[1] Effect of water stress at different development stages on vegetative and reproductive growth of corn

A field study was carried out from 1995 to 1997 in order to determine the effect of irrigation and water stress imposed at different development stages on vegetative growth, grain yield and other yield components of corn (Zea mays L.). The field trials were conducted on a silty loam Entisol soil, with Pioneer 3377 corn hybrid. A randomised complete block design with three replications was used. Four known growth stages of the plant were considered and a total of 16 (including rain fed) irrigation treatments were applied. The effect of irrigation or water stress at any stage of development on plant height, leaf area index, grain yield per hectare, as well number of ears per plant, grain yield per cob and 1000 kernels weight, were evaluated. Results of this 3-year study show that all vegetative and yield parameters were significantly affected by water shortage in the soil profile due to omitted irrigation during the sensitive tasselling and cob formation stages.

[2] Noncompetitive Effects of Giant Foxtail on the Growth of Corn

Weed infestations severely reduce the yield grown corn with such yield reductions generally being attributed to competition. Noncompetitive (allelopathic) mechanisms have to date, however, received little consideration in agronomic situations. In the greenhouse, interference (competition + allelopathy) of the growth of corn (Zea mays L. Wf9 ✕ M14) by giant foxtail (Setaria faberii Herrm.) was determined in mixed culture treatments. When corn was seeded into pots with 6‐week‐old giant foxtail, corn height, fresh weight, and dry weight were reduced by as much as 90% when compared to comparable plants grown in monoculture. Competitive and allelopathic mechanisms were separated through the use of a stairstep apparatus, in which a nutrient solution passed through the rhizosphere of giant foxtail, into the rhizosphere of corn and was subsequently recycled through the system. The stairstep apparatus was used to determine the allelopathic interactions between corn and giant foxtail seedlings, mature giant foxtail, whole dead giant foxtail plants, and mascerated dead giant foxtail leaf and root material. Mature giant foxtail inhibited the growth of corn approximately 35% through an allelopathic mechanism. Elimination of competition through the use of stairsteps apparatus implicates a possible allelopathic mechanism in the interference of corn by giant foxtail that involves the exudation and leaching of phytotoxins from the roots of giant foxtail. Phytotoxins leached from dead giant foxtail reduced corn growth by as much as 50%. The relationships of allelopathy to competition, crop rotation, herbicidal activity, and physiological processes are discussed.

[3] Growth of corn in saline waters

Eight cultivars of Zea mays plus the wild species Zea diploperennis were screened for seedling saline tolerance up to 3.2% NaCl. The best performances were given by the cultivars Mo 17 and commercial Hawaiian Super Sweet Hybrid. These two were then field grown on coral‐cinder beds using drip irrigation with fresh of half‐strength sea water (1.5–1.7% dissolved solids). Growth and chemical data for Mo 17 at 12 weeks show reduced growth but the same percentage dry matter. Ash, protein and total sulfur were higher in saline plants, silica and total phosphorus lower. Na, K. Mg, and Cl were elevated and Ca reduced slightly. Fe was also increased in saline plants. Both Mo 17 and Super Sweet Hybrid corn flowered and produced seed which retained essentially normal viability both in fresh and salt water.

[4] A Study on Effects of Planting Dates on Growth and Yield of 18 Corn Hybrids (Zea mays L.)

In this study 18 new corn varieties consist of 15 foreign early and mid-mature single cross hybrids and 3 Iranian commercial hybrids (KSC704, KSC647and DC370) were evaluated at two sowing date (5 and 20 June) based on RCBD with 3 replications at Khorasan Razavi Agricultural Research Centre, Mashhad, Iran on 2009. This study showed that among all hybrids, EXP1 (16.03 ton/ha) and OSSK617 (15.51 ton/ha) had the highest yields in early planting (5 June) and EXP1 (16.52 ton/ha) and KDC370 (16.22 ton/ha) produced the highest, yields in late planting (20 June). Results of this experiment also indicated that yield component such as 300 kernel weight, kernel no. per row, kernel depth and ear length were adversely affected in delay planting condition. Delay planting reduced 300- kernel weight, kernel no. per row, kernel depth and ear length. Results of cluster analysis using Wards’ method divided the corn hybrids into 4 different clusters (low intra-group and high extra-group similarities). From the results of cluster analysis it is recommended to make crosses among genotypes in Clus1 (ZP434, BC582 and EXP2 hybrids) and Clus4 (ZP684, SIMON and KSC647) in breeding programmes. Classifying genotypes according to their agronomic traits with sophisticated multivariate techniques could reduce the time period and expenditure for crop improvement.

[5] Influence of Integrated Nutrient Management on Growth and Yield of Sweet Corn (Zea mays L. saccharata) under Temperate Conditions of Kashmir Valley

The growth and yield response of sweet maize (Zea mays (L.) saccharata) to varying levels of organic and inorganic fertilizers during the growing seasons of kharif 2010 and 2011 was studied under temperate conditions of Kashmir Valley. Twelve treatments comprising of sole and combination of organic and inorganic fertilizers were laid in a randomized block design with three replications. The results revealed that application of T10 [75% (NPK) + FYM (4.5 t/ha) + Biofertilizer (Azotobacter + Phosphate solubilizing bacteria (PSB))] significantly increased the number of days taken to tasseling, silking and milky stages and various other growth characters viz., plant height, leaf area index and dry matter accumulation at 15 days interval from sowing upto harvest and crop growth rate and relative growth rate at 7 days interval from 15 DAS upto harvest whereas, the lowest values of these parameters were recorded in unfertilized control. The treatment T10[75 % (NPK) + FYM (4.5 t/ha) + Biofertilizer (Azotobacter + Phosphate solubilizing bacteria (PSB))] proved to be significantly superior to rest of the treatments including unfertilized control in increasing cob yield with and without husk, fodder yield and green biomass yield during both years of experimentation, however, ratio of cob to fodder yield during 2011 and 2012 were recorded highest in treatment T3 [FYM (18 t ha-1)] and T2 [Recommended NPK kg ha-1 (90:60:40)], respectively, whereas unfertilized control recorded the lowest ratio of cob to fodder yield.

Reference

[1] Cakir, R., 2004. Effect of water stress at different development stages on vegetative and reproductive growth of corn. Field Crops Research, 89(1), pp.1-16.

[2] Bell, D.T. and Koeppe, D.E., 1972. Noncompetitive Effects of Giant Foxtail on the Growth of Corn 1. Agronomy Journal, 64(3), pp.321-325.

[3] Siegel, S.M., Siegel, B.Z., Massey, J., Lahne, P. and Chen, J., 1980. Growth of corn in saline waters. Physiologia plantarum, 50(1), pp.71-73.

[4] Beiragi, M.A., Khorasani, S.K., Shojaei, S.H., Dadresan, M., Mostafavi, K. and Golbashy, M., 2011. A study on effects of planting dates on growth and yield of 18 corn hybrids (Zea mays L.). Journal of Experimental Agriculture International, pp.110-120.

[5] Rasool, S., Kanth, R.H., Hamid, S., Raja, W., Alie, B.A. and Dar, Z.A., 2015. Influence of Integrated nutrient management on growth and yield of sweet corn (Zea mays L. Saccharata) under temperate conditions of Kashmir valley. Journal of Experimental Agriculture International, pp.315-325.