Autumn Rice Research Articles

A comparative analysis of multitemporal MODIS EVI and NDVI data for large-scale rice yield estimation

Rice is one of the most important food crops worldwide, and large-scale rice yield estimation is thus critical for planners to formulate successful strategies to address food security and rice grain export issues. This study performed a comparative analysis of multitemporal Moderate Resolution Imaging Spectroradiometer (MODIS) enhanced vegetation index (EVI) and normalized difference index (NDVI) data for estimating rice crop yields in the Mekong River Delta (MRD), Vietnam. We processed the data for a 10-year period (2002–2011) following three main steps: (1) create a smooth time series of EVI and NDVI data, (2) formulate crop yield models, and (3) validate the model. The comparison results between EVI/NDVI-based estimated yields and the government's yield statistics indicated a significant relationship between the two datasets (p-value<0.001). The estimated results produced from EVI-based models were slightly more accurate than those from NDVI-based models, with the correlation coefficients (R2) ranging from 0.62 to 0.71 for spring–winter and 0.4 to 0.56 for summer–autumn rice crops, respectively. The root mean square error (RMSE) and mean absolute error (MAE) used to measure the model accuracy revealed the consistency between EVI-based estimated yields and the government's yield statistics. The RMSE values for winter–spring and summer–autumn crops were, respectively, 6.9–8.1% and 5.4–6.7%, and MAE values were 5.4–6.7% and 6.5–9.5%. There was, however, a significant correlation between the estimated yields obtained from EVI- and NDVI-based models (p-value<0.001), indicating no significant difference in the estimated yields between these two models. This study demonstrates advantages of using multitemporal MODIS EVI data for large-scale estimation of rice crop yields using the heading date in the MRD prior to the harvest period, and thus the methods could be transferable to other regions.

Arsenic Accumulation and Speciation in Transplanted Autumn Rice as Influenced by Source of Irrigation and Organic Manures

An effort has been made, through the present study, to take an account of arsenic (As) speciation in rice in the arsenic affected villages of Chakdaha block, Nadia district, West Bengal, India having an arsenic concentration of irrigation water drifted from the shallow tube wells 0.32 mg L−1. It appeared very clear from the present study that inorganic arsenic shared maximum arsenic load in rice straw while in grains it is considerably low. As species recovered from rice straw and grain are principally As-V and As-III and. Rice grain As has been found to be principally As-III while in straw As-V predominated over As-III. The results also shows that arsenic accumulation in different parts of rice remained in an order of root>leaf>shoot>grain. It was observed that incorporation of organic manures significantly reduced the arsenic uptake by different plant parts of rice is more pronounced and consistent with FYM and Vermicompost. Discussion of the health risk of As in rice has largely been based on its inorganic arsenic content because these species have generally been considered to be more toxic than MMA and DMA and can be directly compared to As in drinking water, assuming equal bioavailability of inorganic As in the rice matrix and in water. The maximum dietary risk of exposure to inorganic arsenic through transplanted autumn rice in the present experiment was calculated to be almost 700% of PTWI (Provisional Tolerable Weekly Intake) for an adult of 60 kg bodyweight.

Climatic water balance, probable rainfall, rice crop water requirements and cold periods in AER 12.0 in India

In this study an analysis was made on spatial variation of climatic water balance, (water surplus, actual evapotranspiration), probabilistic monthly monsoon rainfall and mapping of cold periods in agro-ecological region (AER) 12.0 of India using GIS and models. Since, rice is the dominant crop of the region, crop water requirements of rice was also spatially analyzed in different agro-ecological subregions (AESRs) of the AER 12.0 using CROPWAT 4.0 model and GIS. Study found that as per climatic water balance, large to moderate water surplus (520–70 mm) was available in AESR 12.1. The rainfall surplus of 220–370 mm was computed in AESR 12.2 and 370–520 mm in AESR 12.3 mm. Since winter rainfall is meagre and erratic, this amount of rainfall may be harvested and utilized for providing supplemental irrigation to winter crops or during dry spell of rainy season crops. Study also reveals that at 80% probability level (highly assured) in first month of southwest monsoon (June) 98–156 mm rainfall occurs in AESR 12.1, 103–144 mm in AESR 12.2 and 93–132 mm in AESR 12.3. These amounts of rainfall are sufficient to prepare land and sowing of direct seeded crops like maize, groundnut, blackgram, greengram, pigeonpea, cowpea, etc. that may be done from 24th standard week onwards (11th–7th June) after onset of southwest monsoon in the region. Based on existence of favorable temperature, among different AESRs, cold requiring crops may be tried in the districts of AER 12.1, but before cultivation of these crops, economic feasibility should be properly assessed. In normal rainfall year 450–550 mm, 600–720 mm and 775–875 mm crop water requirement was computed using CROPWAT 4.0 model for autumn rice, winter rice and summer rice, respectively in different AESRs of AER 12.0.

Effect of continuous cropping and integrated nutrient management practices on soil properties and yield of rice (Oryza sativa)rice cropping system in acid soil

The long-term effects of inorganic alone and combine effect of inorganic as well as organic sources of nutrients on soil fertility and crop productivity were investigated in rice (Oryza sativa L.)rice cropping sequence in acid soils of north-east India from 1987 to 2014. The higher average grain (6.50 t/ha) and straw (8.25 t/ha) yields of the rice rice sequence were recorded in case of 75% recommended nitrogen, phosphorus, and potassium (NPK) through fertilizers along with 25%N through incorporation of crop stubbles in winter rice at the time of puddling and 75% recommended NPK through fertilizers in autumn rice. The higher available N, P and K status of soil were recorded when recommended 50% NPK through chemical fertilizers applied along with 50%N through Azolla in winter rice and 100% recommended dose of NPK through chemical fertilizers to autumn rice. However, uptake of NPK by ricerice sequence was higher when 75% recommended NPK dose was applied through chemical fertilizers to both winter and autumn rice along with 25%N through crop stubbles only in case of winter rice. Thus, integrated nutrient management involving organic and inorganic sources not only increases the availability and uptake of ma- jor nutrients but also helps in yield sustainability in ricerice cropping system under long run in acid soils.

Crop water productivity of crop sequences involving rice (Oryza sativa), jute (Corchorus species) and vegetables in deep and shallow tube-well commands of lower Gangetic plains region

Eight rice (Oryza sativa L.)-based crop sequences were evaluatkd during 1999-2000 and 2000-2001 for their land and water productivity in tube-well commands of Lower Gangetic Plains Region. On rice-equivalent yield basis autumn rice-cabbage (Brassica oleracea L. convar. capitata (L.) Alef. var. capitatal-summer rice (24.6 tonneslha) or cauliflower [B. oleracea convar. botrytis (L.) Alef. var. botrytis L.1-pointed gourd (Trichosanthes dioca Rox b.)(23.4 tonneslha) crop sequences recorded significantly higher land productivity (LP) than other crop sequences like winter rice-wheat (Tn'ticum aestivum L. emend. Fiori &amp; Paol.)-jute (Corchorus sp.) (10.3 tonneslha) and winter rice-summer rice (1 1.7 tonneslha). Farm-level water productivity (WP) was computed on the basis of reference crop evapotranspiration (WP,) and water supply to fields (WP,). Winter vegetables recorded higher WP, (kg/m3) than summer-growing crop. The WP on the basis of ET was for cabbage 23.0, cauliflower 20.7, potato 18.8, tomato (Lycopersecon esculentum Miller nom. cons.)14.3, rice 1.6, wheat 2.1, sesame (Sesamum indicum L.) 0.4, jute 0.7 and pointed gourd 2.5 kg/m3. The WP values in terms of water supply (WP,) was 30-50% lower than potential WP,,. The WP in economic term (Rs/m3) was also high in vegetables (Rs 24.6-31.5) and its inclusion in rice-based crop sequence increased the water productivity by 2-3 times compared to other non-vegetable-based sequences. Irrigation water charge for crop production was 4-6 times higher under private owned shallow tube-well run by diesel than the government owned deep tube-well. In ST well commands water cost (WC) for cultivation was much higher in winter rice-summer rice or autumn rice- cabbage-summer rice sequences (Rs 8-13 thousandlha) than autumn rice-tomato or other sequences. Inclusion of summer rice in the rice-rice system increased the WC for produce (Rs 57.7-71.8 q) in tubewell- irrigated ecosystem.

Fibre yiedl of mutants of white jute ( Corchorus capsularis) with altered phenological development patterns

The standard cultivar, D-154, and one early-flowering and four late-flowering mutants derived from it were sown at a central location in Bangladesh on seven occasions at 15 or 16-day intervals in 1978 and 1979. The objective was to determine whether any mutant could provide a higher yield of well-matured fibre at an earlier date than D-154. Fibre yield and strength are maximal at the beginning of capsule development, and harvest should be completed by August 15, so that the yield of the following transplanted autumn rice crop is maximized. Two sowing times, March 17 and April 3, spanned the normal sowing time, two were earlier, and three were later. Records were made of the dates at which 50% of plants per sub-plot were flowering, and also at 90% flowering and 50% capsule formation. Plants were harvested at these three stages for all sowing-time/genotype combinations. Plant height, basal diameter of the stems and fibre yield were measured. Sowing time and genotype had major effects on the duration of the vegetative and flowering phases. D-154 reached the optimal harvest stage by August 15 only when sown about March 1. Three mutants, C-28, C-36 and ‘Atompat-38’, were at least 20% higher-yielding than D-154 at those dates of sowing and harvest, but the fibre of the mutants was somewhat less mature. One of these mutants, C-28, also yielded 17% more than D-154 when sown in mid-March, which is the beginning of the normal sowing time. The early-flowering mutant was low-yielding, but would be useful for late sowing. Further improvement of jute by mutation and conventional breeding is discussed.

Influence of rice crop, climate and lunar cycles on the population patterns of Scirpophaga nivella

—Nightly catches of Scirpophaga nivella (F.) in light traps in rice plots in West Bengal, India, showed two discrete peaks of abundance in each trap-year corresponding to congenial weather and abundance of summer (mid-March-mid-June) and autumn (mid-July-mid-November) rice plants. Estimated generation times showed many overlapping generations in each trap a year. Variations in summer catches were significantly correlated (P < 0.01–0.05) with maximum temperature and minimum relative humidity of the day, and minimum temperature and wind speed of the night; whereas those in autumn catches were significantly associated with maximum temperature and minimum relative humidity of the night (P < 0.01–0.05). Autumn crops had more infestations, and sustained greater larval density than summer ones. Females were twice as heavy as males (2.1:1) and adults were heavier in October than in May. Catches of immature and mature females were consistently maximum at full moon and new moon, respectively.

Adaptability of exotic and local accessions of mungbean (Vigna radiata (L.) Wilczek) to variation in sowing time in Bangladesh

Sixty exotic and local strains of Vigna radiata (L.) Wilczek were sown twice monthly throughout 1 year in central Bangladesh. “Summer” strains matured quickly, i.e. in about 40 days, only if sown in August–September, when the main crop is sown after jute and before wheat. The most extreme accessions in this group did not flower for at least 90 days when sown in December or January. “Modified summer” types, having either synchronous or asynchronous flowering and pod development, flowered 30–60 days after sowing at any time of the year. A smaller group of “winter” strains flowered within 3 months only if sown between August and March. Some high-yielding, early strains were identified for sowing in August–September, and others for sowing in April to replace the fallow phase now preceding autumn rice in the north-west (Barind) region. The results are discussed in relation to future introduction and breeding programmes.

Effect of indirect manuring on the yield of broadcast Rice in Malabar

In Malabar for autumn rice, occupying about three lakh acres in double-crop lands, broadcast sowing is the rule in more than 75 per cent of the area. Preparation of the land begins immediately after the harvest of second-crop paddy in January and repeated ploughings are given with the receipt of every summer shower thereafter. The soil is thus brought into a fine tilth before the seeds are sown in April-May, following a soaking rain. This practice precludes raising of a green manure crop on the lands. Other bulky organic manures are also not applied usually, for fear of wash of the added manurial ingredients in the torrential rains of the South-West monsoon. The good tilth that is produced by bringing the soil into a fine state of division by a scrupulous attention to preparatory cultivation, brings in a normal yield, provided the distribution of pre-monsoon showers remains normal. Increased yields are also obtained by top dressing with ammonium sulphate; this practice having come into vogue in recent times.