared choosing the middle part of the juvenile twigs. Each cutting measured about 2.5 cm in diameter and 15cm in length possessing 3-4 active vegetative buds. Due care was taken to avoid damages to the buds and cut ends while preparing the cuttings. The cuttings were planted in the freshly prepared nursery containing well dried pulverized garden soil,sand and well decomposed farm yard manure in the proportion 1:1:1 and maintained with consistent care in July( Jolly and Dandin,1986).
Raising of plantation 
Six months old saplings were planted in the pits under 90x90 cm (plant to plant) in random block design with six replications.
Block size (Length x Breadth) :  40.5m x 8.1m =325.05 sq .m.
Net Experimental area /plot :  6.3m x 6.3 m=39.69 sq.m.
Total experimental area /plot : 8.1m x 8.1m=65.61 sq.m.
No. of experimental plants /plot: 7x7= 49
Total number of plants /plot: 81
Pruning
The saplings were pruned at bottom  level  nearly 15 cm from the ground ,immediately after sprouting of the newly planted saplings to make bush type canopy. Subsequently, a pruning schedule was followed. where annually middle pruning was done 100 cm from ground  in  mid December (winter) and 30 cm from ground in July(Monsoon). Annually Farm yard manure was applied @20MT/ha in two split doses. NPK was applied @75:75:75 kg/ha in two split doses, besides routine cultural operations.
Fig.2. Sprouted mulberry,Morus alba, Genotype FYT-99/G4

Data collection 
Data on sprouting behavior of different genotypes was recorded after one year of plantation by adopting methods of analysis of variance appropriate to the design of the experiment (Sundaraj et.al.1972).    
Results and Discussion
The early sprouting Genotype
It can be seen from Table II, that among the five newly evolved genotypes, FYT-99/G4 was an early sprouter.  FYT-99/G4 sprouted first of all in January after 33 days of winter pruning on December, 17. Secondly, Vishala sprouted 44 days after pruning. The genotypes, S-1635 and C-2038 sprouted together after 49 days. Suvarna-2 sprouted lastly 52 days after winter pruning. The differences were significant except between C-2038 and S1635.
The differences in sprouting duration were not significant in monsoon period after July pruning (Table II). In monsoon season, FYT-99/G4 sprouted within 11 days after pruning, whereas Vishala and S-1635 sprouted after 12 days. The genotype C-2038 sprouted 14 days after pruning and Suvarna-2 sprouted lastly after 15 days.
Table II: Asynchronous sprouting of the mulberry genotypes 
At the Regional Sericultural Research Station, Miransahib, Jammu, number of accessions are maintained under germplasm including the varieties that were reported by Koul (2006) as early sprouter, such as Chak Majra, Tr-10, Sujanpur and C763.  Chak Majra is synonym of the variety S146, which is widely cultivated in North West sub Himalayan India due to early sprouting nature. Among the five new genotypes evaluated in the present work, it was observed that FYT-99/G4, S1635 C-2038 sprouted   earlier than the ruling variety S146, after winter dormancy.
Effect of Rainfall and Temperature
Soil moisture plays an important role in leaf bud break after winter dormancy. During the present investigation, at the time of winter pruning in December, 69.2 mm rainfall occurred.  Thereafter, 41.4mm, 168.2mm and 34.8 mm rainfall occurred in January, February and March, respectively.  To survive the coldest part of the winter, mulberry buds are isolated from the mulberry’s vascular system (water-conducting xylem and nutrient-conducting phloem) and start losing moisture from autumn season with decline in ambient relative humidity.  It needs both increasing temperature and tissue wetting for bud break and shoot emergence to occur with onset of spring season.  The results of this study reveal that the varieties differ in their requirement of moisture and temperature for leaf sprouting and growth.
The average maximum temperature declined upto19.2oC in December from 25.8oC of November. Similarly, the average minimum temperature declined upto 5.8oC in December from 9.4oC in November. Winter continued in January with similar low temperature. The temperature started rising in February, when the average maximum temperature was 19.2oc and minimum 9.1oC. Accordingly, the early sprouting genotypes such as FYT-99/G4, showed bud break in February with rise in temperature, whereas other varieties took a few more days.
Effect of Photoperiod
Photoperiod exerts a considerable influence in the leaf bud break of mulberry. An optimum period of 11 hours illumination is desirable. The day length was observed to increase from February in Jammu, which coincides with leaf bud break in early sprouting genotypes of mulberry. The important role of short photoperiods in the autumn as the dormancy-inducing signal has been amply demonstrated and documented in a wide range of woody plants (Kramer, 1936; Downs and Borthwick, 1956).The results show that photoperiod requirement of different varieties may differ as a result, the genotype such as FYT-99/G4, might have required less duration of light to sprout in comparison with other genotypes.
The early sprouting genotype such as, FYT-99/G4, S1635, and S146 are useful for feeding chawki silkworms at Chawki Rearing Centres to synchronize adult age rearing with leaf maturity in the field on already existing mulberry trees, which usually sprout late. By on time distribution of chawki silkworms, the cocoon yield in the field improves considerably.
References
Downs R.J and Borthwick H.A. (1956) Effect of photoperiod on growth of trees.  Botanical Gazette. , 117:310–326.
Jolly, M.S. and Dandin, S.B.(1986)  Collection, conservation and evaluation of mulberry(Morus spp.) germplasm..CSR&TI, Mysore, India, 43.
Koul. A.(2006) Mulberry leaf sprouting as an indicator of spring rearing.  Journal of Research,SKUAST - J, 5, 2, 173-178.
Kramer, P.J. (1936) Effects of variation in length of day on growth and dormancy of trees. Plant Physiology, 11:127–137.
Sundaraj,G.L.,Nagaraju,M.N.,Venkataramu and Jaganath (1972) Design and analysis of field experiments.UAS,Misc,Series No.22,Bangalore,India,424-440.

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