• Energy Research

The objective of this article is to review: (a) the principles that underpin conservation agriculture (CA) ecologically and operationally; (b) the potential benefits that can be harnessed through CA systems in the dry Mediterranean climate; (c) current status of adoption and spread of CA in the dry Mediterranean climate countries; and (d) opportunities for CA in the Central and West Asia and North Africa (CWANA) region. CA, comprising minimum mechanical soil disturbance and no-tillage seeding, organic mulch cover, and crop diversification is now practised on some 125 million ha, corresponding to about 9% of the global arable cropped land. The area under CA is spread across all continents and many agro-ecologies, including the dry Mediterranean climate. Empirical and scientific evidence is presented to show that significant productivity, economic, social and environmental benefits exist that can be harnessed through the adoption of CA in the dry Mediterranean climates, including those in the CWANA region. The benefits include: higher productivity and income; climate change adaptation and reduced vulnerability to the erratic rainfall distribution; and reduced greenhouse gas emissions. CA is now spread across several Mediterranean climate countries outside the Mediterranean basin particularly in South America, South Africa and Australia. In the CWANA region, CA is perceived to be a powerful tool of sustainable land management but it has not yet taken off in a serious manner except in Kazakhstan. Research on CA in the CWANA region has shown that there are opportunities for CA adoption in rainfed and irrigated farming systems involving arable and perennial crops as well as livestock.

Leaf growth is one of the first physiological processes affected by changes in plant water status under drought. A decrease in leaf expansion rate usually precedes any reduction in stomatal conductance or photosynthesis. Changes in leaf size and stomatal opening are potential adaptive mechanisms, which may help avoid drought by reducing transpiration rate, and can be used to improve rice genotypes in water-saving cultivation. The indica rice cultivar IR64 and four of its near-isogenic lines (NILs; BC(3)-derived lines) unique for leaf size traits, YTK 124 (long leaves), YTK 127 (broad leaves), YTK 205 (short leaves) and YTK 214 (narrow leaves), were compared in this study for changes in leaf growth and its water status. The plants were subjected to two soil water regimes, well-watered and progressive soil drying measured by the fraction of transpirable soil water (FTSW). Applied drought reduced leaf number, total leaf area, specific leaf area, plant biomass, tiller number, plant height, stomatal conductance, amount of water transpired, leaf relative water content, and leaf water potential more in IR64 and the NILs than in the respective controls; nonetheless, transpiration efficiency (TE) was slightly higher under drought than in the well-watered controls. NILs with broader leaves had higher biomass (and its individual components), less stomatal conductance, and higher TE under drought than NILs with narrow and shorter leaves. Under drought, leaf number was positively correlated with tiller number and plant height; nonetheless, root weight and total biomass, water transpired and TE, and plant height and TE were positively correlated with each other. However, a negative correlation was observed between stomatal conductance and the FTSW threshold at which normalized transpiration started to decline during soil drying. Overall, the IR64-derived lines with broader leaves performed better than NILs with narrow and short leaves under drought.

This book features a comprehensive foresight assessment, exploring the pressures — threats as well as opportunities — on the global agriculture & food systems between now and 2050. The overarching aim is to help readers understand the context, by analyzing global trends and anticipating change for better planning and constructing pathways from the present to the future by focusing on the right questions and problems. The book contextualizes the role of international agricultural research in addressing the complex challenges posed by UN 2030 Agenda and beyond, and identifies the decisions that scientific leaders, donors and policy makers need to take today, and in the years ahead, to ensure that a global population rising to nine billion or more combined with rising incomes and changing diets can be fed sustainably and equitably, in the face of the growing climate threats.