29 

 PUBLICATIONS DURING THE YEARS 1921-22. 



SCIENTIFIC PAPERS. 



CROPS AND PLANT GROWTH. 



I. Winifred E. Brenchley. ''Effect of Weight of Seed upon 



the Resulting Crop." Annals of Applied Biology, 1923. 

 Vol. X. pp. 223-240. 



Experiments were carried out in water cultures with peas and 

 barley, in which the competitive factors were eliminated as far as 

 possible in order that the results could be more closely correlated 

 with the initial weights of the seeds. 



The chief results are as follows : — 



1. — There is a steady and considerable rise in the dry weight of 

 the plants as the initial weight of the seed increases. This occurs 

 with both a limited and an abundant food supply. 



2. — The efficiency index (rate per cent, increase per day) falls 

 gradually as the weight of the seed rises. With prolonged periods 

 of growth this tends ultimately to counter-balance the initial 

 advantage gained by plants from the heavier seeds, but with 

 annual crops as cereals, roots, peas, etc., harvesting occurs before 

 this equilibrium is reached, leaving the advantage with the heavier 

 seeds. 



3. — The relative development of shoot and root is to some 

 extent influenced by the initial weight of the seed, but may vary 

 with the species and with the amount of available food. 



4. — The results lend support to the growing agricultural 

 practice of advocating the use of large heavy seed, especially with 

 annual crops. The advantage in the case of perennials would 

 appear to be less, if any, but this has not been determined by 

 laboratory experiments. 



II. Winifred E. Brenchley, assisted by Kharak Singh. 



"Effect of HigJi Root Temperature and Excessive 

 Insolation upon Growth." Annals of Applied Biology, 

 1922. Vol. IX. pp. 197-209. 



When similar water culture experiments are repeated at 

 different seasons of the year and under different environmental 

 conditions, certain variations in result occur which appear to be 

 associated with the temperature of the nutrient solution in which 

 the roots are immersed. Under ordinary environmental conditions 

 of temperature and sunlight the growth of peas, as of barley, is 

 seriously hindered by overcrowding, even when each plant receives 

 a similar supply of food and water. Not only is less dry weight 

 produced, but the pods become thin and distorted, and fail to 

 develop their seeds properly. 



Growth tends to be depressed in hot sunny weather when no 

 protection is afforded. The chief detrimental factors concerned 

 appear to be high temperatures at the roots, acting together with 

 strong and prolonged sunshine, though the two factors acting in- 

 dividually are much less harmful. Under these conditions, 

 crowding shelters the roots from overheating and the leaves from 

 too much sunlight, and up to a certain point crowded plants make 

 better growth than those spaced well apart. Overcrowding, 



