High ambient temperature is one of the most alarming climatic factors in challenging the productivity and sustainability of crops worldwide. An effective way to cope this problem is the development of climate smart, heat resilient maize hybrids through evaluating the cultivated germplasm. The main objective of current study was to evaluate local and multinational maize hybrids for their performance under optimal and heat stress conditions and to devise a selection criterion for the identification of heat tolerant maize hybrids. Nine maize hybrids, including local and multinational, were evaluated under optimal and heat stress conditions across three consecutive spring seasons (2017-18, 2018-19 and 2019-20) at Maize and Millets Research Institute, Yusafwala, Sahiwal. Results revealed the presence of highly significant differences among maize hybrids under both conditions and for all three seasons. Kernel yield was found to be highly correlated with net photosynthetic rate (0.735 ** ), shelling percentage (0.910 ** ) and relative cell injury percentage (-0.775 ** ) under stress conditions. Cluster and biplot analysis unveiled that two local maize hybrids YH-5507 and YH-5427 were highly heat tolerant while multinational hybrids i.e. NK-8711, P-1543 and DK-6724 were highly productive under control/optimal conditions only. These hybrids can be invaluable sources of genes/alleles for the development of climate smart maize genotypes.
The current study was conducted to evaluate maize hybrids for their high temperature tolerance ability based on their performance as assessed through different high temperature stress indices. Nine maize hybrids were screened under optimal and high temperature stress conditions (late sowing) for three consecutive spring seasons (Spring 2017(Spring -18, 2018(Spring -19 and 2019, laid out under split-split-plot design under RCBD. Results reveled significant differences among stress indices for all three seasons and both conditions. Correlation analysis indicated that some high temperature stress indices i.e., STI, MP, GMP and HARM had a strong positive correlation with kernel yield under normal (Yp) and high temperature stress conditions (Ys). Biplot analysis further unveiled that two local maize hybrids i.e., YH-5507 and YH-5427 were the most productive, stable and heat tolerant while YH-5532, P-1543 and NK-8711 showed poor performance under high temperature stress conditions as compared to normal sowing. High temperature stress indices could be efficiently used to screen heat tolerant genotypes.
Complex nature of nitrogen fertilizer in soil and poor management practices are major causes of low fertilizer use efficiency in Pakistan. These factors further increases nitrogen losses in form of nitrate leaching and volatilization of ammonium, as well as nitric oxide which are burning economic and environmental threats. Keeping in view the demand of urea application in Pakistan and its low efficiency, we hypothized that appropriate urea management with neem formulations or biofertilizers can enhance the nitrogen use efficiency. We designed experiment with treatments: T0 (N0 application), T1 (recommended nitrogen), T2 (recommended nitrogen + biofertilizer), T3 (recommended nitrogen + neem seed extract), T4 (75% recommended nitrogen + biofertilizer), T5 (75% recommended nitrogen + neem seed extract), T6 (recommended nitrogen + biofertilizer + neem seed extract), T7 (75% recommended nitrogen + biofertilizer + neem seed extract) in wheat crop. The experiment was laid out in randomized complete block design (RCBD) with split plot arrangements. Different approaches for stabilized nitrogen fertilizer responded significantly for the wheat plant height, tillers per plant, number of grains per spike, 1000-grain yield, grain yield and harvest index. Result exhibited that wheat crop enhanced yield attributes and finally the yield under treatment T6 and T7 for both wheat cultivars. Treatments comparison with recommended nitrogen (T1) revealed that all treatments with biofertilizer, as well as with neem seed, enhanced crop performance along with nitrogen use efficiency. It can be concluded that nitrogen fertilizer can be stabilized in the soil with the use of different natural products for sustainable crop production.
Sustainable maize production under changing climatic conditions, especially heat and water stress conditions is one of the key challenges that need to be addressed immediately. The current field study was designed to evaluate the impact of water stress on morpho-physiological, biochemical, reactive oxygen species, antioxidant activity and kernel quality traits at different plant growth stages in maize hybrids. Four indigenous i.e., YH-5427, YH-5482, YH-5395, JPL-1908, and one multinational maize hybrid i.e., NK-8441 (Syngenta Seeds) were used for the study. Four stress treatments (i) Control (ii) 3-week water stress at pre-flowering stage (iii) 3-week water stress at anthesis stage (iv) 3-week water stress at grain filling/post-anthesis stage. The presence of significant oxidative stress was revealed by the overproduction of reactive oxygen species (ROXs) i.e., H2O2 (1.9 to 5.8 µmole g−1 FW) and malondialdehyde (120.5 to 169.0 nmole g−1 FW) leading to severe negative impacts on kernel yield. Moreover, a severe reduction in photosynthetic ability (50.6%, from 34.0 to 16.8 µmole m−2 s−1), lower transpirational rate (31.3%, from 3.2 to 2.2 mmol m−2 s−1), alterations in plant anatomy, reduced pigments stability, and deterioration of kernel quality was attributed to water stress. Water stress affected all the three studied growth stages, the pre-flowering stage being the most vulnerable while the post-anthesis stage was the least affected stage to drought stress. Antioxidant activity was observed to increase under all stress conditions in all maize hybrids, however, the highest antioxidant activity was recorded at the anthesis stage and in maize hybrids YH-5427 i.e., T-SOD activity was increased by 61.3% from 37.5 U mg−1 pro to 60.5 U mg−1 pro while CAT activity was maximum under water stress conditions 8.3 U mg−1 pro as compared to 10.3 U mg−1 pro under control (19.3%). The overall performance of maize hybrid YH-5427 was much more promising than other hybrids, attributed to its higher photosynthetic activity, and better antioxidant defense mechanism. Therefore, this hybrid could be recommended for cultivation in drought-prone areas.
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