Water productivity and yield of Paddy Rice cultivation under AWD irrigation management in Pingtung, southern Taiwan
Abstract
Decreasing water input while maintaining grain yield remains a challenge for World to produce rice sustainably. In recent years, the Alternate wetting and Drying Irrigation(AWD)has been developed toward Asian’ farmers. However, the gap observed is the low assessment of its performances, particularly in Taiwan. The aim of this study is to determine whether AWDI management could maintain grain yield with reduced water input. AWD approach experiment field was conducted in National Pingtung University, in Southern Taiwan. A two leaves old rice seedling, TAINAN11 was arranged in a randomized complete block design with five water treatments: AWD , 2cm AWD , AWD , AWD and AWD with respectively 2cm and 3 cm water depth monitoring by soil hairline 3cm 3cm/w 4cm 5cm cracks; 3cm, 4 cm, and 5cm weekly irrigation. The irrigation regimes were done by AWD technics. The plant water status was assessed through soil water content. Crop growth, grain yield, and water productivity were measured. The results showed that grain yields under AWD , AWD and AWD presented the high yield and irrigation water 3cm 2cm 3cm/wproductivity about 0.211, 0.208 and 0.205 respectively. The AWD and AWD despite the high-water depth 4cm 5cm presented low yield with respectively 3081 Kg/ha and 2604 Kg/ha.
The results confirmed also that AWD3cm and more precisely AWD could obtain comparable grain yield close to 3cm/wfarmers practices with fewer irrigations. These findings suggested that AWD with 3 cm water depth (AWD and 3cm AWD ) could be used for water-saving while maintaining grain yield in paddy rice production. 3cm/w
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Introduction
The 2017’sedition of The State of Food Security and Nutrition in the World reveled that in 2016, the number of undernourished people in the world increased to an estimated 815 million, up from 777 million in 2015 but still down from about 900 million in the year 2000[1]. It’swell known that rice (Oryza sativa L.)is a staple food for nearly half of the world’sseven billion people particularly in Asia, and this alimentary need must be satisfy by doubling the present production over 2030 [2].
The fresh water, one the indispensable input in rice production, is a finite resource which is faced to the increasing large demand of Agriculture. The per capita available water resources in Asia are expected to decline by 15-54 % compared with 1990 [3] and already 12 million hectares of south Asia’sirrigated rice are at risk of severe water shortage. In Taiwan were rice is avery important and valuable crop, with a total yield of more than 1.73 million tons[4], the possibilities of sustainable production are welcome. Indeed, Rice is grown from February to July, and August to December [5], but according to Kuo andal., (2006) [6] the amount of water available for agricultural use has recently become critical.
Agriculture is now faced with the challenge of securely delivering sufficient food to meet the projected demands of population growth and overcoming issues such as climate change and water scarcity through sustainable agricultural intensification ([7]. This poses major challenges for scientists, extension workers, and farmers. Numerous technologies have been developed with the aim to reduce water use and help the farmers in rice production with higher water productivity ([8] and [9]). One of these technologies is the Alternate Wetting and Drying (AWD) which has been developed since the 1970s [10]- [9]. The concept of AWD technology is based on the fact that rice high yields can be obtained by just providing the only need water to the crop. In 2015 and 2016 afield experiment was conducted in southern of Taiwan by KIMA andal., (2015) [11] and Pascual andal., (2016) [12] respectively, to determine the most suitable ponded water depth for enhancing water saving in paddy rice irrigation. The firsts found that lowest water reduced yield component between 15-32%. They mentioned that weekly application of 3cm water depth combined with rainfall improved AWD effectiveness and yielded the highest beneficial water productivity with less yield expenses. The seconds showed that the highest total water productivity, (0.75 kg/m3) and irrigation water productivity (1.40 Kg/m3) was achieved in T cm. They also found that weekly 2 application ofT cm ponded water depth produced the lowest yield reduction (1.57%) and grain production loss 4 (0.06 kg), having no significant impact on yield loss compared toT cm. 5 Due to some uncertainties from the two previous studies, in 2017, Kissou and al.,[13] conducted a similar experiment during the dry season. Their results shown that 3 cm water depth gave the best results in terms of water saving, high yield, but some uncertainties underlined were the closeness of these results with the 4 cm water depth. Therefore, the present experiment was conducted applying the AWDto more clarify these findings.
The objective of this study was to determine whether the AWD irrigation management could maintain grain yield with less water use. It was specifically expected to determine the water input (quantity and frequency) and the water productivity;and its effect on agronomic traits and grain yield.
Conclusion
The present survey was conducted during a dry season with the aim to improve the AWD capacities as water-saver for yield improvement. Five irrigation treatment were design and realized in NPUST irrigation experiment station. The applying of twice-weekly irrigation water depth of about 2 cm and 3cm and the monitoring of the soil hairline cracks as an indicator of water status known in farmer practice, showed good results. The yield result was good correlated to the water treatment with a probability ofabout 0.825. The treatment AWD , a weekly single irrigation 3/wunderlined as the optimum irrigation depth by previous studies, presented some results closed to AWD and AWD with 2 3 high grain yield.
The marketable yield obtained tend to below than those presented in other studies. The possible effects of the climatic parameters throughout the rice cycle may explain this yield value. From nursery to seedling and tillering ages, rice plant suffered about temperature fluctuation, specifically the cold. The daily variation of temperature largely influenced the growth of rice plants leading to lengthening of rice reproduction cycle and then a more consumption of water and other resources. One of the consequence is also the reduction of the water productivity even if the rate found was positive (0.208 to 0.132 respectively from SR to SR ). 2cm 5cm Despite of the weather influence, the irrigation management ensured a good productivity of yield and water. The IWP and the RWP registered an average of 0.208 and 1.623 respectively for AWD , AWD , and AWD . AWD , and AWD 2 3 3/w 4 5 have an average of 0.152 and 1.275 of irrigation and rainwater productivity.
Regarding to the yield performance and the water used efficiency, rice grown with AWD methods reveals a lot of opportunities in rice farming system. Under drought condition, adaptation capacity of rice plant can give good yields and water productivity. The results of this study open some perspectives forricecultivation performing on different periods.