Madras Agric. J. 92 (4-6) : 328-330 April-June 2005 Research Notes

Sett selection and treatment for higher productivity of rainfed Cassava R. JEGATHAMBAL AND K. SHANMUGAM Tapioca and Castor Research Station, Yethapur Cassava (Manihot esculenta crantz), popularly known as tapioca, is a native of Brazil in Latin America and was introduced to India(Kerala) by the Portuguese in the 17th century. Among the different tropical root and tuber crops grown in India, cassava is of significance since it can produce more calories per unit area per unit time. Its importance in tropical agriculture is due to its drought tolerance, wide flexibility to adverse soil, nutrient and management conditions including time of harvest. (Mohankumar et al, 2000). In India, cassava is mainly cultivated in the four sourthern states viz., Kerala, Tamil Nadu, Andhra Pradesh and Karnataka. Its productivity has increased from 20.6 t/ha to 24.5 t/ha during 1997 (FAO, 1997). In a vegetatively propagated crop, great care and vigilance are needed in the selection and propagation of seed material to obtain proper germination and field stand. To overcome the problem of demand for disease-free, healthy propagating material, comparative study on setts with single bud, double buds and triple buds is needed. Sett treatment with biofertilizers like Azospirillum and phosphobacteria is recommended for cassava. Similarly, to alleviate the Zn and Fe deficiency, foliar application of 0.5% ZnSo4, 1% FeSo4 and 2% urea is recommended for cassava. However, the effect of sett treatment with biofertilizers in combination with micronutrients has not been studied. Hence, this study was taken up with the sett treatments using micronutrients and biofertilizers.

A field experiment was conducted in farmer’s field at Ariapalayam near Tapioca and Castor Research Station, Yethapur for maximising the productivity of cassava Var. Co3 through sett selection and treatment with micronutrients and biofertilizers. The experiment was laid out with 3 mainplot treatments and 4 sub-plot treatments, replicated three times adopting split-plot design. The treatment structure is given below: Main-plot S1 - Sett with single bud S2 - Sett with double buds S3 - Sett with triple buds (farmer’s practice) Sub-plot T1 - Control T2 - Sett treatment with micronutrients Zn & Fe each at 0.5% T3 - Sett treatment with biofertilizers Azospirillum & phosphobacteria each at 3% T4 - Sett treatment with micronutrients + biofertilizers. The setts were soaked first in micronutrients (ZnSo4 and FeSo4 each at 0.5%) for 15 minutes followed by biofertilizers (Azospirillum and phosphobacterium each at 3%) for 15 minutes and then raised in the nursery. After 25-30 days, the seedlings were transplanted in the main field. A uniform dose of 50 kg N, 65 kg P2O 5 and 125 kg K2 O/ha were applied basally to all treatments.

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Sett selection and treatment for higher productivity of rainfed Cassava

Table 1. Sett selection and sett treatment on the productivity of rainfed cassava Characters Mainplot treatment

Sub-plot treatment

CD(p=0.005)

T1

T2

T3

T4

Mean

169.3 172.1 173.0 171.4

169.4 172.2 173.0 171.5

170.1 173.1 173.2 172.1

171.2 173.0 173.5 172.6

170.0 172.6 173.2 --

Main-plot-0.88 Sub-plot- 1.1 3 Interaction- 1.96

Number of S1 tubers/ S2 Plant S3 Mean

5.5 6.2 6.3 6.0

5.7 6.3 6.2 6.1

5.9 6.4 6.5 6.3

5.8 6.4 6.6 6.3

5.7 6.3 6.4 —

Main-plot-0.15 Sub-plot - 0.28 Interaction-0.45

Girth of tuber (cm)

S1 S2 S3 Mean

12.6 13.1 13.9 13.2

12.8 13.2 14.2 13.4

12.9 13.5 14.3 13.6

13.0 13.6 14.5 13.7

12.8 13.3 14.2 —

Main-plot - 0.34 Sub-plot - 0.23 Interaction-0.49

Length of S1 tuber (cm) S2 S3 Mean

17.2 18.0 18.2 17.8

17.5 18.2 18.3 18.0

17.6 18.3 18.5 18.1

17.9 18.5 18.8 18.4

17.6 18.3 18.5 —

Main-plot-0.33 Sub-plot -0.31 Interaction-0.57

Tuber S1 yield S2 (kg/plant) S3 Mean

1.345 1.408 1.415 1.390

1.370 1.415 1.437 1.408

1.389 1.425 1.445 1.420

1.400 1.432 1.458 1.430

1.376 1.420 1.439 —

Main-plot-0.03 Sub-plot -0.01 Interaction-0.02

Plant height (cm)

S1 S2 S3 Mean

The data on growth parameters viz., plant height at harvest, number of tubers / plant, girth of tuber(cm) and length of tuber(cm) and yield of tubers/plant were recorded and analysed statistically. The plant height was more (173.2cm) in setts planted with triple buds (S3) among the main-plot treatments. Among the sub-plot treatments, T4 (sett treatment with micronutrients and bio-fertilizers) recorded highest plant height of 172.6 cm. Sett with triple buds treated with micronutrients and biofertilizers (S3 T4)

resulted in the maximum plant height (173.5cm) than other combinations. As observed in case of plant height, setts planted with triple buds (S3) and treatment with micronutrients and bio-fertilizers (T4) recorded the maximum tuber number of 6.4 and 6.3, respectively. Sett with triple buds treated with micronutrients and bio-fertilizers produced high number of tubers (6.6) The maximum girth of tuber of (14.2 cm) was recorded by the setts planted with triple

R. Jegathambal and K. Shanmugam

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buds (83), while the setts planted with single bud had the minimum girth of tuber (12.8cm). Sett treatment with micronutrients and biofertilizers (T4) recorded significantly the highest tuber girth of 13.7cm.Triple budded setts treated with micronutrients and biofertilizers (83 T4) produced the maximum girth of tuber (14.5 cm).

parameters, sett treatment with micronutrients and biofertilizers(T4) yielded the maximum ( 1.430 kg/plant) while it was (1.390 kg/plant) less in control (Tl). Triple budded setts treated with micronutrients and biofertilizers (83 T4) was found to be the best treatment in producing the highest tuber yield of 1.458 kg/plant.

Setts with triple and double buds produced lengthier tubers. Micronutrients when combined with bio-fertilizers for sett treatment, the tuber length was 18.4 cm. Triple budded setts with the best sett treatment produced the maximum length of tubers(18.8cm).

References

Tuber yield was high when triple budded (1.439 kg/plant) or doubled budded (1.420 kg/ plant) setts were planted. As evident in other

FAO, 1997. FAO production year book 57 : pp.8. Mohankumar, C.R., G.M.Nair, James George, C.S.Ravindran and V.Ravi. (2000). Production technology of tuber crops. CTCRI, Trivandrum. pp.7. Published by the Director, CTCRI, Trivandrum. (Received : November 2003; Revised : September 2005)

Madras Agric. J. 92 (4-6) : 330-334 April-June 2005 Research Notes

Effect of seed desiccation on the seedling characters of mango (Mangifera indica L.) ANILA. P AND GIRIJA. T Department of Plant Breeding and Genectics, College of Horticulture, Vellanikkara, Thrissur, 680056. Commercial propagation of mango is mainly through vegetative means. The rootstock for vegetative propagatin is produced from seeds. In recalcitrant seeds like mango, reduction in the moisture content leads to seed deterioration (Doijode, 1990, Girija et al. 2001). The degenerated seeds germinate slowly (Kearns and Toole, 1939). It has been reported by Berger et al. (1998). that in the mango varieties Espada and Uba, low density seeds showed poor performance with respect to germinability and seedling growth. In mango, large seeds showed better performance then medium and small sized

seed nuts. Farrant et al. (1989) and Islam, et al. (1997) had observed that seed deterioration involves complex changes in many cellular constituents. The accumulation of these changes leads to decreased seed vigour and viability. Unlike in other fruit trees; rootstock standardization based on vigour potential is still an unfinished task in mango. The degenerative processes occurring in seeds and their influence on seedling performance is neglected in the selection of seeds and seedling. This results in wide variation in the performance of grafts from the same clones.