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Probability of Low Temperature Stress at Different Growth Stages for Boro Rice 2007-2008

Md. Shahjahan Kabir
PSO
Agricultural Statistics Division, BRRI-Gazipur

Abstract/ Executive Summary:

The probability of experiencing stage-wise critical temperature approaches to 100% for early established and short duration crop. However, the late established and long duration crop has the probability little less than the early and short duration crop. Irrespective of growth duration, the yield is affected a little of the late established crop. Despite low temperature along with the reproductive phase, the late established crop is quite safe due to the parallel high (day) temperature (31-35⁰C). The high temperature appears to play an important role through the alleviating effect of low temperature. But early-established particularly short duration variety could not escape the low temperature at some of its important growth stages. The low level of high temperature is appeared to drag down the low temperature to aggravate the growth and development of a crop. Therefore, not only the variation of high temperature of the day but also the variation of critical low temperature might have some role in the alleviating effect of cool-injury. The critical low temperature, the high temperature during the low temperature period, periodic return of the critical low temperature with respect to growing region and concerned factors should be a consideration for planning a Boro crop.

Keywords: Probability, Stress, Low temperature

Location: BRRI HQ, Gazipur and Dinajpur Districts.

Start Date: 00-00-1950

End Date: 00-00-2007

Program Area: Socio-economic and Policy

Non-commodity: Analysis and interpretations

Objectives:

The paper discussed the probabilities of critical low temperature and its effect on different growth stages and their pattern of periodic return with respect to few regions of intensive Boro area.

Methodology:

Weekly average of daily minimum temperature data of 33 (1975-2007) years for Gazipur (standard), 57 (1950-2006) years for Dinajpur (Boro-intensive northern cold belt) and Mymensingh (includes boro intensive Kishoreganj haor area) have been used in this study (Data source: BRRI and Bangladesh Meteorological department: BMD). For the simplicity only three regions were considered. Pearson Type I distribution was applied to graduate probability distribution of weekly minimum temperature of each district. A computer program written in SAS language was used to estimate weekly low temperature at different probability (5-95%) levels which were then used to generate probability curves. The probability curves were constructed by using Excel 2000. The Return period or recurrence interval (T) was computed byTwo crop establishment schedules were used, one at 1 November (early established) and another at 30 November (late established). Forty-five-day-old seedlings were considered for the study. The growth stages of the BRRI dhan28 (short duration) and BRRI dhan29 (long duration) were estimated as per Gomosta et al. (2001). The crop establishment of both long and short duration variety was considered at the same time. The critical low temperatures with respect to growth stages were used.

Source of Information: BRRI Annual Report 2007-08

Article Link (Online Journal):

Funding Source:

1. Government

Budget:

Total Budget (Tk.) :

Achievement/Findings:

For long duration BRRI dhan29, these dates are 1 March, 8 March and 22 March. As the short and long duration crops are considered to establish at the same time, they have to experience more or less similar low temperature at the crop establishment. The probability of falling critical low temperature at the crop establishment at Gazipur, Dinajpur and Mymensingh are 74%, 100% and 80%, respectively (Table I and Fig. 3a,b&c). The probability of the onset of low critical temperature is varied from panicle initiation stage and onward. For API, BRRI dhan28 has the probability of 100% for all the regions considered here but for BRRI dhan29 the probabilities vary from 88% at Dinajpur to 100% at Gazipur and Mymensingh. Irrespective of growth duration and regions, the RD and anthesis stage have the probability of 100%. The ripening stage of BRRI dhan29 has less probability of critical low temperature than that of BRRI dhan28. The probabilities at the ripening stage for BRRI dhan29 at Gazipur, Dinajpur and Mymensingh are 15%, 17% and 14%, respectively whereas these values for BRRI dhan28 are 44%, 81% and 60%, respectively.

Knowledge Management: Report/Proceedings