No abstract

Exhaustive crops such as cotton require potassium (K) in copious amounts as compared to other crops. High yielding cultivars in cotton-wheat cropping system, have further increased its demand in cotton growing areas of Pakistan. As cotton is grown in arid and semiarid areas, therefore often prone to water deficiency. The reproductive growth particularly flowering and boll setting are highly sensitive to low soil water potentials, where enough K supply can play a vital role. In this two-year field studies, three cultivars (early, mid and late maturing) were cultivated at two K fertilizer levels 100, 200 kg K ha −1 along with control with no K fertilizer application at two irrigation levels. In first irrigation level, water was applied as per full irrigation schedule, while in water deficit irrigation water was applied at deficit irrigation schedule started after flowering till harvesting. It has been revealed that K application has impact on boll setting as well as seed cotton yield, however early and mid-maturing cultivars are more responsive to K fertilization. Furthermore, irrigation level had significant impact against K fertilization and relatively better response was observed in deficit irrigation as compared to full irrigation. Nevertheless, fiber quality parameters were unaffected by K fertilization. Considering the best benefit cost ratio under water deficiency, it is concluded that 100 kg K 2 O ha −1 should be applied at the time of seed bed preparation for economical seed-cotton yield of early maturing Bt cotton.

Arabidopsis AAL-toxin-resistant mutant atr1 shows enhanced tolerance to programmed cell death induced by reactive oxygen species Gechev, Tsanko S.; Ferwerda, MargFiet A.; Mehterov, Nikolay; Laloi, Christophe; Qureshi, Muhammad K.; Hille, Jacques

Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) is one of the major insect pests of stored grains. Due to export legislation and zero-tolerance for live insect in trade commodities, extensive use of synthetic insecticides is in practice in order to eliminate pest infestations from the lots. Currently, the one and only acceptable chemical to be used in stored grain is phosphine but due to its excessive usage the stored grain pests are becoming resistant against it. Hence discovery of alternative compounds is much needed. In this study we have compared insecticidal efficacy of different plant materials from six commonly grown plants of Pakistan, viz. Allium sativum (Alliaceae), Zingiber officinale (Zingiberaceae), Cymbopogon citratus (Poaceae), Eucalyptus globulus (Myrtaceae), Nicotiana tabacum (Solanaceae), and Azadirachta indica (Meliaceae) against T. castaneum infesting stored wheat, rice, corn and gram pulse. Various plant parts were dried, powdered, and used as admixtures to the stored commodities in the experiments. The results have suggested that A. sativum (garlic) and Z. officinale (ginger) were more effective resulting into 15 times higher adult mortality and 4 to 5 times reduction in grain weight losses when mixed with rice grains. Similarly, A. indica when admixture with wheat checked the population growth in the resources resulting into 3.5 times less adult production compared to controls. A subsequent experiment was conducted to study the dose response of neem seed powder against the beetle pest infesting milled products. Surprisingly, better control was observed either at lowest (1% w/w) or the highest doses (5% w/w). This finding is of great interest to understand the underlying phenomenon which we assume is the ability of T. castaneum to feed selectively in flour mediums, however, further research on this aspect is required to be investigated. The results of this study support the use of botanicals for stored product pest management.

Combining ability analysis was performed in order to identify high-yielding genotypes and hybrids. Six lines were crossed with three testers using a line × tester mating design. General combining ability (GCA) of parents, specific combining ability (SCA) of hybrids and gene action for several yield components and fibre were studied in the experiment. Additive gene action was observed in most traits except bolls/plant, sympodia/plant, monopodia/plant, total nodes, seed index, lint/seed, staple strength and seed cotton yield/plant which were influenced by non-additive gene action. GCA revealed that Giza-7 was a good general combiner for staple length, staple strength, seed index, boll weight, bolls/plant and monopodia/plant and BH-167 was good for ginning outturn (GOT) and sympodia/plant. Results of SCA values for hybrids indicated, that the cross Giza-7 × MNH-886 was a superior specific combiner for staple length, monopodia/plant, staple strength and seed cotton yield/plant; CIM-554 × CIM-557 for boll weight, sympodia/plant and lint weight/boll; BH-167 × MNH-886 for GOT and bolls/plant. Selection of such hybrids and good general combiners could be further exploited for yield improvement.