Nadeem Akbar

Growth and physiology of basmati rice under conventional and water-saving production systems

ABSTRACT Conventionally flooded rice (CFR) requires enormous water and labor inputs. Water scarcity aspires for cultivation of water-saving rice. Growth response and physiology of basmati rice genotypes under the water-saving production systems has not been reported yet. Studies were conducted for 2 years to compare the growth and physiology of three rice cultivars (Super Basmati, Basmati-2000 and Shaheen Basmati), under high (CFR), medium (alternate wetting and drying [AWD]) and low water input (aerobic rice [AR]) systems. Leaf area index, crop growth rate, leaf area duration and dry matter accumulation were higher for AR followed by AWD and CFR, respectively. Shaheen Basmati had a lower growth and relative water contents than Super Basmati and Basmati-2000, probably due to its shorter stature and shorter life cycle. Photosynthetic rate and stomatal conductance of rice cultivars in the different production were affected only at reproductive stage. Basmati-2000 grown as AR had the highest photosynthetic rate followed by the same cultivar under AWD. The results of this study provide us an idea that basmati cultivars can attain a high growth and development with low water input. This would be helpful to grow rice successfully under water-short rice-growing environments.

Water management regimes alter Pb uptake and translocation in fragrant rice

Rice cultivation in lead (Pb) polluted soils often leads to high Pb contents in rice grains. The present study investigated the dynamics of Pb uptake under different water regimes in two fragrant rice cultivars i.e., Guixiangzhan and Nongxiang-18. Results revealed that water dynamics regulated the antioxidant activities in both rice cultivars under Pb toxicity. Compared to continuous ponding (CP), taken as control, alternate wetting and drying (AWD) reduced the Pb contents in roots, stems, leaves, and grains up to 17%, 41%, 22%, and 52% in Guixiangzhan and 23%, 19%, 17%, and 37% in Nongxiang-18, respectively. Furthermore, AWD-treatments reduced paddy yield from 11% to 21% in Guixiangzhan and 11-33% in Nongxiang-18 under Pb toxicity. In conclusion, Pb loadings in fragrant rice can be regulated by effective water management and/or by controlling irrigation water at different growth stages. Special control measures or management is required to cultivate the rice in metal(loid)s polluted soils.

PRODUCTION POTENTIAL OF VARIOUS MAIZE (Zea mays L.) HYBRIDS UNDER DIFFERENT INTRA-ROW PLANT SPACING

In Pakistan after wheat and rice, maize is 3 vital cereal crop. Globally maize is a staple food of many countries, in Pakistan maize is cultivated on 1,117 thousand hectares having 4,527 thousand tonnes production (GOP, 2014). At reproductive stage a high day temperature (36°C) affects pollination and grain formation of spring planted maize which results in reduced grain yield (Wahid et al., 2007). Different hybrids perform differently under various environmental conditions and agro-management practices. So hybrid selection is a critical management decision for corn growers. Selection of appropriate corn hybrid with high yielding potential can improve the probability of better grain yield at harvest (Thomison, 2008) although intensive management reduces plant stress allowing hybrids to yield closer to their genetic potential (Rouse, 2007). Higher grain yield is produced by newer maize hybrids as compared to old ones mainly because they can remain photosynthetically active longer than older hybrids especially during the grainfilling period. The refuse in photosynthetic activity of older hybrids during senescence is usually accredited to the deprivation of both structural and functional workings of chloroplasts (Ding et al., 2005). Plant spacing refers an important agronomic attribute as it plays an important role for the exploitation of the photosphere and rhizosphere by the plants. Maintaining the proper plant population is key factor for achieving the potential yield particulary in case of maize because it can’t produce tillers (Savage et al., 2004). An appropriate plant population may help more efficient utilization of all the renewable and nonrenewable resources for obtaining higher crop yields. Ogunlela et al. (2005) studied as increasing plant population delays maturity and decreases grains per cob, shelling percentage and 1000-grain weight. Planting geometry affects germination, growth and development of roots and water requirements of the crops. If the plants are arranged in an appropriate pattern then inputs such as water and nutrients are economically utilized (Ali et al., 1998). Increasing plant density per unit area positively influenced the grain yield but up to a certain limit, beyond which decline in mean yield per plant take place (Andrade et al., 1999). Increased plant population become the cause of lodging and creates great competition among the plants for sunlight, nutrients, water for proper growth (Sangoi, 2000). Plant density greatly affects the maize growth and development because it has competitive effect at vegetative and reproductive stages. Maize hybrids respond differently to different plant densities (Luque, 2006). Keeping in view the above facts, a study was conducted to investigate the performance of several maize hybrids under varying plant spacing. Pak. J. Agri. Sci., Vol. 54(1), 117-121; 2017 ISSN (Print) 0552-9034, ISSN (Online) 2076-0906 DOI:10.21162/PAKJAS/17.5000 http://www.pakjas.com.pk