Phenology, Thermal Time Requirement, Growth and Yield of Winter Mungbean (Vigna Radiata) as Influenced by Sowing Dates in Ganges Tidal Floodplain (AEZ-13) in Bangladesh by Khairul Bashar HM in Open Access Journal of Biogeneric Science and Research
Abstract
A field study was carried out at the Regional Agricultural Research Station, Bangladesh Agricultural Research Institute, Rahmatpur, Barishal during the late Rabi season of 2018 in Ganges Tidal floodplain (AEZ 13). The experiment was carried out with four different sowing dates
(i) Sowing at January 15
(ii) Sowing at January 25
(iii) Sowing at February 05
(iv) Sowing at February 15 under randomized complete block design with three replications to study the phenology, thermal time requirement, growth and yield of mungbean.
BARI Mung-6 was used as the variety. The results revealed that mungbean sown on 15 January required the maximum days to reach maturity (87 days) whereas 15 February sown crop required the minimum days to reach maturity (71 days). The lowest accumulated GDD (Growing Degree Days) was observed at sowing on 05 February (1322.4 °C) followed by sowing on 25 January (1355.2 °C) whereas the highest accumulated GDD was observed at sowing at 15 January (1401.85 °C). The highest dry matter production at pod + flower part was sowing at 05 February (7.13g/plant) followed by sowing at 15 February (7.12g/plant) which were statistically identical, sowing at 05 February had produced the highest seed yield (1.73 tha-1) which was statistically identical to sowing at 15 February (1.70 tha-1).
Keywords: Sowing date; Phenology; GDD; Dry Matter Partitioning
Introduction
Mungbean (Vigna radiata) is an important component in the intensive crop production system for its short life cycle and is one of the leading pulse crops of Bangladesh. The agroecological condition of Bangladesh is favorable for growing this crop. It is a drought-tolerant crop and can be grown with a minimum supply of nutrients. Cultivation of mungbean can improve the physical, chemical, and biological properties of soil as well as are capable of fixing atmospheric nitrogen by the symbiotic process with the help of micro-symbiont (Rhizobium). Mungbean has good digestibility and flavor. Mungbean contains 51% carbohydrate, 26% protein, 10% moisture, 4% minerals and 3% vitamins [1]. In Ganges Tidal Floodplain of Barishal region, 184655 ha areas are under mungbean cultivation and area coverage is increasing every year. Among the mungbean varieties, the major cultivation area is covered by BARI Mung-6 (62%) e.g. 115241 ha.
Crop physiological processes dependent on integrated atmospheric parameters in which temperature is an important weather parameter that affects plant growth, development, and yield [2]. Several physiological and morphological changes occur that involve the development of root, shoot and leaves, flowering, and seed formation. Each physiological and morphological characteristic may affect yield in many ways, the net effect of which depends on other characteristics, on environmental conditions, and agronomic practices. Plant morphological characteristics and yield-forming components must be better understood if maximum yields are to be realized and exploited. Sowing time, a non- monetary input, is an important factor to influence yield [3]. Depending on sowing dates crop faces variable temperatures, rainfall, and relative humidity, etc. which affect crop phenology, growth, and yield. Temperature is a major environmental factor that determines the rate of plant development.
The phenological stages of mungbean are mainly related to temperature. Mungbean being a tropical and a sub-tropical crop requires warm temperature regimes (24 to 30°C with average temperature 28 °C) for its growth but can tolerate high temperatures up to 40°C. This temperature requirement for different developmental stages is known as thermal time or growing degree days (GDD). Sowing dates induced temperature variability may change the duration of phenophasic development. The duration of each phenophase determines the accumulation and partitioning of dry matter in different organs as well as grain yield. To understand the physiological basis of yield difference of mungbean, it is essential to quantify the components of growth, and the variation, if any, may be utilized in crop improvement. Climate change has deleterious effects on crop production in terms of the period of maturity and yield. From the last few years, the change in climate has been observed by Swaminathan and Kesavan (2012), which may adversely affect the phenology and production of crops [4]. With a successful study on these thermal indices may provide the information on the crop phenology and approximate date of crop harvest. Therefore, the present investigation was undertaken to evaluate phenological changes, growth, and yield of mungbean under variable sowing dates.
Materials and Methods
1.1. Description of the Study Area
The experiment was conducted at the Regional Agricultural Research Station, Bangladesh Agricultural Research Institute, Rahmatpur, Barishal at Ganges Tidal Floodplain ecosystem (AEZ-13) during the late Rabi season of 2018. The research station is situated in the southern part of Bangladesh and located at 220 42″ N Latitude to 900 23″ E Longitude at an altitude of 4 m from mean sea level (MSL). The climate of the locality is sub-tropical. It has characterized by high temperature, high humidity, and heavy rainfall during the Kharif season (April to September) and low rainfall associated with moderately low temperatures during the rabi season (October to March). The water balance is negative from November to April.
The study area is a piece of well-drained medium high land with even topography. The area belongs to the agro-ecological zone of the Ganges Tidal Floodplain under AEZ- 13. The texture of the soil is clay loam in nature with low organic matter content (0.54-2.58) and a pH value of 6.8-7.2. These areas are slightly saline (0.65-1.90 dS/m), with some pockets being non-saline.
1.2. Treatments and Experimental Design
The experiment was conducted in a single factor randomized complete block design with three replications. The treatments were as follows: Different sowing dates: (i) sowing at January 15 (ii) sowing at January 25 (iii) sowing at February 05 (iv) sowing on February 15. The unit plot size was 5m x 5m. Initially, the experimental area was divided into three blocks to represent three replications. Each replication contained four plots. Block to block and plot to plot distance was 1m and 0.5m respectively. BARI Mung-6 was selected as the variety. The experimental field was fertilized with 18-30-36-18 NPKS Kg/ha as a basal dose. Yield and different yield contributing characters were measured at harvest.
