VARIATION IN PLANT GROWTH PARAMETERS AND GRAIN YIELD OF HILL PADDY UNDER MIXED AND MONOCROPPING SYSTEM

Paromita Ghosh

G.B. Pant Institute of Himalayan Environment and Development, Kosi–Katarmal, Almora 263643, Uttaranchal

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INTRODUCTION
Paddy (Oryza sativa) is one of the major crops of the hills. It is traditionally cultivated as a mixed crop under rainfed condition during the “Kharif season” (April – October). The hill natives maintain at least a hundred variety (landraces) of Paddy by cultivating them as a mixed crop (Zhardhari, 2000). But the modern concept of farmers is that field mixtures would reduce product yield and quality. So more and more farmers are switching over to monocropping of Paddy, which is resulting in loss of biodiversity and stability of hill agriculture. Crops have different ability to scavenge nutrients from the soil and divert it into the harvested portion of the crops. Hence either cropping system is expected to have an impact on plant growth parameters, nutrient use efficiency and hence grain yield of individual crops. Limited field scale information on differences in growth response of hill Paddy when planted as a mixed and monocrop prompted me to study the growth response and grain yield of paddy under different cropping system.
MATERIALS AND METHODS
                A field experiment was carried out at the Institute’s experimental site (790 38’ 10’’ E longitude 290 38’ 15’’ N latitude and 1150 m above mean sea level) during the ‘Kharif ’ season. The experiment was laid out in a completely randomized block design with three replicates. The plot size was 1m x 1m with 0.5m interplot and interblock space. There were three treatments namely T1 = Paddy (local variety, control), T2 = Paddy + Foxtail millet (Setaria italica) and T3 = Paddy + Foxtail millet + Barnyard millet (Echinochloa frumentaceae). Local cultivation method was mimicked. Farmyard manure was applied to the plots at a rate of 1000 kg ha-1. The seeds of all the three crops were broadcasted on the same day in their respective plots at a rate of 200 kg seed ha-1. The soil was mixed with the help of a shovel and water was sprinkled on the plots. Seeds of all the three crops (Paddy, Foxtailmillet and Barnyardmillet) germinated within 7 - 12 days. Observations were recorded on plant height, tillers / plant, total biomass (shoot + root) at an interval of 20 days from the date of sowing at six dates. Grain yield was recorded at harvest. All data were analysed for statistical significance according to Snedecor and Cochran, (1989).
RESULTS AND DISCUSSION

Tiller number per plant, shoot height, shoot dry weight and root dry weight are examined across the cropping season. Tillering pattern is a dynamic process and deciding factor for production of spike bearing tillers. It is an important trait associated with the productivity of cereal crops e.g. Paddy. Significant differences in tiller number were observed due to differences in crop combinations (Table 1). The tiller number reduced due to stress in mixed cropping. The tiller number reduced by 15.76% when Foxtail millet was grown with Paddy and it recorded a reduction of 17.64 % when Barnyard millet was grown with Paddy and Foxtail millet.

Differences in shoot biomass are significant. Shoot dry weight reduced by11.05% in treatment 2 and 40.09 % in treatment 3. Average shoot height also fluctuated due to mixed cropping. The relationship between tiller number, root dry weight and shoot dry weight are examined. The relationships is positive and significant between tiller number and shoot biomass and root biomass  (0.69 and 0.88 being the ‘r’ values under control, 0.72 and 0.80 under treatment 1, 0.45 and 0.75 under treatment 2 respectively, n = 18). Kawashima (1968) and Cheema et al. (1979) also reported positive correlation between tiller number and root biomass.

 

Table 1. Cropping season averages of plant growth parameters and grain yield of Paddy under different cropping system (pooled mean value ± 1 SE , n = 18 and 3 respectively).

Treatment

Tillers hill -1

Shoot height

(cm)

Shoot biomass

(g hill –1)

Root biomass

 (g hill –1)

Grain yield

(kg ha –1)

P

8.50 ± 1.38

56.68 ± 8.93

6.51 ± 2.31

1.28 ± 0.06

1765.00 ± 30.77

P + F

7.16 ± 1.31

65.16 ± 14.47

5.79 ± 1.75

0.83 ± 0.18

1542.00 ± 25.19

P + F + B

7.00 ± 1.21

51.26 ± 8.01

3.90 ± 1.43

0.73 ± 0.16

1055.00 ± 23.74

df

17

17

17

17

 

F – ratio

11.21

0.42

13.18

5.84

 

P< 0.005

0.000

0.665

0.000

0.005

 

P = Paddy (control).

P + F = Paddy + Foxtail millet (treatment 1).

P + F + B = Paddy + Foxtail millet + Barnyard millet (treatment 2).

 

             Root biomass under control and treatments is also examined. The maximum root biomass is recorded under control (monocropping system). The relation between root biomass and shoot biomass is positive and the correlation coefficient highly significant, (r-values 0.87, 0.78 and 0.59 in control, treatment1 and treatment 2 respectively, n = 18).

The grain yield and plant biomass is reduced considerably when cultivated with millets compared to the pure stand of Paddy (Table 1). Such reduction is due to decrease in plant stand compared to that of sole cropping of Paddy. Similar results were obtained in grain yield of Finger millet by Siddeswaran et al. (1989). However the combined grain yield of Paddy and millets (treatment 1)  (2323.40 kg ha-1) is much higher when compared with sole cropping of Paddy. Paddy + Foxtail millet (treatment 2) combination recorded the second highest productivity (2312.66 kg ha-1).

Drought stress is an important factor affecting the productivity of rainfed upland rice grown in nearly 6 million ha of land in India, on the other hand millets are known to be drought resistant. Early cessation of rainfall and limited availability of soil moisture due to its loss through surface runoff and poor water holding of soils lead to terminal stress and result in fewer grain number and poor grainfilling (Krupp et al., 1972). Similarly root system and its development are strongly influenced by soil edaphic factors (Mambani et al., 1990; Sharma et al., 1994). Temperature and concentration of reserve food affects growth rate. The extent to which internal and external factors influence the growth rate differs between species and reflects adaptation processes (Hsiao et al., 1976). The variations in plant growth parameters and grain yield are usually attributed to competition for resources such as light water and nutrients by different species. Complementarity in resource use between mixed crop components can limit competition between them and can lead to higher yields per unit land (Willey, 1990; Liebman 1995). Similar results are obtained in the present study also.

Thus it may be concluded that mixed cropping of Paddy and Millets is a better practice for net higher productivity coupled with more net return and greater risk coverage under rainfed condition in midhills of Himalayas.

 

Acknowledgements
I thank Dr. P. P. Dhyani, Scientist Incharge, INHI Core and The Director, G. B. Pant Institute of Himalayan Environment and Development, Kosi–Katarmal, Almora, for encouraging me and providing me the necessary facilities.
References

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Hsiao, T. C., Fereres, E., Acevedo, E. and Henderson, D. W. (1976) Water stress and dynamics of growth and yield of crop plants. In: Water and plant life, (Eds: Lange, O. L., Kappen, L. and Schulze, E. D.) Ecological studies Vol. 19. Springer, Berlin Heidelberg New York.

Kawashima, C. (1968) Root system formation in rice plant. Japanese Journal of Crop Science 57: 26 – 36.

Krupp, M. K., Abilay, W. P. and Alvarez, E. I. (1972) Some water stress effects on rice. In: Rice Breeding, IRRI, Los Banos, Philippines, pp. 663 – 675.

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Mambani, B., De Datta, S. K. and Redulla, C. A. (1990) Soil physical behaviour and crop responses to tillage in lowland rice soils of varying clay content. Plant and Soil 126: 227 – 235.

Sharma, P. K., Pantuwan, G., Ingram, K. T. and De Datta, S. K. (1994) Rainfed lowland rice roots: soil and hydrological effects. In: Rice Roots: Nutrients and Water Use. International Rice Research Institute, Los Banos, Philippines, pp. 55 – 66.

Siddeswaran, K., Ramasamy, C. and Morachan, Y. B. (1989) Nutrient uptake of fingermillet as influenced by intercrops, border crops and N fertilization. Madras Agricultural Journal 76: 361 – 365.

Snedecor, G. W. and Cochran, W.   G. (1989) Statistical Methods.  State University Press, Ames Iowa 50010.

Willey, R. W. (1990) Resource use in intercropping systems. Agriculture and Water Management 17: 215 – 231.

Zhardhari, V. (2000) ‘ Barah Anaaj’ – Twelve food grains: Traditional Mixed farming system. LEISA INDIA. September 2000.

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