Governorate during 2009 & 2010 summer seasons to determine the critical period of weed competition between weeds and soybean crop through use of regression and economic approaches and also determine the relationship between weeds and soybean yield under three plant densities (105, 140 and 175 thousand plant/ fad.) and ten treatments in two types of treatments (in the first type soybean was hand weeded for different periods 3, 6, 9 and 12 weeks after sowing (W.A.S.) and for whole season ,then no further weeding was done while, in the second type weeds were allowed to grow for different periods at 3, 6, 9 (W.A.S.) until harvest the weeds were removed by hand-weeded and weed competition treatment for whole season on seed yield of soybean and associated weeds. The main results showed that, maximum yield losses of soybean due to weed competition in the whole season were 37.6 and 34.4 % from weed free treatments in 2009 and 2010 seasons. Mathematical model for the relationship between weed free and weed competition periods according to the recommended losing yield value (10), clear that critical period of weed competition under 105 thousand plants density/fad., were (6.5 and 7.0) weeks for weed free as well as (4.25 and 4.25) for weed competition in 2009 and 2010 seasons, respectively. Under 140 thousand plant density the respective values were (6.2 and 6.3) weeks for weed free as well as (3.9 and 4.2) for weed competition and for 175 thousand plant density were (5.9 and 5.6) weeks for weed free as well as (3.5 and4.15) weeks for weed competition in 2009 and 2010 seasons, respectively. The critical period of weed treatments over plant densities were (6.45 and 6.4) weeks for weed free as well as (4.9 and 4.65) weeks for weed competition in 2009 and 2010 seasons, respectively. All weed competition exerted significant efficiency in controlling annual weeds. Weed free for the whole season treatment gave the best control for annual weeds gave the highest values of yield and yield components in two seasons. The sowing 175000 plant/fad. gave the lowest weight for dry weight for annual weeds and the tallest plants in first and second seasons. 105000 plant/fad., gave the best values of No. of branches and seed weight/plant in the first and second seasons. 140000 plant/fad., gave the highest value of No. of seed pod, weight of 100 seed and yield ton/fad. in the two seasons. Plots weeded at 3 and 6 week after sowing showed the best performance in all aspects of soybean. Such knowledge should be disseminated to farmers to keep soybean yield losses of weed competition to maintain maximum soybean seed yield. This study showed that negative correlation for annual weed weight and all studied characters under study.

Two field experiments were conducted at Moshtohor region, Kalubia Governorate, Egypt, during 2019/20 and 2020/21 seasons, to study the effect of three sowing dates (1 st November, 15 th November, 1 st December) and three harvesting dates (Harvesting at 150 DAS after sowing , Harvesting at 165 DAS after sowing, Harvesting at 180 DAS after sowing) on yield and yield components of two barley cultivars (Giza 2000 and Bhoth 244). The experimental design was randomized complete block design using split split-plots arrangement with three replications. Sowing dates was arranged in the main plots and barley cultivars was arranged at random in the sub plots, while harvesting dates were arranged randomly by in the sub sub-plots. The main results were as follows: Sowing at 1 st or 15 th of November gave the highest values of all studied traits except spike length and harvest index in first season and plant height in second season. Meanwhile, Bhoth 244 cultivar gave the highest values of spike length, No. spikelets spike -1 , spike weight, No. grains spike -1 , grain yield fed -1 and straw yield fed -1 , whereas Giza 2000 cultivar gave the highest values of plant height, 1000-kernel weight and harvest index in the first and second seasons. Harvesting at 150 DAS increased significantly spike weight, No. grains spike -1 , 1000kernel weight and straw yield fed -1 compared with the other harvesting dates, while spike length, No. spikelets spike -1 , grain yield fed -1 and harvest index increased significantly by harvesting at 180 DAS in both seasons. Plant height, spike weight, No. grains spike -1 , grain yield fed -1 and straw yield fed -1 were affected by the interaction between sowing dates and barley cultivars in both seasons except plant height in the second season and No. grains spike -1 in the first season. Moreover, plant height, spike length, spike weight, No. grains spike -1 , 1000-kernel weight, grain yield fed -1 , straw yield fed -1 and harvest index were affected by the interaction between sowing dates and harvesting dates in both seasons except plant height, spike length, straw yield fed -1 and harvest index in the first season. While, plant height, No. spikelets spike -1 , spike weight, No. grains spike -1 , 1000-kernel weight, grain yield fed -1 , straw yield fed -1 and harvest index were affected by the interaction between barley cultivars and harvesting dates in both seasons except plant height, No. spikelets spike -1 , grain yield fed -1 , straw yield fed -1 and harvest index in the first season. Regarding the interaction effect, among sowing dates, barley cultivars and harvesting dates were significant differences of plant height, spike weight, No. grains spike -1 , 1000-kernel weight, grain yield fed -1 , straw yield fed -1 and harvest index in both seasons except straw yield fed -1 and harvest index in the first season. It can be concluded that sowing Bhoth 244 cultivar in 1 st or 15 th November and harvesting at 180 DAS produced the height yield productivity under the conditions of this experiment.

Five rice lines and three testers were crossed in line x tester mating design and the resultant fifteen hybrids along with their eight parents were evaluated under normal and drought conditions (irrigation every 12 days). This investigation was undertaken at the experimental farm of Rice Research and Training Center (RRTC), Sakha Agricultural Research Station, Kafr El-Sheikh, Egypt during 2019 and 2020 growing season. Genetic diversity, combining ability, heterosis, and antioxidant enzymes were studied. Four primers were used to study genetic diversity. The results revealed a total number of 7 alleles were ranged from one to three alleles per locus, the average of major allele frequency, gene diversity, and (PIC) were 0.607, 0.45, 0.46), respectively. The GD dendrogram revealed the close similarity among the genotypes; IET 1444, GZ1368 and G177 clustered together in the main cluster. On another hand, NP856-9 diverged in sub cluster and the other genotypes G178, G179, A22, and G182 were clustered together. The drought had an intensive inhibition on studied traits, plant height, chlorophyll content, grain yield plant-1 and 1000 grain weight. Otherwise, all genotypes were more earliness under drought than under normal. Highly significant differences were detected among genotypes and their partitions for all studied traits. Both additive and non-additive are important in the inheritance of studied traits. The parents GZ 1368 under normal irrigation and combined data and IET 1444 under stress condition seemed to be the best combiner for grain yield plant-1. The cross NP856-9 X GZ 182 revealed the highest significant and positive SCA effects for chlorophyll content and grain yield/plant. The most desirable midparent and better-parent heterosis for grain yield plant-1 were detected for the crosses IET1444 x G182 and NP856-9 x G182, respectively in the combined data. Results indicated that the activity of antioxidant enzymes: CAT, APX, SOD, and MDA enhanced under drought conditions. Similarly, proline accumulation increased due to water stress.

Two field experiments were conducted at the Experiment and Research Center, Fac. Agric., Moshtohor, Benha Univ., during 2014/15 and 2015/16 seasons. The aim of this study was response to investigate the effect of three wheat varieties (Misr 2, Sakha 94 ,and Sids 12)to four planting methods (prodcasting, rows, hills on ridges and rows on beds ) and two application methods (prodcasting and drilling). The results indicated that:Misr 2 variety gave the highest values of plant height, spike length, No. tillers and spikes m -2 , No. spikelets spike -1 , weight of grains spike -1 , biological and grain yields fed -1 compared with the other varieties in the first and second seasons. planting by rows on bed method increased significantly plant height, spike length, No. otillers and spikes m -2 , No. spikelets spike -1 , weight of grains spike -1 , 1000-grain weight, biological and grain yields fed -1 compared with the other planting methods in the first and second seasons.Plant height, spike length, No. tillers and spikes m -2 , No. spikelets spike -1 , weight of grains spike -1 , 1000grain weight, biological and grain yields fed -1 increased significantly by prodcasting N application method in the first and second seasons.Plant height, No. tillers and spikes m -2 , No. spikelets spike -1 , weight of grains spike -1 , 1000-grain weight, biological and grain yields fed -1 were affected by the interaction between wheat varieties and planting methods in the first and second seasons except 1000-grain weight in the second season.Plant height, No. tillers and spikes m -2 , No. spikelets spike -1 , 1000-grain weight and biological yield fed -1 were affected by the interaction between varieties and nitrogen application methods in the first and second seasons except plant height and No. spikelets spike -1 in the first season. Plant height, No. tillers and spikes m -2 , No. spikelets spike -1 , biological and grain yields fed -1 were affected by the interaction between planting methods and nitrogen application methods in the first and second seasons except plant height, No. tillers m -2 , No. spikelets spike -1 and grain yield fed -1 in the first season. Also, plant height, No. tillers and spikes m -2 , weight of grains spike -1 , 1000-grain weight, biological and grain yields fed -1 responded significant to the interaction of the three involved factors (varieties x planting methods x N application methods).It could be concluded that under the conditions of the experiment, planting Misr 2 var by rows on bed method under proadcasting N application is recommended.

Two field experiments were conducted at the Experiment and Research Center, Fac. Agric., Moshtohor, Benha Univ., during 2018 and 2019 summer seasons. The aim of this was to study response of three yellow maize hybrids (SC 2055, SC 176 and SC P3737) to three N fertilizer rates (06, 06 and 120 kg N fed-1) and two Nano-N foliar applications (Without and Nano foliar applications). The experimental design was randomized complete block design (RCBD) using split split-plots arrangement with three replications. The yellow maize hybrids, N fertilizer levels and Nano-N foliar applications were arranged at random in the main plots, sub-plots and sub sub-plots, respectively. Single Cross P3737 was significantly earlier than the other hybrids regarding 50% tasseling and silking. Also, SC P3737 was superior to the other two hybrids in most of the studied traits. The highest values of plant height, ear length, ear diameter, No. grains row-1 , ear weight, ear grains weight, 100-grain weight, Forge yield fed-1 and grain yield fed-1 were obtained with fertilizer level of 120 N fed-1. On the other hand, the earliest tasseling and silking were recorded with 06kg N fed-1. Nano foliar application gave the greatest of all grain yield and attributes of yellow maize hybrids as compared with untreated. It could be concluded that under the conditions of the experiment, planting SC P3737 under 90 or 120 N fed-1 and nano foliar application is recommended.