H. Rehman

Zinc nutrition in rice production systems: a review

BackgroundZinc (Zn) deficiency is one of the important abiotic factors limiting rice productivity worldwide and also a widespread nutritional disorder affecting human health. Given that rice is a staple for populations in many countries, studies of Zn dynamics and management in rice soils is of great importance.ScopeChanging climate is forcing the growers to switch from conventional rice transplanting in flooded soils to water-saving cultivation, including aerobic rice culture and alternate wetting and drying system. As soil properties are changed with altered soil and water management, which is likely to affect Zn solubility and plant availability and should be considered before Zn management in rice. In this review, we critically appraise the role of Zn in plant biology and its dynamics in soil and rice production systems. Strategies and options to improve Zn uptake and partitioning efficiency in rice by using agronomic, breeding and biotechnological tools are also discussed.ConclusionsAlthough soil application of inorganic Zn fertilizers is widely used, organic and chelated sources are better from economic and environmental perspectives. Use of other methods of Zn application (such as seed treatment, foliar application etc., in association with mycorrhizal fungi) may improve Zn-use efficiency in rice. Conventional breeding together with modern genomic and biotechnological tools may result in development of Zn-efficient rice genotypes that should be used in conjunction with judicious fertilization to optimize rice yield and grain Zn content.

Seed Priming with Polyamines Improves the Germination and Early Seedling Growth in Fine Rice

ABSTRACT Pre-sowing polyamine seed treatments were employed in fine rice (Oryza sativa) to explore the possibility of improving germination and early seedling growth. Fine rice (cv. Super-basmati) seeds were soaked in 10 and 20 ppm aerated solutions of spermidine, putrescine and spermine for 48-h at 28 ± 2 C. Polyamine seed treatments resulted in earlier, synchronized and enhanced germination. Improvement in shoot and root length, seedling fresh and dry weight, and root and leaf score, was also observed in seeds treated with polyamines. Seed treatment with 10 ppm putrescine solution was the most effective for most of the attributes studied.

Exogenous glycinebetaine application improves yield under water-limited conditions in hybrid sunflower

Limited water availability is a severe threat to the sustainability of crop production. Exogenous application of glycinebetaine (GB) has been found very effective in reducing the adverse affects of water scarcity. This study was conducted to examine the role of exogenous GB application in improving the yield of hybrid sunflower (Helianthus annuus L.) under different irrigation regimes. There were three levels of irrigation: Control (four irrigations), three irrigations (irrigation missing at budding stage) and two irrigations (irrigation missing at budding and grain formation stage) in the experiment. While GB was applied exogenously at 100 mM GB each at budding and grain formation stages, the Control treatment did not receive any GB application. Data regarding yield, yield components and quality parameters showed that water stress reduced the head diameter, number of achene per head, 1000-achene weight and yield. Nonetheless, it was significantly improved by the exogenous GB application. Among the qualitative characteristics, protein contents were significantly increased by water stress at different growth stages but were reduced by exogenous GB application. Whilst oil contents were reduced by drought at different stages, GB application, however, did not ameliorate the negative effect of drought stress on achene oil contents. The effects of water stress and foliar application of GB were more pronounced when applied at vegetative stage than at the reproductive stage. Moreover, exogenous GB application was only advantageous under stress conditions.

Conservation Agriculture in South Asia

Conventional agriculture has put forth soil and crop sustainability to substantial soil degradation resulting in a concomitant decrease in the productivity of these systems. Conservation agriculture (CA) including minimum soil disturbance, permanent soil cover, and diversified crop rotations aimed to decrease and/or revert the effects of conventional farming practices like soil organic matter decline, soil erosion, soil physical degradation, and fuel use. However, in South Asia, the area under CA is very small compared to the rest of the world. The history of CA in South Asia starts when wheat plantation with zero tillage was first introduced in Indian and Pakistani Punjab in the 1980s. Currently, conservation tillage is being practiced on more than 5 M ha in Indo-Gangetic plains of South Asia. Conservation tillage reduced greenhouse gas emission and the production cost, and improved the soil health and crop yields. However, challenges like cultural and economic entrenchment of tillage agriculture in this region, weeds, insect pests, diseases, crop residue management, and reduced availability of suitable seeding and planting equipment are hindering its uptake. In this scenario, problem-oriented research and training, provision of conservation machinery at specific sites at proper time at affordable rates, and aggressive extension campaigns may help to boost up the uptake of CA in South Asia.