Application of phosphorus and properly timed irrigation appreciably increased yields of late planted wheat. However, phosphorus applications reduced the bushel weights. Higher protein content was obtained by increasing nitrogen rates and by timely irrigation.

Recently the list of agricultural chemicals has been extended to include a group of compounds known collectively as 'Growth Retardants'. CCC is one of them; the name CCC is an abbreviated form of the chemical name Chlorocholine Chloride or (2-Chloroethyl) trimethylammonium Chloride. It is also known by the generic name Chlormequat and the trade name Cycocel. Like most growth retardants CCC has the characteristic effect of inhibiting stem elongation with relatively smaller effects on other parts of susceptible plants (de Vos et. Al., 1967). Most growth retardants have been used commercially simply on ornamental plants. It is only recently with the discovery of CCC (Tolbert, 1960 a) that a much larger field of application has been opened up. Early in the 1960s CCC was found to prevent grain losses in wheat caused by stem lodging during violent weather conditions or when stems were weakened by fungal infections such as eyespot (Cercosporella herpotrichoides). More recently CCC has been shown to increase grain yields even in absence of lodging. Here however, the results have been very variable and in one instance yield reductions of up to 13 percent were recorded (Geering, 1965). The aims of the current study were to investigate the effects of CCC on wheat yields under non-lodging conditions. Hence the short-strawed wheat cv. Gamenya was chosen. The extent to which wheat plants respond to treatment with CCC depends on varietal, soil and climatic factors as well as dosage level, type of application and timing of application. Although the effects of these factors on the action of CCC have been studied extensively in Europe and Israel very little work has been done in New Zealand. It was therefore thought that an investigation of the effects of CCC in relation to various agronomic factors was worthwhile.

Spring wheat (Triticum aestivum L.) was grown for 2 years with three shelter conditions: (a) exposed, (b) surrounded by a slat barrier, and (c) adjacent to tree shelterbelts. Leaf water potential, stomatal diffusion resistance, and meteorological factors were monitored on selected days. The shelterbelt and slat-barrier plots received 28 and 69% as much wind as the exposed plot, respectively. Air temperature was slightly higher in the sheltered plots. Vapor pressure deficits were similar for all three conditions. Generally, leaf water potential was consistently lower in the exposed compared to the sheltered plots. The more favorable leaf water potentials were associated with those plots receiving less total wind movement. Stomatal diffusion resistance was less and at a lower leaf water potential for exposed compared to sheltered plants. The data indicate that water relations of wheat plants are more favorable for plant growth and yield when grown with shelter compared to exposed conditions.

4 tables

Cebada-Hordeum vulgare | Trigo-Triticum aestivu | Maestría en Ciencias | Maestría

87 p. | Trigo | 12134 | Tesis (Mag Sc)) | Cebada