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Open AccessArticle

Aerobic Rice with or without Strategic Irrigation in the Subtropics

1
Institute for Future Farming System, Central Queensland University, Rockhampton, QLD 4702, Australia
2
Centre for Agricultural Innovation, Department of Jobs, Precincts and Regions, Agriculture Victoria Research, 110 Natimuk Rd, Horsham, VIC 3400, Australia
*
Author to whom correspondence should be addressed.
Agronomy 2020, 10(11), 1831; https://doi.org/10.3390/agronomy10111831
Received: 28 October 2020 / Revised: 18 November 2020 / Accepted: 19 November 2020 / Published: 21 November 2020
(This article belongs to the Section Innovative Cropping Systems)
Modern rice varieties adapted to aerobic (dryland) conditions have expanded to new rice growing systems thanks to their plasticity in adapting to rainfed and irrigated conditions. This is important because, as water becomes scarce in paddy rice regions (as it is already in Australia), there will be a move towards tropical to subtropical dryland rainfed rice with attendant problems of drought and low temperature. To assess rice adaptability in the wet season of the semi-arid subtropical conditions of coastal central Queensland, field experiments were established for a late season (in January) planting in 2014 and early season planting in November 2015 with 13 varieties developed by Australian Agriculture Technologies (AAT) Ltd were seeded in a vertisol soil. This was to assess their adaptation to rainfed conditions and their response to strategic irrigation. Water scarcity and low temperature prior to and at flowering were important factors constraining yield. Early flowering varieties in the late season planting escaped the otherwise cold and drought stress during the reproductive stage and had higher yields. In the second year, earlier planting made possible with strategic irrigation avoided the low temperature constraint on yield, but without follow-up strategic irrigation, yields were still low. The average yield of varieties increased from 1.5 times (AAT 4) to 16.3 times (AAT 15) with strategic irrigation compared with rainfed yields averaged across years. The increase in yield with strategic irrigation was associated with a greater leaf area index, spikelet fertility, and instantaneous water use efficiency during flowering. Strategic irrigation concentrated roots in the top 15 cm, but differences in yield between varieties under rainfed conditions were not related to root properties. It is important to consider variations in flowering time, yield potential, and drought patterns when developing rice varieties for rainfed semi-arid tropical conditions, as well as when quantifying the benefits of strategic irrigation. View Full-Text
Keywords: rice; rainfed; drought; yield response; phenology rice; rainfed; drought; yield response; phenology
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Silwal, S.; Bhattarai, S.P.; Midmore, D.J. Aerobic Rice with or without Strategic Irrigation in the Subtropics. Agronomy 2020, 10, 1831.

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