Abstract
The present study assesses the response of hybrid rice (variety Arize 6444) to potassium (K) application during rainy (wet) seasons of 2016 and 2017 in coastal saline soils of West Bengal, India. The study was conducted at the Regional Research Farm, Bidhan Chandra Krishi Viswavidyalaya, Kakdwip, West Bengal. The soil is clayeywith acidic pH (5.91), saline (Electrical conductivity/EC 1.53 dS m−1) and of high K fertility (366 kg ha−1). The experimental plots were laid out in a randomized complete block design with five (5) K treatments (0, 30, 60, 90, and 120 kg K2O ha−1) with four replications. Plant height, dry matter (DM) in different plant parts, number of tillers, and grain yield were measured in each treatment for the determination of optimum K dose. The study revealed that the stem, leaf, and grain dry matter production at 60 days after transplanting (DAT) and harvest were significantly (p ≤ 0.05) higher at 90 kg K2O ha−1 application. The number of tillers hill−1 was also higher (p ≤ 0.05) in plants fertilized with 90 kg K2O ha−1 over K omission. At harvest, grain K concentration improved (p ≤ 0.05) with K fertilization at 90 kg K2O ha−1, 116% more than the zero-K. Omission of K application from the best treatment (90 kg K2O ha−1) reduced grain yield by 3.5 t ha−1 even though the available K content was high. Potassium uptake restriction due to higher Mg content in the soil may have caused reduced uptake of K leading to yield losses. The present study also showed higher profits with 90 kg K2O ha−1 with higher net returns (US$ 452 ha−1) and benefit:cost ratio (1.75) over other treatments from hybrid rice (var. Arize 6444). From the regression equation, the economic optimum level of K (Kopt) was derived as 101.5 kg K2O ha−1 that could improve productivity of hybrid rice during the wet season in coastal saline soils of West Bengal.
Highlights
With growing population and urbanization, the total area under rice cultivation in India as well as in the state of West Bengal is decreasing at a rapid rate
Arize 6444) were significantly (p ≤ 0.05) influenced by K application levels (Table 2); grain yield increased with the increase in K level from 0 to 90 kg K2 O ha−1
The grain yield obtained with 90 kg K2 O ha−1 was 85% more than the yield obtained with control
Summary
With growing population and urbanization, the total area under rice cultivation in India as well as in the state of West Bengal is decreasing at a rapid rate. Medium and low lands in the eastern part of India leave no other option for farmers but to go for rice cultivation in the rainy (khairf /wet) season. Rice is grown in about 1 million hectares under the coastal ecosystem of West. Salinity is a major yield-reducing factor in thecoastal ecosystems for rice [3]. The productivity of rice is not satisfactory in the coastal areas due to aberrant climatic conditionsand non-availability of hybrid varieties [6]. Water stagnation (medium-deep, 25–50 cm) for most of the crop growing season, flash floods (complete submergence for 1–2 weeks), and water and soil salinity [7] are typical deterrents to high productivity. Considering the demand–supply gap of rice, adoption of superior rice varieties could be effective for narrowing yield gap, and for breaking the yield ceiling in the coastal ecosystem
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