现代农业地理信息系统——良种水稻和水产养殖部分外文翻译资料

 2022-04-26 22:48:35

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Improved rice-aquaculture integration in coastal rice-shrimp system in Bangladesh

M.J. Alam1, M.L. Islam, T.P. Tuong2, and O. Joffre3

1

Bangladesh Fisheries Research Institute, Brackishwater Station, Paikgacha, Khulna 9280, Bangladesh

3

alammj_bfri@yahoo.com

International Rice Research Institute, Los Banos, Philippines

2WorldFish Center, Batu Maung 11960, Bayan Lepas, Penang, Malaysia

Abstract

The rice–shrimp system in the coastal zones of Bangladesh suffers from a high risk of disease

outbreaks in the dry season shrimp (Penaeus monodon), while income from the rainy season rice is

often low due to its low yield. This study aimed at improving productivity of the rainy season farming

by improving rice yield and integrating it with freshwater prawn (Macrobrachium rosenbergii) and

genetically improved farmed tilapia (GIFT). Experiments were carried out to compare the effect of

three different times of stocking of post-larvae (PL) of prawn and five rice varieties on yield of prawn,

GIFT, and rice and on farmersrsquo; net economic return. Prawn yield (72.53plusmn;4.70 kg/ha) in early PL

stocking treatment in June was significantly (Plt;0.05) higher than those of later stocking in July and

August. A 60-day difference in prawn grow-out period resulted in an increase of about 237% in

average individual body weight. PL stocking time did not affect GIFT and rice yield. Rice varieties of

BR 23, BRRIdhan 40, and BRRIdhan 41 significantly outyielded other varieties by 31.83%. Compared

with monoculture of local rice varieties, high yielding rice varieties increased farmers#39; return by Tk.

18,420/ha (US$1=68.5 BDT–October 2008); integration of aquaculture further increased it by Tk.

13,050–38,227/ha. Return from aquaculture increased with advancement of prawn stocking times.

While PL stocked in June resulted in a net return of Tk. 28,143/ha, that in July and August resulted in

Tk. 8,810 and 3,868/ha, respectively. The rice-GIFT-prawn integrated farming, especially with early

stocking of prawn, and using high-yielding rice varieties can significantly benefit farmers of the rice-

shrimp system in the coastal zone of Bangladesh.

Media grab

The integrated rice-GIFT-prawn farming, with stocking of freshwater prawn (M. rosenbergii) post-

larvae 60 days in advance of rice transplanting, and using high-yielding rice varieties, increases net

income by about 300% higher than the current wet season mono-rice crop practice in rotational

coastal rice-shrimp systems in Bangladesh.

Introduction

In Bangladesh, about 80% of aquaculture production of marine shrimp (P. monodon) comes from the

southwest inter-tidal coastal flatlands, where shrimp is grown in the dry season (February to mid-

August), in rotation with rice, which is grown in the wet season (mid-August to December ) when

water salinity is lowered by rainfall (Islam et al., 2005). Though alternate rice-shrimp system is one of

the more ecologically sustainable approaches to shrimp farming (Brennan et al., 2002), production of

shrimp in the rice-shrimp system in Bangladesh is low, from 29 to 277 kg/ha (Islam et al., 2005),

with a threat of frequent shrimp crop failures due to disease outbreaks. The rice production in this

system is also low, ranging from 1.0 to 3.0 t/ha (Karim, 2006), which is considerably lower than the

potential (Mondal et al., 2006). An increased yield of rice and integration of aquaculture production

with rice during the rainy season may improve coastal agricultural production and concomitant

livelihoods of farmers in coastal zones in Bangladesh.

The contribution of GIFT to net income from rice-aquaculture integration in fresh water (Hazrat et al.,

2003) and brackish water (Alam et al., 2007) environments has been reported as significant. Raising

freshwater prawn concurrently with rice in the wet season followed by shrimp monoculture in the dry

season has been proven an efficient farming system for increased income of coastal farmers in

Vietnam (Hung, 2001). Raising freshwater prawn in rainy season rice fields, however, has not been

economically successful in Bangladesh (Alam et al., 2007). This is probably because the rice

cultivation period is too short for the prawns to grow to marketable size. This can be overcome by

stocking prawn post-larvae (PL) before rice is transplanted in the fields, i.e. when water has not yet

completely become fresh. We postulated that this is possible, as the natural physiological requirement

of prawn larvae is to grow in brackish water and later in their life cycle as adults in fresh water. The

present study was conducted to assess the impact of: (1) using high-yielding rice varieties (HYV); (2)

integrating GIFT and prawn with rice; and (3) increasing the length of prawn grow-out period, through

advancing the stocking of prawn prior to stocking of GIFT and rice transplanting, on agriculture-

aquaculture production, and enhancing farmersrsquo; economic return.

Methods

The experiment was conducted in 12 farmersrsquo; rice-shrimp plots (locally termed as #39;ghers#39;), having

approximately an average area of 1150 m2 each, that were connected to the adjacent river with

103

sluice-operated canals. Each plot was developed with the construction of trenches along the inside

dykes, covering about 10% of the total land area with an average depth of 80 cm. Rice was

transplanted in the third week of August, after the harvest of the shrimp crop. The experiment had

three treatments of stock

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