GENOTYPE AND PLANTING DATE EFFECTS ON PHENOLOGY, GROWTH AND YIELD OF WHITE MAIZE

Abstract

Three experiments were conducted at the Sher-e-Bangla Agricultural University in Rabi and Kharif-I seasons of 2016-2017, 2017-2018 and 2017to study the effects of planting date on the phenology, growth and yield of four genotypes of white maize viz., PSC 121, Yangnuo-30, Changnau-6 and Youngnau-7. The planting dates were, November 25, December 10 and December 25 in Rabi and May 29, June 21 and July 7 in Kharif-I. A delay in planting delayed the time required for seedling emergence and to reach the 6-leaf collar, tasseling, silking and maturity stages, and reduced yield of the maize genotypes in both seasons. The recorded maximum time for seedling emergence after planting was 9.67 d for Yungnuo-30 in Kharif-I, 2017 and 5 d for PSC-121 in Rabi 2017 season when the planting time was delayed by 30d. The genotype PSC-121 took 43.67 d to reach the 6-leaf collar stage in Rabi 2017 season when plantingwas done on December 26, i.e., delayed by 30 d from November 25 where as Yangnuo-7 took only 30 d with the optimum planting date of November 25. In respect of the time to reach the tasseling stage, PSC-121 needed 69.33 d in Rabi 2016 when planting was delayed, but Yangnuo-7 needed a shorter time to reach the tasseling stages. With delayed planting, PSC-121 needed a long period of 81.33 d to reach the silking stage. Likewise, delayed planting substantially delayed maturity. The genotype PSC-121 took the maximum time, 141.33 d, to mature in the Rabi season due to delayed planting, where as the time needed for maturity was minimum, 111 d (Yangnuo-7) when planting was done at the optimum time, i.e., November 25. The genotype PSC-121, when planted at the optimum time, had the highest leaf area, greater than 0.80 m 2 plant -1 in the first Rabi season. However, the genotypeplanting

date interaction effect on LAI was not consistent. The crop growth rate (CGR) was the highest, 23.32, between 90 days after planting (DAS) and maturity, for November 25 sown PSC121. The same combination (PSC-121 x November 25 planting) showed the highest relative growth rate (RGR) of 0.06 and the highest net assimilation rate (NAR) of 0.003 at 45-60 DAS. The November 25-planting-PSC-121 combination was also found to be superior in terms of stover production (113 and 124 g plant in Rabi and kharif, respectively) and ear weight (156, 108 and 154 g plant vii -1 , respectively, in first Rabi, kharif and second Rabi). Planting at the optimum time in Rabi (November 25) gave the highest dry matter plant -1 (207-278g plant -1 ) in PSC-121. The November 25 planting x PSC-121 combination gave the best results in terms of the yield contributing characters, 100 seed weight (32g), grain number plant -1 (249-322) and grain weight plant (95-160g). Consequently, the highest seed yield was obtained with November 25 sown PSC-121 (9.982-10.770 t ha -1 ). Planting date was of critical importance in maize yield. For example, the highest yield of 11.46 t ha -1 (PSC-121) in the Rabi season was achieved when planting was done on November 25, and in general, the earlier the planting the higher was the yield irrespective of genotype. The total growing degree days (GDD) was less in PSC-121 (1747.05 and 1727.50) than that in Yangnuo-7 (1915.20 and 1905.60) with the first date of planting. There was a negative correlation between temperature and yield. On an average, the seed yield in the Rabi season was 9.852 tha , while in the Kharif season it was 6.070 tha -1 . Thus, there was a 38% lower yield in the warm Kharif season than that in the cool Rabi season. Overall, planting PSC-121 early on in the Rabi season would be the appropriate practice in the cultivation of white maize in Bangladesh. However, these results need to be fine-tuned through further experimentation in different maize growing areas of the country.