Keywords: Aerobic rice, water productivity, pre-flowering phenology, eco-efficiency, perceptions, transformational technology, food security, resource constraints, Punjab, Pakistan.
Just like in many other parts of the world, diminishing resources of water, labour and energy threaten the sustainability of conventional flooded rice systems in Pakistan. Changing the current production system to non-flooded aerobic rice could considerably increase resource-use efficiencies. However, for subtropical conditions, such as those in South Asia, the non-conventional system is still very much in the development phase. The main objective of this study was to evaluate the aerobic rice system of the Punjab in Pakistan from a biophysical and socio-technological perspective. I employed a combined approach of experimentation and farmer surveys to contribute important information on aerobic rice crop performance, pre-flowering photothermal responses, and farmers’ perspective.
Two seasons of field experiments (2009 and 2010) at the research station of the University of Agriculture, Faisalabad–Pakistan tested local (KSK133, IR6, RSP1) and exotic (Apo, IR74371-54-1-1) genotypes against different combinations of irrigation levels (high, moderate, low) and nitrogen rates (0, 170, 220 kg N ha−1). Under aerobic conditions, the water productivity (WPg; g grain kg–1 total water input) improved significantly, showing a potential water saving of about 20%. However, this improved water productivity was at the cost of declining land productivity, as the actual production per unit area decreased. Grain yield and total aboveground N uptake were mainly limited by irrigation and not by N. The results suggest significant losses of applied N, and indicate that improvements in N use efficiency might be expected if N application is better synchronised with the N-demand of the crop.
Accurate knowledge on rice phenological development is an important feature when the aim is to better match supply and demand for further improvement in resource use efficiencies. A controlled-environment growth chamber study, aimed at estimating pre-flowering photothermal responses, gave a robust set of photoperiod-parameters and demonstrated that all four tested genotypes (KSK133, RSP1, Apo, IR74371-54-1-1) were strongly photoperiod-sensitive. The temperature range in the field experiments was too narrow to achieve convergence to a unique set of optimal temperature response parameters. Yet, sensitivity analysis clearly showed that commonly used standard cardinal temperatures (base, optimum, maximum: 8, 30, 42°C, respectively) overestimated the time to flowering. Data obtained under a wider range of temperatures should result in more accurate estimation of temperature response parameters.
To supplement the basic biophysical research, I conducted farmer surveys (n=215) in three major cropping systems viz. rice-wheat, mixed-cropping and cotton-wheat to understand farmers’ perspective about the future prospects of aerobic rice system. Most of the farmers were unaware of aerobic rice technology but expressed their keen interest in experimenting. Farmers perceived aerobic rice as a system to improve resource use efficiency particularly for labour and water but they consider it a knowledge intensive system requiring careful and timely management practices especially for weeds. The unavailability of suitable fine grain aerobic basmati varieties was identified as a major constraint for large scale adoption. Understanding farmers’ perspective helped to develop guidelinesfor the emerging aerobic rice system. The aerobic rice system is a rational approach for improving WPg and eco-efficiencies of water, labour and energy. Associated risks of crop failure can be reduced by filling the identified knowledge and technological gaps through additional research and adequate training of farmers.
|Qualification||Doctor of Philosophy|
|Award date||16 Oct 2013|
|Place of Publication||S.l.|
|Publication status||Published - 2013|
- oryza sativa
- farming systems
- resource utilization
- use efficiency
- water use efficiency
- food security