PJB-2021-707
Optimization of maize productivity for sowing times and N-levels under changing weather
Abdullah Shah
Abstract
Fluctuation in solar radiation resulted in changes of heat intensity and photoperiod within a location. The climate change is an ongoing process which affects other than so many things, the solar radiation in an agro-ecological conditions for crop growth and hence its productivity. Report on Khyber Pakhtunkhwa (KP), available in the climate change center the University of Agriculture Peshawar confirms that rain fall in summer will be expands with a reduction in winter season. Similarly the temperature will show an increase from 2005 to 2040 (Ali et al, 2021). This would definitely affects the crops growth and development and hence the yield. Maize is the major summer crop of Pakistan and of the KP but its yield is lower in KP than Pakistan. Moreover, its production cost is also higher due to many other reasons including the inputs (nutrients). In developing countries the major hurdles that cause the reduction in maize productivity are sowing timings and nutrients application. Pakistani soils and climatic conditions are suitable for maize production, but yield is less due to inappropriate selection of optimum sowing time and nitrogen availability. When temperature is unsuitable for growth, the early maturing cultivar unable to fully utilize the solar radiation, therefore fail to explore potential of inputs provided during growing season. Nitrogen (N) fertilizer availability is closely associated with rainfall and/or irrigation water in season. Production cost increase with the application of excessive nitrogen (N) instead of increasing maize yield. To optimize the maize yield for different sowing times and N-levels under changing weather of Peshawar a field study was conducted. Field experiment was conducted at Agronomy Research Farm, The University of Agriculture Peshawar, Pakistan during summer season 2017 and was repeated in summer 2018 to evaluate the effect of optimum sowing timings and nitrogen rates for maize addressing the grain yield and quality. A randomized complete block design (RCBD) in split plots arrangement was used for the study having three replications. Sowing timings were effective from June to July with 10 days interval in the season. Nitrogen rates (NR) were control (i.e. No N), 160, 180, 200 and 220 kg ha-1 given in three equal splits (i.e. 50% at sowing), 25% one month after sowing and 25 % a week before tasseling of the crop from urea source. Means values of the data showed that significant (P<0.05) reduction in days to tasselings, silking and physiological maturity was observed with a 10 days delay in sowing made from June 6 to July 16 and with a reduction in NL application starting from 220 to 160 kg ha-1. Moreover maximum plant height, ear height and ear length was observed when the sowing made early in the month of June with the application of 220 kg N ha-1. Nitrogen use efficiency (NUE) and leaf area index were significantly decrease (P<0.05) with a 10 delay, in sowing made on from June 6 to July 16, with NL application starting from 220 kg to 160 kg ha-1, the lowest in control where no N was applied. Yield traits (i.e. grain ear-1, grain row-1 and grain weight) were observed maximum when the sowing made in early June with the application of 220 and 200 kg N ha-1. Biomass and grain yield decreased (P<0.05) when the sowing delay with a 10 days interval starting from June 6 to July 16 with similar pattern of reduction in NL with a 20 kg ha-1 starting from 220 to 160 and the lowest in control. Treatment interaction (ST x NL) were also found with significant effect on grain abd biomass yield of maize. The grain protein content was did not show any significant change with delay in sowing in season while the highest grain protein was observed with the application of 220 kg N ha-1. Radiation use efficiency (RUE g m-2) and crop growth rate (CGR g m-2 d-1) were significantly (P<0.05) decrease when the sowing delay with a 10 days interval starting from June 6 to July 16 and with NL reduction at the rate of 20 kg N ha-1 in each levels. It is concluded from the study that with proper management of sowing times and nitrogen levels the maize yield can be increase, minimize the production cost and N losses be reduced.
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